Fluid-structure coupling analysis method and device for slender objects based on finite particle method and SPH

Abstract

The present application discloses a method and device for fluid-solid coupling analysis of slender beams based on the finite particle method and SPH. The structure is discretized into beam particles, the slender beam is simulated by a two-dimensional beam unit, the fluid is simulated by an SPH particle, the pressure transmission of the coupling interface is simulated by a transmission unit, and the displacement coordination of the coupling interface is simulated by a coupling unit. The finite particle method is used for dynamic analysis, and the pure deformation and rigid body displacement of the two-dimensional beam unit are separated by virtual reverse motion, and then the internal force increment of the plane beam unit is calculated; the SPH calculation fluid model is used to give the discrete format of the fluid control equation, the tensile stability control method based on the Shepard Filter and particle displacement correction technology, and the frog leap time integration scheme; the FPM-SPH interface coupling scheme is proposed, the coupling interface particle arrangement method is given, the physical quantity correspondence between the beam particles and the fluid particles at the interface is established, and a two-dimensional beam fluid-solid coupling analysis framework is built. The present application is simple and efficient in calculation, and improves the deficiencies of existing research.

Description

Technical Field

[0001] The present application relates to a fluid-structure coupling analysis technology for slender objects, and in particular to a fluid-structure coupling analysis method and device for slender objects based on the finite particle method and SPH. Background Art

[0002] In the field of structural engineering, there are many scenarios involving the interaction between fluids and structures, which has also been one of the research hotspots in recent years. For example, the structural response in dam break scenarios, the dynamic response of large floating structures under complex wave loads, etc. The interaction between fluids and structures is also called fluid-solid coupling, that is, the fluid pressure acts on the structure to cause large deformation and displacement, and at the same time, the structural displacement will also affect the fluid boundary, involving difficulties such as the free surface of the fluid and the strong nonlinear response of the structure. In marine structures, fluid-solid coupling problems are often modeled using numerical simulation methods in order to simulate and interfere with them. The numerical simulation method has a wide range of application scenarios in simulation calculation fields such as industrial software and structural numerical calculation software.

[0003] Fluid-structure interaction has numerous applications in computation. For example, existing structural calculation methods employ a large number of planar solid elements for fluid-structure interaction simulation, resulting in low computational efficiency. Existing fluid calculation methods often employ mesh-based methods such as finite element and finite volume methods. When the coupling interface involves severe deformation, mesh-based methods require more complex operations and techniques to capture the interface. Furthermore, due to the presence of convection terms, numerical diffusion is difficult to avoid, and the free surface of the liquid is unclear. Therefore, a fluid-structure interaction analysis method for slender beams based on SPH and the finite particle method is a computational analysis method that needs further development and improvement in current engineering applications. This method can effectively reduce the number of elements, improve computational efficiency, and provide a good foundation for further expanding the application of slender components in offshore structures.

[0004] Current analysis methods for fluid-structure interaction problems of slender beams often have the following defects:

[0005] 1) For complex fluid-structure coupling behaviors, it is often difficult to carry out model tests due to factors such as high test costs, long cycles, and constraints on test conditions.

[0006] 2) For structural simulation, strong fluid action often causes large deformation of the structure. The use of traditional structural numerical analysis methods (such as the finite element method, etc.) often faces problems such as grid distortion, singularity of the overall stiffness matrix, and low efficiency in solving large nonlinear equations. It is difficult to solve large structural deformations and it is difficult to meet the needs of actual engineering structure design calculations.

[0007] 3) For fluid simulation, the evolution of the free surface is very dramatic, and there are strong nonlinear free surface flow problems such as rolling deformation, breakup and fusion of the free surface. Numerical analysis methods based on Euler description (such as the finite volume method, etc.) are difficult to avoid numerical diffusion due to the existence of convection terms, and the free surface of the liquid is not clear.

[0008] 4) Existing slender beam modeling methods use planar solid elements to simulate panels. However, this approach results in a large number of model elements, resulting in complex and computationally intensive calculations, making it difficult to effectively address large-scale slender beam structural engineering problems.

[0009] 5) Existing fluid-structure coupling analysis methods often focus on grid-grid / grid-particle fluid-structure coupling calculations, but there is little research on particle-particle coupling calculations and analysis. There is a lack of effective calculation methods for the exchange of physical quantity information such as force and displacement between particles at the coupling interface.

[0010] The existing modeling and analysis methods for fluid-structure coupling problems of slender beams have problems such as a lack of modeling and analysis methods, high cost of fluid-structure coupling tests, defects in handling large structural deformation problems, difficulty in tracking the free surface motion of the fluid, and large and complex numerical simulation calculations. Summary of the Invention

[0011] The present application provides a fluid-structure coupling analysis method and device for slender objects based on the finite particle method and the smoothed particle hydrodynamics method (SPH) to at least solve the above technical problems existing in the prior art.

[0012] According to a first aspect of the present application, a fluid-structure coupling analysis method for a slender object based on a finite particle method and SPH is provided. The method creates a slender object structural model with finite particles and a fluid model based on the smoothed particle method (SPH). Based on the slender object structural model and the fluid model, and in combination with the interface coupling between the slender object and the liquid, the slender object structure is discretized and represented by particles. The method comprises:

[0013] The slender object is simulated by two-dimensional slender object units, and the fluid is simulated by the SPH fluid model. The pressure transmission at the coupling interface between the slender object and the liquid is simulated by the transmission unit, and the displacement coordination of the coupling interface is simulated by the coupling unit. The force analysis is performed on the discrete particles of the slender object to obtain the virtual inverse motion separation structural deformation and rigid body displacement of the slender object, and the deformation and internal force of the slender object in the two-dimensional direction are obtained.

[0014] Determine the particle approximate fluid governing equations for slender objects based on transfer elements and SPH fluid models, and discretize the fluid continuity equation and momentum equation;

[0015] The approximate fluid control equation is subjected to tensile stability control based on the Shepard filter algorithm and particle correction technology; the discrete fluid continuity equation is solved by leapfrog time integration to obtain the particle physical quantities of the SPH particle at the next moment; the momentum equation is solved by central difference method to obtain the particle motion equation of the finite particle method (FPM) of the slender object;

[0016] A coupling interface particle arrangement method is used to evenly distribute multiple layers of virtual particles at the coupling interface. The simulated physical quantities of the virtual particles at the coupling interface, as well as the corresponding relationship between the physical quantities, are determined based on the transfer unit and the coupling unit. The pressure distribution and transmission at the coupling interface are obtained by analyzing the transfer unit, and the displacement of the virtual particles is obtained by analyzing the coupling unit, thereby establishing a two-dimensional fluid-structure coupling analysis framework for slender objects.

[0017] Based on the analysis framework, the fluid-structure coupling of the slender object is analyzed to obtain corresponding analysis results.

