Potential viscous flow coupling analysis method for strong nonlinear effect of real sea area wave and structure

Abstract

The invention discloses a potential viscous flow coupling analysis method for a strong nonlinear effect of a real sea area wave and a structure, and relates to the field of wave simulation and fluid-solid coupling computation.According to the method, a potential flow solver or a wave model is used for solving to obtain required wave field time calendar data, and then a dynamic coupling boundary condition and a mass flux boundary condition are used for analyzing the dynamic coupling boundary condition and the mass flux boundary condition; flow field coupling between a potential flow method and a smoothed particle fluid dynamics method is established, motion response and wave load calculation of a structure in waves are achieved, and simulation of strong nonlinear free liquid level phenomenon problems related to upward waves, slamming and the like can be achieved. According to the method, the computational domain of the smoothed particle fluid dynamic method can be remarkably reduced through the potential viscous flow coupling method, the computational efficiency is effectively improved, the quality and efficiency of wave simulation can be effectively improved, and the method is suitable for engineering application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wave simulation and fluid-structure coupling calculation, and particularly relates to a potential viscous flow coupling analysis method for strong non-linear action of real sea area wave and structure. BACKGROUND

[0002] In severe sea conditions, ships and offshore structures are prone to suffer from strong non-linear phenomena such as slamming, green water and the like, and the strong non-linear action of sea waves and structures poses a serious challenge to the safety, structural integrity and operational efficiency of the structures.

[0003] It is of great significance to numerically simulate the strong non-linear action between waves and structures in real sea areas and predict the motion response and wave load of the structures under strong non-linear free surface phenomena, for the strength design, fatigue life assessment and navigation safety warning of the structures. However, due to the complexity of such problems, the traditional hydrodynamic analysis method based on potential flow theory is difficult to accurately calculate the wave overturning and breaking, the transient load or large amplitude motion of the structure and the like. For such strong non-linear free surface problems with large deformation or even breaking of the free surface, the classical grid-based CFD (Computational Fluid Dynamics) method needs to set very fine grids near the free surface to accurately capture the evolution of the free surface, and it is difficult to accurately capture phenomena such as splashing, which is of large amount of calculation and not suitable for long-time simulation of large-scale waves, and the numerical simulation effect is not ideal. SUMMARY

[0004] In view of the above problems and technical needs, the present application provides a potential viscous flow coupling analysis method for strong non-linear action of real sea area wave and structure, and the technical scheme of the present application is as follows: A potential viscous flow coupling analysis method for strong non-linear action of real sea area wave and structure, the potential viscous flow coupling analysis method comprising: dividing a flow field calculation domain where the structure is located into a near-field calculation domain and a far-field calculation domain, the near-field calculation domain being a flow field containing a predetermined range where the structure is located, and the far-field calculation domain being a flow field adjacent to the periphery of the near-field calculation domain, and the wave propagating from a far-field incident surface of the far-field calculation domain to the near-field calculation domain; there being an overlapping coupling region between the far-field calculation domain and the near-field calculation domain, an outer boundary of the near-field calculation domain serving as an outer boundary of the coupling region, and an inner boundary of the far-field calculation domain serving as an inner boundary of the coupling region; carrying out wave simulation in the far-field calculation domain by a potential flow method or a wave model under given initial boundary conditions to obtain potential flow wave field data at a first time step; carrying out wave simulation in the near-field calculation domain by a viscous flow method under given initial boundary conditions to obtain viscous flow wave field data at the first time step; according to the potential flow wave field data at the first time step and the viscous flow wave field data at the first time step, determining a coupling region wave field data at the first time step; and The mass flux flowing through the outer boundary of the coupling region is calculated from the potential flow wave field data at each time step, and the number of fluid particles on the outer boundary of the coupling region is adjusted according to the mass flux. According to the The potential flow wave field data at the nth time step is updated by spatial interpolation to update the fluid particles in the coupling region at the nth time step. Physical properties of each time step; Using the updated fluid particles within the coupling region as boundary conditions, SPH fluid-structure interaction calculations are performed in the near-field computational domain to obtain the structure in the [missing information - likely a specific phase or time period]. Results of potential-viscosity-fluid coupling analysis at each time step.