[0018] In some executable embodiments, obtaining the virtual inverse kinematics of the slender object by separating the structural deformation and the rigid body displacement to obtain the deformation of the slender object in two dimensions and the internal force applied thereto includes:

[0019] By means of virtual inverse motion of the slender object, the rigid body translation and rotation of the inverse motion of the slender object are calculated;

[0020] Deduct the rigid body translation and rotation of the mass point to determine the unit deformation information of the slender object;

[0021] The unit axial force is determined by unit deformation, and the internal forces of the mass points at both ends of the slender object unit are determined based on the force balance relationship.

[0022] In some executable embodiments, simulating fluid using the smoothed particle method (SPH) includes:

[0023] Based on the interpolation principle and kernel estimation method, the partial differential equation of the SPH fluid model is converted into an integral equation. The physical quantities of discrete particles are determined based on the integral equation. The fluid calculation domain is discretized into a series of particles carrying physical information by adding the physical quantities. The physical quantity of each particle is obtained by weighting the physical quantities of other particles in a certain area around the particle.

[0024] And the attribute information of the particle at the previous moment is iteratively obtained to obtain the attribute information of the particle at the next moment.

[0025] In some executable embodiments, the method of uniformly distributing multiple layers of virtual particles on the coupling interface using the coupling interface particle arrangement method includes:

[0026] At the coupling interface, along the axis of the slender object, multiple layers of virtual particles with a distribution density similar to that of the fluid particles are arranged with the same particle spacing.

[0027] In some executable embodiments, simulating the pressure transmission at the coupling interface between the elongated object and the liquid by a transmission unit includes:

[0028] Determine the effect on virtual particle B i The interface pressure on the virtual particle B i The interface pressure on the plane is decomposed into the mass points of the slender object unit. Specifically, it is assumed that the relative position relationship between the plane slender object unit and the corresponding virtual particle always remains unchanged. The virtual particle B i The projection position of the slender object element A0A1 on the coupling boundary is B ip , then the coupling force transmitted to the mass points at both ends of the slender object unit is in The virtual particle coupling force Along the local coordinate system of the slender object The direction component, d is the distance from the virtual particle projection point to the virtual particle, is the equivalent coupling force acting on the particle at the end of the slender object, N is the shape function matrix, N1=1-3ξ 2 +2ξ 3 , N2=(ξ-2ξ 2 +ξ 3 )l,N3=3ξ 2 -2ξ 3 ,N4=(-ξ 2 +ξ 3 )l,N′ k N k The derivative of (k=1,2,3,4) with respect to ξ, l is the length of the slender object unit A0A1, A0 to B ip The length of the slender object unit is shown in Figure 2, and A0 and A1 are the two end points of the slender object unit respectively.

[0029] In some executable embodiments, the method further includes: updating the position of the virtual particle at the coupling interface according to the displacement of the coupling unit, that is, the displacement of the slender object particle. Specifically, assuming that the distance between the virtual particle at the coupling interface and the slender object unit remains unchanged during the movement, the angle of the slender object unit rotating counterclockwise at time t+1 relative to time t is θ, and the virtual particle B belonging to the slender object unit is i , the updated position at time t+1 for: d′=R(θ)·d, in, are the positions of the two end points of the slender object unit at time t+1, R(θ) is the rotation matrix, and d is the rotation matrix from B at time t. ip Point B i vector.

[0030] In some executable embodiments, obtaining the particle motion equation of the finite particle method (FPM) of the slender object includes:

[0031] Assuming that the particles are in a state of dynamic equilibrium in each time iteration step during the structural deformation process, the motion of any particle follows Newton's second law, which is: m α is the mass of particle α, and They represent the external force, internal force and damping force of the particle α respectively, μ is the damping coefficient, which is a set constant; through the central difference algorithm, the displacement of the particle in the path unit is directly obtained, and the position and deformation information of the structure at the next moment are obtained.

[0032] According to a second aspect of the present application, a fluid-structure coupling analysis device for a slender object based on a finite particle method and SPH is provided, comprising:

[0033] Create units for creating finite mass slender object structure models and SPH-based fluid models;

[0034] a characterization unit configured to discretize the structure of the slender object into mass points for characterization based on the slender object structure model and the fluid model and in combination with an interface coupling mode between the slender object and the liquid;

[0035] Simulation unit, used to simulate the slender object through the two-dimensional slender object unit, simulate the fluid through the SPH fluid model, simulate the pressure transmission of the coupling interface between the slender object and the liquid through the transmission unit, and simulate the displacement coordination of the coupling interface through the coupling unit;

[0036] A force analysis unit is used to perform force analysis on discrete mass points of the slender object, obtain the virtual reverse motion separation structure deformation and rigid body displacement of the slender object, and obtain the two-dimensional deformation and internal force of the slender object;

[0037] Determination unit, used to determine the particle approximate fluid governing equations of slender objects based on the transfer unit and SPH fluid model, and the discrete fluid continuity equation and momentum equation;

[0038] A processing unit is configured to perform stretching stability control on the approximate fluid control equation based on a Shepard Filter algorithm and a particle correction technique; solve the discrete fluid continuity equation by a leapfrog time integration method to obtain the particle physical quantities of the SPH particle at the next moment; solve the momentum equation by a central difference method to obtain the particle motion equation of the finite particle method (FPM) of the slender object;

[0039] A construction unit is used to uniformly distribute multiple layers of virtual particles at the coupling interface using a coupling interface particle arrangement method, and to determine the simulated physical quantities of the virtual particles at the coupling interface, as well as the corresponding relationship between the physical quantities, based on the transfer unit and the coupling unit. The pressure distribution transmission at the coupling interface is obtained by analyzing the transfer unit, and the displacement of the virtual particles is obtained by analyzing the coupling unit, thereby building a two-dimensional fluid-structure coupling analysis framework for slender objects.

[0040] The analysis unit is used to analyze the fluid-structure coupling of the slender object based on the analysis framework to obtain corresponding analysis results.

[0041] In some executable embodiments, the force analysis unit is further configured to:

[0042] By means of virtual inverse motion of the slender object, the rigid body translation and rotation of the inverse motion of the slender object are calculated;

[0043] Deduct the rigid body translation and rotation of the mass point to determine the unit deformation information of the slender object;

[0044] The unit axial force is determined by unit deformation, and the internal forces of the mass points at both ends of the slender object unit are determined based on the force balance relationship.

[0045] In some executable embodiments, the simulation unit is further configured to:

[0046] Based on the interpolation principle and kernel estimation method, the partial differential equation of the SPH fluid model is converted into an integral equation. The physical quantities of discrete particles are determined based on the integral equation. The fluid calculation domain is discretized into a series of particles carrying physical information by adding the physical quantities. The physical quantity of each particle is obtained by weighting the physical quantities of other particles in a certain area around the particle.

[0047] And the attribute information of the particle at the previous moment is iteratively obtained to obtain the attribute information of the particle at the next moment.

[0048] According to a third aspect of the present application, an electronic device is provided, including:

[0049] at least one processor; and

[0050] a memory communicatively connected to the at least one processor; wherein,

[0051] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the steps of the fluid-structure interaction analysis method for slender objects based on the finite particle method and SPH.

[0052] According to a fourth aspect of the present application, a non-temporary computer-readable storage medium is provided, which, when the instructions in the storage medium are executed by a processor of an electronic device, enables the electronic device to perform the steps of the fluid-solid coupling analysis method of slender objects based on the finite particle method and SPH.

[0053] The present application discloses a method and device for analyzing the fluid-solid coupling of slender objects based on the finite particle method and SPH, an electronic device, and a storage medium. The method calculates the fluid-solid coupling problem of slender beams through numerical methods. The simulation has low cost and short cycle time, and the simulation is good with the test results. The modeling and analysis of the slender beam structure of the present application is based on the finite particle method. The slender beam is simulated by two-dimensional beam elements. The overall stiffness matrix does not need to be integrated, which avoids the morbid problem of the overall stiffness matrix and can effectively analyze the dynamic response of the slender beam during movement. At the same time, virtual reverse motion is used to separate the rigid body displacement to obtain the pure deformation of the structure. The method can effectively analyze the dynamic response of the unit such as internal force and deformation under large deformation when the slender beam structure interacts with the fluid, providing an effective analysis method for the calculation of the structure. The fluid analysis of the present application is based on the SPH method and the Lagrangian description. It can simulate complex fluid flow and large deformation, track free surfaces and moving boundaries, improve numerical stability through tensile stability control, effectively analyze the nonlinear free surface flow of the fluid, and provide an effective analysis method for fluid simulation. This application proposes to simulate slender beams with two-dimensional beam elements, construct slender beam structures with two-dimensional beam elements, and obtain the unit pure deformation and particle internal force through the virtual reverse motion of the beam element, avoiding the deformation and internal force calculation of the planar solid element, and greatly reducing the complexity of the calculation. This application replaces the planar solid element with several two-dimensional beam elements. Based on the characteristics of the finite particle method that the particle motions are independent of each other and the solution of the unit internal force is independent of each other, the application takes advantage of the high parallelism of the finite particle method, and with the help of advanced parallel computing technologies such as Graphics Processing Unit (GPU) and Distributed Parallel Message Passing Interface (MPI), it can greatly improve the calculation speed of the slender beam structure and solve the large-scale and large-scale fluid-solid coupling problem of slender beams.

[0054] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The above and other objects, features and advantages of the exemplary embodiments of the present application will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present application are shown in an illustrative and non-limiting manner, in which:

[0056] In the drawings, the same or corresponding reference numerals denote the same or corresponding parts.

[0057] Figure 1 A flow chart of a fluid-structure coupling analysis method for a slender object based on the finite particle method and SPH according to an embodiment of the present application is shown;

[0058] Figure 2 A schematic diagram of virtual reverse motion of a plane beam unit according to an embodiment of the present application is shown;

[0059] Figure 3 A schematic diagram of searching for particles within a smooth radius according to an embodiment of the present application is shown;

[0060] Figure 4 A schematic diagram of particle distribution at the coupling interface of an embodiment of the present application is shown;

[0061] Figure 5 A schematic diagram of pressure transmission at the coupling interface according to an embodiment of the present application is shown;

[0062] Figure 6 A schematic diagram of coupling interface displacement coordination according to an embodiment of the present application is shown;

[0063] Figure 7 A schematic diagram of the structure of a fluid-structure coupling analysis device for slender objects based on the finite particle method and SPH according to an embodiment of the present application is shown;

[0064] Figure 8 A schematic diagram of the structure of an electronic device according to an embodiment of the present application is shown.

[0065] Explanation of numbers: 1: beam point, 2: beam element, 3: virtual particle, 4: fluid particle. DETAILED DESCRIPTION

[0066] In order to make the purpose, features, and advantages of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0067] Figure 1FIG. 1 shows a flow chart of a fluid-structure coupling analysis method for a slender object based on the finite particle method and SPH according to an embodiment of the present application. Figure 1 As shown, the fluid-structure coupling analysis method for slender objects based on the finite particle method and SPH in the embodiment of the present application includes the following processing steps:

[0068] Step 101: Create a finite particle structure model of a slender object and a smoothed particle method (SPH)-based fluid model. Based on the slender object structure model and the fluid model, and in combination with the interface coupling between the slender object and the liquid, the slender object structure is discretized and represented by particles.

[0069] In the embodiment of the present application, before executing the specific steps of the fluid-structure coupling determination method, it is necessary to create relevant simulation models in advance. Specifically, at least a slender object structure model and a fluid model are created to facilitate the characterization of the slender object's structure in a particle manner, and to mathematically model the fluid to simulate its fluid properties. In the embodiment of the present application, the slender object is mainly a rigid slender object. As an example, the slender object is a slender beam structure. The technical solution of the embodiment of the present application is applicable to scenarios such as structural response in dam break scenarios and the dynamic response of large floating structures under complex wave loads.

[0070] Step 102 , simulating the slender object using two-dimensional slender object units, simulating the fluid using an SPH fluid model, simulating the pressure transmission at the coupling interface between the slender object and the liquid using transmission units, and simulating the displacement coordination at the coupling interface using coupling units.

[0071] In the embodiment of the present application, the fluid is simulated by the smoothed particle hydrodynamics method (SPH), including:

[0072] Based on the interpolation principle and kernel estimation method, the partial differential equation of the SPH fluid model is converted into an integral equation. The physical quantities of discrete particles are determined based on the integral equation. The fluid calculation domain is discretized into a series of particles carrying physical information by adding the physical quantities. The physical quantity of each particle is obtained by weighting the physical quantities of other particles in a certain area around the particle. The attribute information of the particle at the previous moment is iteratively obtained from the attribute information of the particle at the next moment.

[0073] The pressure transmission through the coupled interface between the slender object and the liquid is simulated by the transfer element, including:

[0074] Determine the effect on virtual particle B i The interface pressure on the virtual particle B iThe interface pressure on the plane is decomposed into the mass points of the slender object unit. Specifically, it is assumed that the relative position relationship between the plane slender object unit and the corresponding virtual particle always remains unchanged. The virtual particle B i The projection position of the slender object element A0A1 on the coupling boundary is B ip , then the coupling force transmitted to the mass points at both ends of the slender object unit is in The virtual particle coupling force Along the local coordinate system of the slender object The direction component, d is the distance from the virtual particle projection point to the virtual particle, is the equivalent coupling force acting on the particle at the end of the slender object, N is the shape function matrix, N1=1-3ξ 2 +2ξ 3 , N2=(ξ-2ξ 2 +ξ 3 )l,N3=3ξ 2 -2ξ 3 ,N4=(-ξ 2 +ξ 3 )l,N′ k N k The derivative of (k=1,2,3,4) with respect to ξ, l is the length of the slender object unit A0A1, A0 to B ip The length of the slender object unit is shown in Figure 2, and A0 and A1 are the two end points of the slender object unit respectively.