[0005] A further technical solution involves adjusting the number of fluid particles on the outer boundary of the coupling region based on the mass flux, including: Update the mass flux grid cells on the outer boundary of the coupling region, according to the... The potential flow wave field data at the nth time step is used to calculate the first... Within the nth time step, the flow passes through any i-th time step Mass flux of each mass flux grid cell ,in, It is using the first The potential flow wave field data at the nth time step is obtained by spatial interpolation. The central node of each mass flux grid cell The speed at that point, This represents the outward normal unit vector of the mass flux grid cell. It is the time step. It is the first The area of ​​a mass flux grid cell; Calculate the first The mass flux grid cell at the th Cumulative flux value after wave action at each time step , It is the first The mass flux grid cell, after the wave action in the previous time step, at the... Cumulative flux value at the start of each time step; Based on the mass flux grid cells on the outer boundary of the coupling region at the first... The cumulative flux value after wave action at each time step adjusts the number of fluid particles on the outer boundary of the coupling region and updates the mass flux grid cells at the 1st time step. The cumulative flux value after wave action at each time step.

[0006] A further technical solution involves adjusting the number of fluid particles on the outer boundary of the coupling region and updating each mass flux grid cell in the [missing information]. The cumulative flux after each time step of wave action includes: When the The mass flux grid cell at the th Cumulative flux value after wave action at each time step At that time, in the A new fluid particle is generated at the center node of each mass flux grid cell, and the first fluid particle is updated. The mass flux grid cell at the th Cumulative flux of wave action at each time step ; When the The mass flux grid cell at the th Cumulative flux value after wave action at each time step At that time, delete the outer boundary of the coupling region that is coupled with the first The center node of each mass flux grid cell is located at the nearest fluid particle, and the first... The mass flux grid cell at the th Cumulative flux value after wave action at each time step ; in, It is the initial volume of each fluid particle.

[0007] A further technical solution involves adjusting the number of fluid particles on the outer boundary of the coupling region, including: After performing SPH fluid-structure interaction calculations and updating the physical properties of fluid particles in the near-field computational domain, out-of-bounds particles are deleted, and the nearest particle to the out-of-bounds particle is selected as the next closest particle. The mass flux grid cell at the th The cumulative flux value after wave action at each time step is updated to: Among them, out-of-bounds particles are fluid particles that move beyond the outer boundary of the coupling region. It is the initial volume of each fluid particle.

[0008] Its further technical solution is, according to the first The potential flow wave field data at the nth time step is updated by spatial interpolation to update the fluid particles in the coupling region at the nth time step. The physical properties of each time step include: The local region near the far-field computational domain within the coupling region is defined as the forced region, and other regions within the coupling region far from the far-field computational domain are defined as the buffer region. Fluid particles within the forced region are called forced particles, and fluid particles within the buffer region are called buffer particles; any fluid particle in the first... The physical properties at each time step include the fluid particles at the 1st time step. Position at each time step Particle velocity and pressure ; The first The spatial interpolation results of the potential flow wave field data at the nth time step are directly used as the forced particle at the nth time step. The updated physical properties at each time step; Using the first Spatial interpolation results of potential flow wave field data at time step and buffer particles at the . The physical properties at each time step are weighted to obtain the buffer particle at the [number]th time step. The updated physical properties at each time step.

[0009] A further technical solution is to obtain the forced particle in the first... The updated physical properties at each time step include: Using the first Spatial interpolation was performed on the potential flow wave field data at the nth time step to obtain the pre-calculated position of the forced particles. Free surface correction and particle uniformity processing were then applied to the forced particles within the coupling region to obtain the forced particle position at the nth time step. The updated position at each time step ; Using the first Spatial interpolation of potential flow wave field data at each time step yields the updated position of the forced particles. particle velocity at that location and pressure , respectively as forced particles in the , Particle velocity updated at each time step and the pressure after the update .

[0010] A further technical solution is to obtain the forced particle in the first... The updated position at each time step include: Using the first The position of the forced particle is obtained by spatial interpolation of the potential flow wave field data at each time step. particle velocity at that location And calculate the forced particle in the first Pre-calculated position at each time step , It is the time step; In the forced particle in the first Pre-calculated position at each time step Based on this, the wave height of the wave field in the coupling region is used to correct the forced particles at the free surface, and the forced particles at the non-free surface are processed to achieve uniform particle distribution, thus obtaining the forced particles at the [missing information - likely a specific location or region]. The updated position at each time step .

[0011] A further technical solution is to correct the forced particles at the free surface by using the wave height of the wave field in the coupling region, and to perform particle uniform distribution processing on the forced particles at the non-free surface, including: correcting the forced particles at the free surface to obtain the updated position of the forced particles at the free surface at the time step , is the pre-calculated position of the forced particles at the free surface at the time step wave height of the wave field at the position of the forced particles at the free surface; performing particle uniform distribution processing on the forced particles at the non-free surface to obtain the updated position of the forced particles at the non-free surface at the time step ; wherein, represents the displacement correction amount of the current forced particle, and , is the CFL number, is the Mach number, is the smoothing length, is the density of the current forced particle , is the density of the fluid particles in the support domain of the current forced particle , is the mass of the fluid particles , is the kernel function value between the current forced particle and the fluid particles in the support domain of the current forced particle , represents the spatial gradient of the position of the current forced particle , is the kernel function value of the initial particle spacing , is an empirical parameter.

[0012] A further technical solution is to obtain the updated physical properties of the buffer particles at the time step, including: spatially interpolating the potential flow wave field data at the time step to obtain the particle velocity and the pressure at the position of the buffer particles ; keeping the position of the buffer particles at the time step unchanged as the updated position , and weighting to obtain the updated particle velocity of the buffer particles at the time step The weight is obtained by buffering the particle in the first time step of the updated pressure ; wherein the weight coefficient , , represents the distance between the position of the buffering particle and the inner boundary of the coupling area in the water tank coordinate system in the direction of the axis , is the width of the buffering area in the water tank coordinate system in the direction of the axis , the direction of the axis in the water tank coordinate system is perpendicular to the two side boundaries of the coupling area.

[0013] A further technical solution is that the SPH fluid-structure coupling calculation in the near-field calculation domain comprises: solving the SPH control equation in the near-field calculation domain with the updated fluid particles in the coupling area as the boundary condition, updating the physical properties of other fluid particles in the near-field calculation domain in the first time step; based on the updated physical properties of all fluid particles in the near-field calculation domain in the first time step, obtaining the fluid acting force and the fluid acting torque exerted on the structure in the first time step; based on the fluid acting force and the fluid acting torque , obtaining the motion response of the structure in the first time step by using the rigid body motion equation of the structure.

[0014] The beneficial technical effects of the present application are: The present application discloses a potential viscous flow coupling analysis method for strong nonlinear action of real sea area waves and structures, which is based on the meshless smoothed particle hydrodynamics method, proposes dynamic coupling boundary conditions and mass flux boundary conditions, establishes the flow field coupling between the potential flow method and the smoothed particle hydrodynamics method, realizes the motion response of the structure in the waves and the wave load calculation, and can realize the simulation of strong nonlinear free surface phenomena such as green water and slamming, can significantly reduce the calculation domain of the smoothed particle hydrodynamics method, and effectively improve the calculation efficiency. At the same time, in the potential viscous flow coupling method, the generation, evolution and propagation of waves are mainly simulated by the potential flow method, compared with the simulation by the smoothed particle hydrodynamics method, the quality and efficiency of wave simulation can be effectively improved, which is suitable for engineering application. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the method flowchart of the potential viscous flow coupling analysis method of an embodiment of the present application.

[0016] Figure 2 is a schematic diagram of the division of the flow field calculation domain in which the structure is located.