[0075] Based on the aforementioned models, simulations of the respective objects are performed to determine the analysis objects of the fluid-structure coupling between the slender beam and the liquid, so as to analyze the dynamic response of the slender beam under complex wave loads.

[0076] Step 103 : Perform force analysis on the discrete mass points of the slender object to obtain the virtual inverse kinematic separation structure deformation and rigid body displacement of the slender object, and obtain the two-dimensional deformation and internal force of the slender object.

[0077] Specifically, through virtual inverse motion, the rigid body translation and rotation of the reverse motion are calculated; by deducting the rigid body translation and rotation of the particle, the pure deformation of the beam unit is determined; the unit axial force is determined by the unit deformation, and the internal force of the particles at both ends of the beam unit is obtained from the force balance relationship.

[0078] Step 104 : Determine the particle approximate fluid governing equations, the discrete fluid continuity equation, and the momentum equation of the slender object based on the transfer unit and the SPH fluid model.

[0079] In the embodiment of the present application, the particle approximation fluid control equation, the discrete fluid continuity equation and the momentum equation can be determined by the existing fluid-related equations and momentum equations, and the details are not repeated here.

[0080] Step 105: Perform stretching stability control on the approximate fluid control equation based on the Shepard Filter algorithm and particle correction technology; solve the discrete fluid continuity equation by leapfrog time integration to obtain the particle physical quantity of the SPH particle at the next moment; solve the momentum equation by central difference method to obtain the particle motion equation of the finite particle method (FPM) of the slender object.

[0081] According to the displacement of the coupling unit, that is, the displacement of the slender object particle, the position of the virtual particle at the coupling interface is updated. Specifically, assuming that the distance between the virtual particle at the coupling interface and the slender object unit remains unchanged during the motion, the angle of the slender object unit's counterclockwise rotation at time t+1 is θ relative to time t. For the virtual particle B belonging to the slender object unit, i , the updated position at time t+1 for: d′=R(θ)·d, in, are the positions of the two end points of the slender object unit at time t+1, R(θ) is the rotation matrix, and d is the rotation matrix from B at time t. ip Point B i vector.

[0082] As an example, based on the interpolation principle, the partial differential equation can be converted into an integral form through the kernel estimation formula, and then the integral equation can be approximated by summing a series of discrete particle physical quantities. SPH discretizes the fluid calculation domain into a series of particles with physical information such as velocity, density, pressure, etc. The physical quantity of each particle is obtained by weighting the physical quantities of other particles in a certain area around the particle (support domain), and then discretizing the partial differential equations such as the fluid continuity equation and momentum equation into:

[0083]

[0084] Using the Lagrangian format, the motion of SPH particles represents the fluid motion.

[0085] Through the leapfrog time integration scheme, the particle properties at the next moment can be iteratively obtained from the particle position, velocity, density and other properties at the existing moment.

[0086] The particle motion equations of the finite particle method (FPM) for slender objects are obtained, including:

[0087] Assuming that the particles are in a state of dynamic equilibrium in each time iteration step during the structural deformation process, the motion of any particle follows Newton's second law, which is: m α is the mass of particle α, and They represent the external force, internal force and damping force of the particle α respectively, μ is the damping coefficient, which is a set constant; through the central difference algorithm, the displacement of the particle in the path unit is directly obtained, and the position and deformation information of the structure at the next moment are obtained.

[0088] Step 106: Distribute multiple layers of virtual particles evenly on the coupling interface using a coupling interface particle arrangement method, and determine the simulated physical quantities of the virtual particles at the coupling interface, as well as the corresponding relationship between the physical quantities, based on the transfer unit and the coupling unit. The pressure distribution transmission on the coupling interface is obtained by analyzing the transfer unit, and the displacement of the virtual particles is obtained by analyzing the coupling unit, thereby building a two-dimensional fluid-structure coupling analysis framework for slender objects.

[0089] In the embodiment of the present application, the two-dimensional fluid-structure coupling analysis framework is obtained by the aforementioned processing equations. Although the fluid-structure coupling analysis framework is obtained by simulation, it can greatly improve the calculation speed of slender beam structures and solve the fluid-structure coupling problem of large-scale slender beams.

[0090] Step 107 : Analyze the fluid-structure coupling of the slender object based on the analysis framework to obtain corresponding analysis results.

[0091] The modeling and analysis of the slender beam structure of the embodiment of the present application is based on the finite mass method. The slender beam is simulated by two-dimensional beam elements. The overall stiffness matrix does not need to be integrated, which avoids the ill-conditioned problem of the overall stiffness matrix and can effectively analyze the dynamic response of the slender beam during movement. At the same time, virtual reverse motion is used to separate the rigid body displacement to obtain the pure deformation of the structure. This method can effectively analyze the dynamic response of the unit internal force and deformation under large deformation when the slender beam structure interacts with the fluid, providing an effective analysis method for structural calculation. The fluid analysis of the present application is based on the SPH method, which is based on Lagrangian description and can simulate complex fluid flow and large deformation, track free surfaces and moving boundaries, improve numerical stability through tensile stability control, and effectively analyze the nonlinear free surface flow of fluids, providing an effective analysis method for fluid simulation. The present application proposes a two-dimensional beam element to simulate the slender beam, construct the slender beam structure with two-dimensional beam elements, and obtain the unit pure deformation and particle internal force through the virtual reverse motion of the beam element, avoiding the deformation and internal force calculation of the planar solid element and greatly reducing the complexity of the calculation. This application replaces the planar solid unit with several two-dimensional beam units. Based on the characteristics of the finite particle method that the particle motions are independent of each other and the internal force solutions of the units are independent of each other, the advantage of the finite particle method's high parallelism is brought into play. With the help of advanced parallel computing technologies such as Graphics Processing Unit (GPU) and Distributed Parallel Message Passing Interface (MPI), the calculation speed of slender beam structures can be greatly improved, and the fluid-solid coupling problem of large-scale slender beams can be solved.

[0092] It should be emphasized that, although the technical solution of the embodiment of the present application is described using a slender beam structure as an example, it is also applicable to application scenarios of other slender objects.

[0093] The following is a detailed description of the technical solutions of the embodiments of the present application.