[0017] Figure 3 is a schematic diagram of the distribution of fluid particles in the near-field calculation domain.

[0018] Figure 4 is a schematic diagram of the changes in the weighting coefficients of the potential flow wave field data and the physical properties of the particles with the position of the particles when updating the physical properties of the fluid particles in the coupling region.

[0019] Figure 5 is a comparison chart between the heave response results of the structure obtained by the method of the present application and the test results, the results obtained by the Euler grid method, and the results obtained by the SPH method in an example.

[0020] Figure 6 is a comparison chart between the surge response results of the structure obtained by the method of the present application and the test results, the results obtained by the Euler grid method, and the results obtained by the SPH method in an example.

[0021] Figure 7 is a comparison chart between the pitch response results of the structure obtained by the method of the present application and the test results, the results obtained by the Euler grid method, and the results obtained by the SPH method in an example.

[0022] Figure 8 is a comparison chart between the slamming load results of the structure obtained by the method of the present application and the test results, the results obtained by the Euler grid method, and the results obtained by the SPH method in an example. DETAILED DESCRIPTION

[0023] The specific embodiments of the present application will be further described below with reference to the accompanying drawings.

[0024] The present application discloses a potential viscous flow coupling analysis method for strong nonlinear action of real sea area waves and structures. The method combines the advantages of the potential flow method and the CFD method for potential viscous flow coupling analysis according to the characteristics of the two methods. The CFD method used is a meshless particle CFD method. Due to the Lagrangian property and meshless characteristics of the meshless particle CFD method, the method has certain advantages compared with the classical grid CFD method.

[0025] In order to realize high-precision coupling of flow fields between the potential flow method and the Smoothed Particle Hydrodynamics (SPH) method, and to realize the strong nonlinear free surface phenomenon problem of waves and structures in real sea areas involving upwelling and slamming, the present application includes the following steps, please refer to the flow chart shown in Figure 1 ​Step 110: Divide the flow field computation domain of the structure into a near-field computation domain. and far-field computational domain .

[0026] The structures mentioned in this application include ships and various marine structures. Please refer to [reference needed]. Figure 2 The diagram shown illustrates the near-field computational domain. This refers to the watershed containing the structure within a predetermined range, which can be customized. Far-field computational domain. It is the near-field computational domain The surrounding adjacent watershed. Waves are calculated from the far-field computational domain. Far-field incident plane near-field computational domain spread.

[0027] Far-field computational domain and near-field computational domain There are overlapping coupling regions between them, and the extent of these coupling regions can be customized. Near-field computational domain. The outer boundary is used as the outer boundary of the coupling region. Far-field computational domain The inner boundary is used as the inner boundary of the coupling region. Generally, the outer boundary of this coupling region and inner boundary All are two-dimensional planes along the vertical direction. The structure is located in the near-field computational domain. The region outside the coupling region.

[0028] Step 120, based on the near-field computational domain obtained by partitioning and far-field computational domain First, wave simulation is performed in the far-field computational domain using the potential flow method or wave model under given initial boundary values, to obtain the... Potential flow wave field data at time step n, including wave height, velocity, and pressure. For ease of subsequent calculations, the data is... Potential flow wave field data at each time step are typically output in an interpolable grid format.

[0029] Step 130, according to the first Calculation of potential flow wave field data at each time step through the outer boundary of the coupling region The mass flux is calculated, and the outer boundary of the coupling region is adjusted based on the mass flux. The number of fluid particles on the surface.

[0030] Near-field computational domain Fluid particles are distributed inside; please refer to [the relevant documentation]. Figure 3 The diagram shown illustrates the near-field computational domain. Each fluid particle in the first The physical properties at each time step are known, including those of fluid particles at the [number]th time step. Position at each time step Particle velocity and pressure The physical properties of the fluid particle in the first time step are obtained through initialization, and the physical properties of the fluid particle from the second time step onwards are calculated from the previous time step.

[0031] To achieve flow field coupling between the potential flow method and the smoothed particle hydrodynamics (SPH) method, a mass flux boundary condition is proposed. The number of fluid particles is adjusted based on the mass flux to realize mass transfer between the potential flow method and the SPH method, including the following steps: First, at the outer boundary of the coupling region Update the mass flux grid cells, and then you can determine the mass flux based on the first... The potential flow wave field data at the nth time step is used to calculate the first... Within time step, the flow passes through any i-th time step Mass flux of each mass flux grid cell The calculation formula is:

[0032] in, It is using the first The potential flow wave field data at the nth time step is obtained by spatial interpolation. The central node of each mass flux grid cell The speed at that location. This represents the outward normal unit vector of the mass flux grid cell. It is the time step. It is the first The area of ​​a mass flux grid cell.

[0033] Then calculate the first... The mass flux grid cell at the th Cumulative flux value after wave action at each time step .in, It is the first The mass flux grid cell, after the wave action in the previous time step, at the... The cumulative flux value at the start of each time step.

[0034] Finally, based on the outer boundary of the coupling region The mass flux grid cells on the first The cumulative flux value after wave action at each time step adjusts the number of fluid particles on the outer boundary of the coupling region and updates the mass flux grid cells at the 1st time step. The cumulative flux value after wave action at each time step, specifically: For any i The mass flux grid cell will be the first The mass flux grid cell at the th Cumulative flux value after wave action at each time step With the initial volume of each fluid particle Compare them.

[0035] when At that time, in the A new fluid particle is generated at the center node of each mass flux grid cell, and the first fluid particle is updated. The mass flux grid cell at the th Cumulative flux of wave action at each time step .

[0036] when At that time, delete the outer boundary of the coupling region that is coupled with the first The center node of each mass flux grid cell is located at the nearest fluid particle, and the first... The mass flux grid cell at the th Cumulative flux value after wave action at each time step .

[0037] Step 140, according to the first The potential flow wave field data at the nth time step is updated by spatial interpolation to update the fluid particles in the coupling region at the nth time step. Physical properties at each time step.

[0038] Please refer to Figure 3 Furthermore, the coupling region is divided into a forced region and a buffer region. The forced region is the area within the coupling region that is close to the far-field computational domain. The local region, the buffer region is the region within the coupling area that is far from the far-field computational domain. The sizes of the forced region and the buffer region can be customized, with the buffer region generally larger than the forced region. To facilitate differentiation, the near-field computational domain can be used. Fluid particles within the fluid are classified into three categories, such as... Figure 3 As shown, the near-field computational domain Fluid particles in the free region outside the coupling region are denoted as free particles, fluid particles in the forced region of the coupling region are denoted as forced particles, and fluid particles in the buffer region of the coupling region are denoted as buffer particles.

[0039] In utilizing the first When updating the physical properties of forced particles and buffer particles within the coupling region using potential flow wave field data at each time step, different methods are used to update the physical properties of forced particles and buffer particles, including: (1) For forced particles, directly use the first The spatial interpolation result of the potential flow wave field data at the time step is directly taken as the updated physical property of the forced particle at the time step. The spatial interpolation result of the potential flow wave field data at the time step is directly taken as the updated physical property of the forced particle at the time step.

[0040] In order to accurately reflect the dynamic coupling, the spatial interpolation is not directly performed on the position of the forced particle as its physical property, but includes the following three steps: The first step is to obtain the pre-calculated position of the forced particle by spatial interpolation using the potential flow wave field data at the time step, to preliminarily estimate the position reached by the forced particle under the action of the wave, specifically: The position of the forced particle is obtained by spatial interpolation using the potential flow wave field data at the time step , and the particle velocity at the position is calculated , and then the pre-calculated position of the forced particle at the time step is calculated . The second step is to perform free surface correction and particle uniform distribution processing on the forced particles in the coupling region to obtain the updated position of the forced particle at the time step , to ensure accurate coupling of the free surface and to prevent non-physical particle deviation. Specifically: After obtaining the pre-calculated position of the forced particle in the first step , the wave height in the coupling region is used to correct the position of the forced particle at the free surface at the time step

[0041] , and the forced particles at the non-free surface are processed by particle uniform distribution to obtain the updated position of the forced particle at the time step , and the formula is as follows: For the forced particles at the free surface, the position of the forced particles at the free surface at the time step is corrected using the wave height in the coupling region contained in the potential flow wave field data, to obtain the updated position of the forced particles at the free surface at the time step , is the wave height at the pre-calculated position of the forced particle at the free surface at the time step .