[0094] The embodiments of the present application propose a beam structure model based on the finite particle method, a fluid model based on SPH, and interface coupling. First, the beam structure is discretized into beam particles, the slender beam is simulated by a two-dimensional beam unit, the fluid is simulated by an SPH particle, the pressure transmission of the coupling interface is simulated by a transmission unit, and the displacement coordination of the coupling interface is simulated by a coupling unit. The finite particle method is used for dynamic analysis. The deformation and rigid body displacement of the two-dimensional beam structure are obtained through virtual inverse motion analysis, and the deformation and internal force of the two-dimensional beam unit are obtained. The SPH computational fluid model is used, and the fluid continuity equation and momentum equation are discretized based on the particle approximate fluid control equation. The tensile stability control is achieved based on the ShepardFilter method and particle correction technology. The frog leaping time integration scheme is used to solve the particle physical quantities at the next moment from the particle physical quantities at the current moment to meet the requirements of numerical stability, and the minimum time step is solved according to the CFL condition. The coupling interface particle arrangement method uses uniformly distributed multi-layer virtual particles to establish the physical quantity correspondence between the virtual particles at the interface and the transfer unit and the coupling unit. The interface pressure on the virtual particles is further transferred to the beam unit particle, and the distribution and transmission of the interface pressure are obtained by analyzing the transfer unit. The virtual particles at the coupling interface update their positions according to the displacement of the beam particle, and the displacement of the virtual particles is obtained by analyzing the coupling unit. Repeat the above analysis steps to complete the analysis of the fluid-solid coupling problem of slender beams and build a two-dimensional beam fluid-solid coupling analysis framework.

[0095] In the FPM-SPH coupling analysis framework of the embodiment of the present application, for each iterative step, the structural field, flow field and fluid-solid coupling interface are calculated separately. For the structural field, the pure deformation and unit internal force of the plane beam unit are calculated based on the displacement of the beam particles and applied to the particles. For the flow field, the density change rate and velocity change rate are calculated based on the physical quantities such as the position, velocity, density and pressure of the fluid particles, so as to update the physical quantities of the fluid particles through time integration. For the coupling interface, the interface pressure of the fluid particles on the virtual particles is calculated and transmitted to the beam particles; and after the beam particle displacement is calculated based on the resultant force of the beam particles in the structural field, the virtual particle position is updated, thereby updating the flow field boundary. The following is a detailed description.

[0096] like Figure 2 As shown, let the mass points at both ends of the plane beam structure (beam unit) be A and B. a and t b (=t a +Δt), the plane positions of the two end particles are and The rotation angle positions of the two end particles are and Then the particles at both ends are a to t b The displacement and rotation angle at the moment are:

[0097]

[0098] The beam element t a , t b The positions at the two moments are recorded as AB and A′B′ respectively. To calculate the pure deformation of the beam element, the element is moved inversely according to the linear displacement between the two moments and the rotation angle between the two axes, as shown in the following example: Figure 2 As shown. The reverse translation is -Δx A , the reverse rotation amount is -θ ba After the reverse motion, A" coincides with A, and the virtual position A"B" is collinear with AB. Based on the difference between the virtual position A"B" and AB, the pure deformation of the beam element is obtained as:

[0099] Δ e =l b -l a

[0100]

[0101] In the above formula, l is the length of the beam element, Δ e is the expansion and contraction deformation of the beam element along the axial direction of the element, and are the bending deformations of the beam element at points A and B, respectively.

[0102] Under the linear elastic constitutive model, the internal force increment generated on the beam unit mass point in the AB reference configuration local coordinate system can be obtained based on the pure deformation; after obtaining the internal force increment of the beam unit, it is superimposed on t a Based on the total internal force of the reference configuration at the moment, we can get t b The total amount of internal force in this configuration at this moment. Then transform it to the global coordinate system and pass the unit forward translation Δx A and forward rotation θ ba , we get the plane beam element t b The internal force of the unit at time.

[0103] like Figure 3 As shown in Figure 1, SPH approximates the field function (and its derivatives) through the kernel function, converting it into the weighted sum of all particles in the support domain Ω (radius κh, κ is a constant, h is the kernel function radius). The field function f(x) can be approximated by the kernel function W(xx′,h) as:

[0104] <f(x)> =∫ Ω f(x′)W(xx′,h)dx′

[0105] Then the function in X i The function value at <f(x i )> can be approximated by a finite number of particles in a local area:

[0106]

[0107] where m j , ρ j are the mass and density of neighboring particle j, respectively, and N is the number of neighboring particles around particle i. Through kernel estimation and particle approximation, the continuity equation and momentum equation of the fluid can be discretized as:

[0108]

[0109] Where p i 、v i denote the pressure and velocity of particle i, v ij is the velocity of particle i relative to particle j, is the kernel function in x i The partial derivative at , Π ij is the artificial viscosity, which can be expressed as:

[0110]

[0111] In order to solve the fluid momentum equation, it is necessary to further calculate the fluid pressure. An artificial state equation is used to represent the relationship between density change and pressure, which further increases the calculation time step of the SPH method. The artificial state equation is:

[0112] p i =c i 2 (ρ i -ρ0)

[0113] Where c i is the fluid sound velocity, and ρ0 is the fluid static density.

[0114] The virtual particle method is used to process the fluid boundary. Multiple layers of virtual particles with similar mass, density and pressure are arranged at the boundary. These virtual particles participate in the calculation of the physical quantities of the fluid particles, thereby alleviating the particle inconsistency. The pressure of the virtual particles at the moving boundary is obtained by interpolation of the surrounding fluid particles:

[0115]

[0116] Where p w 、p a are the pressures of virtual particles and fluid particles, respectively, a w is the acceleration of the virtual particle, and the density of the boundary particles is inversely calculated using the artificial equation of state.

[0117] The embodiment of this application uses Shepard Filter and particle displacement correction technology to achieve tensile stability control. The Shepard Filter method corrects the density once at a certain time step, which has little effect on the SPH calculation framework. The corrected density is expressed as

[0118] in, The density is corrected at intervals of 25 time steps. Secondly, the particle displacement correction technology is used to improve the uneven distribution of particles. The displacement correction amount δx of particle i is i for:

[0119]

[0120] In the formula, the coefficient β ranges from 0.001 to 0.1, v max is the maximum velocity of the particle, Δt is the calculation time step, x ij is the distance between particles i and j, N i is the number of neighboring particles of particle i, e ij is the unit direction vector from particle i to particle j. After obtaining the particle displacement correction, it is necessary to further correct other physical quantities of the fluid particles, such as velocity, pressure, density, etc. The correction amounts are expressed as:

[0121]

[0122] like Figure 4 As shown in the figure, the number of beam particles is small and the distance between them is larger than that of fluid particles. Virtual particles with a distribution density similar to that of fluid particles are arranged along the beam axis at the coupling interface. At the same time, multiple layers of virtual particles need to be arranged to provide sufficient boundary pressure. Multiple layers of virtual particles are evenly arranged according to the size of the two-dimensional beam structure.

[0123] like Figure 5 As shown in Figure 2, the interface pressure consists of two parts: the fluid particle pressure and the coupling interface repulsion. The interface pressure acts on the virtual particles at the coupling interface, and the resultant force is for:

[0124]

[0125] Where, is the virtual particle density, m w is the mass of virtual particles; p w is the pressure of virtual particles, F ij is the coupling interface repulsion. w The pressure of the virtual particle at the moving boundary is obtained by interpolating the adjacent fluid particles. In the embodiment of the present application, when calculating the resultant force using the above formula, only the contribution from the fluid particles is considered.