[0042] ​​​​​​​​​For forced particles at non-free liquid surfaces, particle displacement techniques are used to correct their positions to ensure uniform distribution. This improves the stability and accuracy of their use as boundary conditions in calculations. Thus, the position of the forced particles at non-free liquid surfaces is obtained in the [fifth]... The updated position at each time step .in, This represents the displacement correction amount of the currently forced particle, and:

[0043] in, For CFL numbers, Mach number, For smooth length, The current forced particle density, The current forced particle Fluid particles within the support domain density, Fluid particles quality The current forced particle and fluid particles within its supporting domain The kernel function values ​​between Indicates the current forced particle The spatial gradient of the location, It is the initial particle spacing The kernel function value.

[0044] The third step is to obtain all the forced particles in the second step. The updated position at each time step Then, using the first Spatial interpolation of potential flow wave field data at each time step yields the updated position of the forced particles. particle velocity at that location and pressure And respectively, as forced particles in the first Particle velocity updated at each time step and the pressure after the update .

[0045] (2) For buffer particles, using the first Spatial interpolation results of potential flow wave field data at time step and buffer particles at the . The physical properties at each time step are weighted to obtain the buffer particle at the [number]th time step. The updated physical properties at each time step, specifically for any buffer particle: Keep the buffer particles in the first The position of the buffer particle at the time step is taken as the updated position .

[0046] The potential flow wave field data at the time step is used to perform spatial interpolation to obtain the position of the buffer particle The particle velocity and pressure at the position of the buffer particle are obtained, and then the updated particle velocity and pressure of the buffer particle at the time step are obtained by weighting according to the following formula :

[0047] wherein the weight coefficient , and , represents the distance between the buffer particle at the position and the inner boundary of the coupling region in the water tank coordinate system axis direction, is the width of the buffer region in the water tank coordinate system axis direction. The water tank coordinate system is a common Cartesian coordinate system, and the axis direction of the water tank coordinate system is perpendicular to the two side boundaries of the coupling region and is generally along the wave propagation direction. Thus, the closer the buffer particle is to the free region, the smaller the , and the smaller the weight coefficient used, that is, the smaller the proportion of the spatial interpolation result of the potential flow wave field data used in the update, so that the buffer transition is realized. In the update process of the forced particle, the weight coefficient can also be understood as being used to weight the spatial interpolation result of the potential flow wave field data and the original physical properties according to the above form, so that when the particles at different positions in the coupling region are updated, the change of the weight coefficient is as shown in Figure 4 .

[0048] Step 150, the SPH fluid-structure coupling calculation is performed in the near-field calculation domain with the updated fluid particles in the coupling region as the boundary condition, to obtain the potential viscous flow coupling analysis result of the structure at the time step .

[0049] First, the SPH control equation is solved in the near-field calculation domain with the updated fluid particles in the coupling region as the boundary condition, to update the physical properties of other fluid particles in the near-field calculation domain at the time step .

[0050] Then, based on the updated physical properties of all fluid particles in the near-field calculation domain at the time step , the potential viscous flow coupling analysis result of the structure at the time step​ fluid force received by a fluid particle at a time step and fluid force moment When performing SPH fluid-structure interaction calculation, the main task is to solve the fluid particle force on the structure particle and the force moment on the structure, and the fluid force and the force moment are integrated to obtain the fluid force and the force moment received by the whole structure and force moment .