[0126] On the basis of considering the pressure of fluid particles, the coupling interface repulsion is introduced to further prevent fluid particles from penetrating the coupling interface. The coupling interface repulsion is expressed as:

[0127]

[0128] In the formula Δd is the initial interval division.

[0129] Acting on virtual particle B i The interface pressure on the beam element is further transferred to the beam element mass through the transfer unit. Assuming that the relative position relationship between the plane beam element and the corresponding virtual particle always remains unchanged, the virtual particle B i The projection position of beam element A0A1 on the coupling boundary is B ip , the coupling force transmitted to the mass points at both ends of the beam element is calculated as follows:

[0130]

[0131] in The virtual particle coupling force Local coordinate system along the beam The direction component, d is the distance from the virtual particle projection point to the virtual particle, is the equivalent coupling force acting on the particle at the end of the beam, N is the shape function matrix, N1=1-3ξ 2 +2ξ 3 , N2=(ξ-2ξ 2 +ξ 3 )l,N3=3ξ 2 -2ξ 3 ,N4=(-ξ 2 +ξ 3 )l,N′ k N k The derivative of (k=1,2,3,4) with respect to ξ, l is the length of beam element A0A1, A0 to B ip length.

[0132] like Figure 6 As shown in the figure, the virtual particle at the coupling interface updates its position according to the displacement of the coupling unit (beam particle displacement). By assuming that the distance between the virtual particle at the coupling interface and the beam unit remains unchanged during the motion, the angle of the beam unit's counterclockwise rotation at time t+1 is θ relative to time t. i , the updated position at time t+1 It can be calculated as follows:

[0133]

[0134] in are the positions of the particles at both ends of the beam at time t+1, R(θ) is the rotation matrix, and d is the rotation matrix from B at time t. ip Point B i vector.

[0135] The technical solutions of the embodiments of this application establish a beam structure model based on the finite particle method and a fluid model based on SPH, which can effectively solve the dynamic response of slender beam structures and the free surface flow motion. The interface coupling solution for plane beams and SPH fluid particles in the embodiments of this application completes the analysis method for the fluid-structure coupling problem of plane beams. The model and analysis results obtained using the embodiments of this application can be directly applied to the design analysis of actual engineering applications related to fluid-structure coupling of slender beams, can realistically simulate actual conditions, provide an efficient method for engineering applications, and provide a good foundation for further expanding the application of slender components in marine engineering structures.

[0136] Figure 7 FIG. 1 shows a schematic diagram of the structure of a fluid-solid coupling analysis device for a slender object based on the finite particle method and SPH according to an embodiment of the present application. Figure 7 As shown, the fluid-structure coupling analysis device for slender objects based on the finite particle method and SPH in the embodiment of the present application includes:

[0137] A creation unit 70 is used to create a finite mass elongated object structure model and an SPH-based fluid model;

[0138] A characterization unit 71 is configured to discretize the structure of the slender object into particles for characterization based on the slender object structure model and the fluid model and in combination with the interface coupling mode between the slender object and the liquid;

[0139] a simulation unit 72 for simulating a slender object using a two-dimensional slender object unit, simulating a fluid using an SPH fluid model, simulating pressure transmission at a coupling interface between the slender object and the liquid using a transmission unit, and simulating displacement coordination at the coupling interface using a coupling unit;

[0140] A force analysis unit 73 is used to perform force analysis on discrete mass points of the slender object, obtain the virtual inverse motion separation structure deformation and rigid body displacement of the slender object, and obtain the deformation of the slender object in two dimensions and the internal force it is subjected to;

[0141] A determination unit 74 is configured to determine the particle approximate fluid governing equations, the discrete fluid continuity equation, and the momentum equation of the slender object based on the transfer unit and the SPH fluid model;

[0142] The processing unit 75 is configured to perform stretching stability control on the approximate fluid control equation based on the Shepard Filter algorithm and the particle correction technology; solve the discrete fluid continuity equation by leapfrog time integration to obtain the particle physical quantities of the SPH particle at the next moment; solve the momentum equation by central difference method to obtain the particle motion equation of the finite particle method (FPM) of the slender object;

[0143] A construction unit 76 is used to uniformly distribute multiple layers of virtual particles at the coupling interface using a coupling interface particle arrangement method, and determine the simulated physical quantities of the virtual particles at the coupling interface, as well as the corresponding relationship between the physical quantities, based on the transfer unit and the coupling unit. The pressure distribution transmission at the coupling interface is obtained by analyzing the transfer unit, and the displacement of the virtual particles is obtained by analyzing the coupling unit, thereby constructing a two-dimensional fluid-structure coupling analysis framework for slender objects.

[0144] The analysis unit 77 is used to analyze the fluid-structure coupling of the slender object based on the analysis framework to obtain corresponding analysis results.

[0145] In some executable embodiments, the force analysis unit 73 is further configured to:

[0146] By means of virtual inverse motion of the slender object, the rigid body translation and rotation of the inverse motion of the slender object are calculated;

[0147] Deduct the rigid body translation and rotation of the mass point to determine the unit deformation information of the slender object;

[0148] The unit axial force is determined by unit deformation, and the internal forces of the mass points at both ends of the slender object unit are determined based on the force balance relationship.

[0149] In some executable embodiments, the simulation unit 72 is further configured to:

[0150] Based on the interpolation principle and kernel estimation method, the partial differential equation of the SPH fluid model is converted into an integral equation. The physical quantities of discrete particles are determined based on the integral equation. The fluid calculation domain is discretized into a series of particles carrying physical information by adding the physical quantities. The physical quantity of each particle is obtained by weighting the physical quantities of other particles in a certain area around the particle.

[0151] And the attribute information of the particle at the previous moment is iteratively obtained to obtain the attribute information of the particle at the next moment.

[0152] In some executable embodiments, the building unit 76 is further configured to:

[0153] At the coupling interface, along the axis of the slender object, multiple layers of virtual particles with a distribution density similar to that of the fluid particles are arranged with the same particle spacing.

[0154] In some executable embodiments, the simulation unit 72 is further configured to:

[0155] Determine the effect on virtual particle B i The interface pressure on the virtual particle B i The interface pressure on the plane is decomposed into the mass points of the slender object unit. Specifically, it is assumed that the relative position relationship between the plane slender object unit and the corresponding virtual particle always remains unchanged. The virtual particle B i The projection position of the slender object element A0A1 on the coupling boundary is B ip , then the coupling force transmitted to the mass points at both ends of the slender object unit is in The virtual particle coupling force Along the local coordinate system of the slender object The direction component, d is the distance from the virtual particle projection point to the virtual particle, is the equivalent coupling force acting on the particle at the end of the slender object, N is the shape function matrix, N1=1-3ξ 2 +2ξ 3 , N2=(ξ-2ξ 2 +ξ 3 )l,N3=3ξ 2 -2ξ 3 ,N4=(-ξ 2 +ξ 3 )l,N′ k N k The derivative of (k=1,2,3,4) with respect to ξ, l is the length of the slender object unit A0A1, A0 to B ip The length of the slender object unit is shown in Figure 2, and A0 and A1 are the two end points of the slender object unit respectively.