[0051] Finally, the physical properties of the fluid particle and the structure are updated by using the fourth-order Runge-Kutta integration, including the fluid force and fluid force moment The motion response of the structure at the first time step is obtained by using the rigid body motion equation of the structure:

[0052] wherein, is the mass of the structure, is the moment of inertia of the structure around the center of mass, is the displacement of the center of mass of the structure, is the velocity of the center of mass of the structure, is the angular displacement of the structure, is the angular velocity of the structure. is the acceleration of gravity, denotes time.

[0053] After updating the physical properties of the fluid particle and the state of the structure, the next time step is entered, and steps 120-150 are performed again, so as to obtain the motion response and impact load of the structure at different times.

[0054] In another embodiment, after completing the SPH fluid-structure interaction calculation and updating the physical properties of the fluid particle in the near-field calculation domain, that is, at the end of each time step, for the fluid particle moving to the outside boundary of the coupling region, it is called a boundary-crossing particle, and after deleting the boundary-crossing particle, the flux accumulation value of the first mass flux grid cell closest to the boundary-crossing particle after the wave action at the first time step is updated to and then the next time step is entered. In this way, through the double detection of mass flux comparison and particle boundary crossing, the coupling accuracy of the potential flow method and the SPH method can be improved.

[0055] In an example, a three-degree-of-freedom floating body is impacted by a two-dimensional focused wave, as shown in Figure 2The flow field calculation domain of the structure is a pool, and the wave is generated by the wave board on the left side of the pool and propagates to the right. During the process, the wave gradually evolves to form a focusing wave, and finally impacts on the structure to cause the phenomenon of upwelling and impact load. For such strong nonlinear free surface problems with large deformation or even breaking, the classic grid-based CFD method needs to set very fine grids near the free surface to accurately capture the evolution of the free surface, and it is difficult to accurately capture phenomena such as splashing. For the SPH method, a large amount of computing resources will be consumed in the simulation of the early wave propagation and evolution process, and the quality of wave simulation is not as good as the potential flow method. By using the potential viscous flow coupling analysis method of the present application, the SPH method is used to simulate the strong nonlinear fluid-solid coupling in the near-field calculation domain of the structure, and the high-order spectral potential flow method is used to simulate the propagation and evolution of the wave in the far-field calculation domain, which can effectively solve the above problems of simulation of strong nonlinear free surface, calculation efficiency and wave simulation quality. The comparison data of the heave response curve of the structure obtained by the potential viscous flow coupling analysis method of the present application with the test results and the results of other methods are shown in FIG. 3. Figure 5 The comparison data of the surge response curve of the structure with the test results and the results of other methods are shown in FIG. 4. Figure 6 The comparison data of the pitch response curve of the structure with the test results and the results of other methods are shown in FIG. 5. Figure 7 The comparison data of the impact load results of the structure with the test results and the results of other methods are shown in FIG. 6. Figure 8 Figures 5-8 The comparison data of the impact load results of the structure with the test results and the results of other methods are shown in FIG. 6.

[0056] The above is only the preferred embodiment of the present application, and the present application is not limited to the above embodiments. It can be understood that other improvements and changes directly derived or thought by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.​

Claims

1. A potential-viscous-current coupling analysis method for the strong nonlinear interaction between waves and structures in real sea areas, characterized in that, The potential-viscosity-fluid coupling analysis method includes: The flow field computational domain of the structure is divided into a near-field computational domain and a far-field computational domain. The near-field computational domain is the flow domain containing a predetermined range where the structure is located, and the far-field computational domain is the flow domain adjacent to the periphery of the near-field computational domain. Waves propagate from the far-field incident surface of the far-field computational domain to the near-field computational domain. There is an overlapping coupling region between the far-field computational domain and the near-field computational domain. The outer boundary of the near-field computational domain is used as the outer boundary of the coupling region, and the inner boundary of the far-field computational domain is used as the inner boundary of the coupling region. Wave simulation is performed in the far-field computational domain using the potential flow method or wave model under given initial boundary values, yielding the... Potential flow wave field data at each time step; According to the The mass flux flowing through the outer boundary of the coupling region is calculated from the potential flow wave field data at each time step, and the number of fluid particles on the outer boundary of the coupling region is adjusted according to the mass flux. According to the The potential flow wave field data at the nth time step is updated by spatial interpolation to update the fluid particles in the coupling region at the nth time step. Physical properties of each time step; Using the updated fluid particles within the coupling region as boundary conditions, SPH fluid-structure interaction calculations are performed in the near-field computational domain to obtain the structure in the [missing information - likely a specific phase or time period]. Results of potential-viscosity-fluid coupling analysis at each time step.