[0156] In the embodiment of the present application, the position of the virtual particle at the coupling interface is updated according to the displacement of the coupling unit, that is, the displacement of the slender object particle. Specifically, assuming that the distance between the virtual particle at the coupling interface and the slender object unit remains unchanged during the movement, the angle of the slender object unit rotating counterclockwise at time t+1 relative to time t is θ, and the virtual particle B belonging to the slender object unit is i , the updated position at time t+1 for: d′=R(θ)·d, in, are the positions of the two end points of the slender object unit at time t+1, R(θ) is the rotation matrix, and d is the rotation matrix from B at time t. ip Point B i vector.

[0157] In the embodiment of the present application, the force analysis unit 73 is further used to:

[0158] Assuming that the particles are in a state of dynamic equilibrium in each time iteration step during the structural deformation process, the motion of any particle follows Newton's second law, which is: m α is the mass of particle α, and They represent the external force, internal force and damping force of the particle α respectively, μ is the damping coefficient, which is a set constant; through the central difference algorithm, the displacement of the particle in the path unit is directly obtained, and the position and deformation information of the structure at the next moment are obtained.

[0159] In an exemplary embodiment, the aforementioned units may be implemented by one or more central processing units (CPU), graphics processing units (GPU), application-specific integrated circuits (ASIC), DSPs, programmable logic devices (PLD), complex programmable logic devices (CPLD), field-programmable gate arrays (FPGA), general-purpose processors, controllers, microcontrollers (MCU), microprocessors, or other electronic components.

[0160] Regarding the device in the above embodiment, the specific manner in which each module and unit performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0161] According to an embodiment of the present application, the present application also provides an electronic device and a readable storage medium.

[0162] Figure 8 FIG. 8 is a schematic block diagram of an example network element 800 that can be used to implement an embodiment of the present application. Figure 8As shown, network element 800 includes a computing unit 801, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 802 or a computer program loaded from a storage unit 808 into a random access memory (RAM) 803. Various programs and data required for the operation of network element 800 may also be stored in RAM 803. Computing unit 801, ROM 802, and RAM 803 are connected to each other via a bus 804. An input / output (I / O) interface 805 is also connected to bus 804.

[0163] Multiple components in network element 800 are connected to I / O interface 805, including: input unit 806, such as a keyboard, mouse, etc.; output unit 807, such as various types of displays, speakers, etc.; storage unit 808, such as a magnetic disk, optical disk, etc.; and communication unit 809, such as a network card, modem, data processing transceiver, etc. Communication unit 809 allows network element 800 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0164] The computing unit 801 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of the computing unit 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The computing unit 801 performs the various methods and processes described above, such as the fluid-structure interaction analysis method for slender objects based on the finite particle method and SPH. For example, in some embodiments, the fluid-structure interaction analysis method for slender objects based on the finite particle method and SPH can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as the storage unit 808. In some embodiments, part or all of the computer program can be loaded and / or installed on the network element 800 via the ROM 802 and / or the communication unit 809. When the computer program is loaded into the RAM 803 and executed by the computing unit 801, one or more steps of the fluid-structure interaction analysis method for slender objects based on the finite particle method and SPH described above can be performed. Alternatively, in other embodiments, the computing unit 801 may be configured in any other appropriate manner (for example, by means of firmware) to execute a fluid-structure interaction analysis method for slender objects based on the finite particle method and SPH.

[0165] Various embodiments of the systems and techniques described above can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on a chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0166] The program code for implementing the methods of the present application can be written in any combination of one or more programming languages. Such program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the program code is executed by the processor or controller, the functions / operations specified in the flow charts and / or block diagrams are implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0167] In the context of the present application, a machine-readable medium can be a tangible medium that can contain or store a program for use by an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, device or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium can include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0168] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0169] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer having a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (LAN), a wide area network (WAN), and the Internet.

[0170] A computer system may include a client and a server. The client and server are generally remote from each other and typically interact through a communication network. The client-server relationship arises through computer programs running on the respective computers and having a client-server relationship with each other. The server may be a cloud server, a server in a distributed system, or a server integrated with a blockchain.

[0171] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this application can be achieved. This is not a limitation herein.

[0172] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0173] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A fluid-structure interaction analysis method for slender objects based on the finite particle method and SPH, characterized in that: Create finite particle slender object structure models and smoothed particle method (SPH)-based fluid models; Based on the slender object structure model and the fluid model, combined with the interface coupling mode between the slender object and the liquid, the slender object structure is discretized and represented by mass points; the method includes: The slender object is simulated by two-dimensional slender object units, and the fluid is simulated by the SPH fluid model. The pressure transmission at the coupling interface between the slender object and the liquid is simulated by the transmission unit, and the displacement coordination of the coupling interface is simulated by the coupling unit. The force analysis is performed on the discrete particles of the slender object to obtain the virtual inverse motion separation structural deformation and rigid body displacement of the slender object, and the deformation and internal force of the slender object in the two-dimensional direction are obtained. Determine the particle approximate fluid governing equations for slender objects based on transfer elements and SPH fluid models, and discretize the fluid continuity equation and momentum equation; The approximate fluid control equation is subjected to tensile stability control based on the Shepard Filter algorithm and particle correction technology; the discrete fluid continuity equation is solved by leapfrog time integration to obtain the particle physical quantities of the SPH particle at the next moment; the momentum equation is solved by the central difference method to obtain the particle motion equation of the finite particle method (FPM) of the slender object; A coupling interface particle arrangement method is used to evenly distribute multiple layers of virtual particles at the coupling interface. The simulated physical quantities of the virtual particles at the coupling interface, as well as the corresponding relationship between the physical quantities, are determined based on the transfer unit and the coupling unit. The pressure distribution and transmission at the coupling interface are obtained by analyzing the transfer unit, and the displacement of the virtual particles is obtained by analyzing the coupling unit, thereby establishing a two-dimensional fluid-structure coupling analysis framework for slender objects. Based on the analysis framework, the fluid-structure coupling of the slender object is analyzed to obtain corresponding analysis results.

2. The fluid-structure coupling analysis method for slender objects based on the finite particle method and SPH according to claim 1, characterized in that: The step of obtaining the virtual inverse motion of the slender object by separating the structural deformation and the rigid body displacement to obtain the deformation and internal force of the slender object in the two-dimensional direction includes: By means of virtual inverse motion of the slender object, the rigid body translation and rotation of the inverse motion of the slender object are calculated; Deduct the rigid body translation and rotation of the mass point to determine the unit deformation information of the slender object; The unit axial force is determined by unit deformation, and the internal forces of the mass points at both ends of the slender object unit are determined based on the force balance relationship.

3. The fluid-structure coupling analysis method for slender objects based on the finite particle method and SPH according to claim 1, characterized in that: The fluid simulation using the smoothed particle method (SPH) includes: Based on the interpolation principle and kernel estimation method, the partial differential equation of the SPH fluid model is converted into an integral equation. The physical quantities of discrete particles are determined based on the integral equation. The fluid calculation domain is discretized into a series of particles carrying physical information by adding the physical quantities. The physical quantity of each particle is obtained by weighting the physical quantities of other particles in a certain area around the particle. And the attribute information of the particle at the previous moment is iteratively obtained to obtain the attribute information of the particle at the next moment.

4. The fluid-structure coupling analysis method for slender objects based on the finite particle method and SPH according to claim 1, characterized in that: The method of uniformly distributing multiple layers of virtual particles on the coupling interface by using the coupling interface particle arrangement method includes: At the coupling interface, along the axis of the slender object, multiple layers of virtual particles with a distribution density similar to that of the fluid particles are arranged with the same particle spacing.

5. The fluid-structure coupling analysis method for slender objects based on finite particle method and SPH according to claim 1, characterized in that: The pressure transmission at the coupled interface between the slender object and the liquid is simulated by a transmission element, including: Determine the effect on virtual particle B i The interface pressure on the virtual particle B i The interface pressure on the plane is decomposed into the mass points of the slender object unit. Specifically, it is assumed that the relative position relationship between the plane slender object unit and the corresponding virtual particle always remains unchanged. The virtual particle B i The projection position of the slender object element A0A1 on the coupling boundary is B ip , then the coupling force transmitted to the mass points at both ends of the slender object unit is in The virtual particle coupling force Along the local coordinate system of the slender object The direction component, d is the distance from the virtual particle projection point to the virtual particle, is the equivalent coupling force acting on the particle at the end of the slender object, N is the shape function matrix, N1=1-3ξ 2 +2ξ 3 , N2=(ξ-2ξ 2 +ξ 3 )l,N3=3ξ 2 -2ξ 3 ,N4=(-ξ 2 +ξ 3 )l,N′ k N k The derivative of (k=1, 2, 3, 4) with respect to ξ, l is the length of the slender object unit A0A1, A0 to B ip The length of the slender object unit is shown in Figure 2, and A0 and A1 are the two end points of the slender object unit respectively.

6. The fluid-structure coupling analysis method for slender objects based on the finite particle method and SPH according to claim 1, characterized in that: The method further includes: updating the position of the virtual particle at the coupling interface according to the displacement of the coupling unit, that is, the displacement of the slender object particle. Specifically, assuming that the distance between the virtual particle at the coupling interface and the slender object unit remains unchanged during the movement, the angle of the slender object unit rotating counterclockwise at time t+1 relative to time t is θ, and the virtual particle B belonging to the slender object unit is updated. i , the updated position at time t+1 for: d′=R(θ)·d, in, are the positions of the two end points of the slender object unit at time t+1, R(θ) is the rotation matrix, and d is the rotation matrix from B at time t. ip Point B i vector.

7. The fluid-structure coupling analysis method for slender objects based on the finite particle method and SPH according to claim 1, characterized in that: The method of obtaining the particle motion equation of the finite particle method (FPM) of the slender object includes: Assuming that the particles are in a state of dynamic equilibrium in each time iteration step during the structural deformation process, the motion of any particle follows Newton's second law, which is: m α is the mass of particle α, and They represent the external force, internal force and damping force of the particle α respectively, μ is the damping coefficient, which is a set constant; through the central difference algorithm, the displacement of the particle in the path unit is directly obtained, and the position and deformation information of the structure at the next moment are obtained.

8. A fluid-structure coupling analysis device for slender objects based on the finite particle method and SPH, characterized in that: The device comprises: Create units for creating finite mass slender object structure models and SPH-based fluid models; a characterization unit configured to discretize the structure of the slender object into mass points for characterization based on the slender object structure model and the fluid model and in combination with an interface coupling mode between the slender object and the liquid; Simulation unit, used to simulate the slender object through the two-dimensional slender object unit, simulate the fluid through the SPH fluid model, simulate the pressure transmission of the coupling interface between the slender object and the liquid through the transmission unit, and simulate the displacement coordination of the coupling interface through the coupling unit; A force analysis unit is used to perform force analysis on discrete mass points of the slender object, obtain the virtual reverse motion separation structure deformation and rigid body displacement of the slender object, and obtain the two-dimensional deformation and internal force of the slender object; Determination unit, used to determine the particle approximate fluid governing equations of slender objects based on the transfer unit and SPH fluid model, and the discrete fluid continuity equation and momentum equation; A processing unit is configured to perform stretching stability control on the approximate fluid control equation based on a Shepard Filter algorithm and a particle correction technique; solve the discrete fluid continuity equation by a leapfrog time integration method to obtain the particle physical quantities of the SPH particle at the next moment; solve the momentum equation by a central difference method to obtain the particle motion equation of the finite particle method (FPM) of the slender object; A construction unit is used to uniformly distribute multiple layers of virtual particles at the coupling interface using a coupling interface particle arrangement method, and to determine the simulated physical quantities of the virtual particles at the coupling interface, as well as the corresponding relationship between the physical quantities, based on the transfer unit and the coupling unit. The pressure distribution transmission at the coupling interface is obtained by analyzing the transfer unit, and the displacement of the virtual particles is obtained by analyzing the coupling unit, thereby building a two-dimensional fluid-structure coupling analysis framework for slender objects. The analysis unit is used to analyze the fluid-structure coupling of the slender object based on the analysis framework to obtain corresponding analysis results.

9. The fluid-structure coupling analysis device for slender objects based on the finite particle method and SPH according to claim 8, characterized in that: The force analysis unit is further used for: By means of virtual inverse motion of the slender object, the rigid body translation and rotation of the inverse motion of the slender object are calculated; Deduct the rigid body translation and rotation of the mass point to determine the unit deformation information of the slender object; The unit axial force is determined by unit deformation, and the internal forces of the mass points at both ends of the slender object unit are determined based on the force balance relationship.

10. The fluid-structure coupling analysis device for slender objects based on the finite particle method and SPH according to claim 8, characterized in that: The simulation unit is further configured to: Based on the interpolation principle and kernel estimation method, the partial differential equation of the SPH fluid model is converted into an integral equation. The physical quantities of discrete particles are determined based on the integral equation. The fluid calculation domain is discretized into a series of particles carrying physical information by adding the physical quantities. The physical quantity of each particle is obtained by weighting the physical quantities of other particles in a certain area around the particle. And the attribute information of the particle at the previous moment is iteratively obtained to obtain the attribute information of the particle at the next moment.

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