2. The potential-viscous-fluid coupling analysis method according to claim 1, characterized in that, Adjusting the number of fluid particles at the outer boundary of the coupling region based on mass flux includes: Update the mass flux grid cells on the outer boundary of the coupling region, according to the... The potential flow wave field data at the nth time step is used to calculate the first... Within the nth time step, the flow passes through any i-th time step Mass flux of each mass flux grid cell ,in, It is using the first The potential flow wave field data at the nth time step is obtained by spatial interpolation. The central node of each mass flux grid cell The speed at that point, This represents the outward normal unit vector of the mass flux grid cell. It is the time step. It is the first The area of ​​a mass flux grid cell; Calculate the first The mass flux grid cell at the th Cumulative flux value after wave action at each time step , It is the first The mass flux grid cell, after the wave action in the previous time step, at the... Cumulative flux value at the start of each time step; Based on the mass flux grid cells on the outer boundary of the coupling region at the first... The cumulative flux value after wave action at each time step adjusts the number of fluid particles on the outer boundary of the coupling region and updates the mass flux grid cells at the 1st time step. The cumulative flux value after wave action at each time step.

3. The potential-viscous-fluid coupling analysis method according to claim 2, characterized in that, Adjusting the number of fluid particles on the outer boundary of the coupling region and updating each mass flux grid cell in the 1st... The cumulative flux after each time step of wave action includes: When the The mass flux grid cell at the th Cumulative flux value after wave action at each time step At that time, in the A new fluid particle is generated at the center node of each mass flux grid cell, and the first fluid particle is updated. The mass flux grid cell at the th Cumulative flux of wave action at each time step ; When the The mass flux grid cell at the th Cumulative flux value after wave action at each time step At that time, delete the outer boundary of the coupling region that is coupled with the first The center node of each mass flux grid cell is located at the nearest fluid particle, and the first... The mass flux grid cell at the th Cumulative flux value after wave action at each time step ; in, It is the initial volume of each fluid particle.

4. The potential-viscous-fluid coupling analysis method according to claim 2, characterized in that, Adjusting the number of fluid particles on the outer boundary of the coupling region also includes: After performing SPH fluid-structure interaction calculations and updating the physical properties of fluid particles in the near-field computational domain, out-of-bounds particles are deleted, and the nearest particle to the out-of-bounds particle is selected as the next closest particle. The mass flux grid cell at the th The cumulative flux value after wave action at each time step is updated to: Among them, out-of-bounds particles are fluid particles that move beyond the outer boundary of the coupling region. It is the initial volume of each fluid particle.

5. The potential-viscous-fluid coupling analysis method according to claim 1, characterized in that, According to the The potential flow wave field data at the nth time step is updated by spatial interpolation to update the fluid particles in the coupling region at the nth time step. The physical properties of each time step include: The local region near the far-field computational domain within the coupling region is defined as the forced region, and other regions within the coupling region far from the far-field computational domain are defined as the buffer region. Fluid particles within the forced region are called forced particles, and fluid particles within the buffer region are called buffer particles; any fluid particle in the first... The physical properties at each time step include the fluid particles at the [number]th time step. Position at each time step Particle velocity and pressure ; The first The spatial interpolation results of the potential flow wave field data at the nth time step are directly used as the forced particle at the nth time step. The updated physical properties at each time step; Using the first Spatial interpolation results of potential flow wave field data at time step and buffer particles at the . The physical properties at each time step are weighted to obtain the buffer particle at the [number]th time step. The updated physical properties at each time step.

6. The potential-viscous-fluid coupling analysis method according to claim 5, characterized in that, The forced particle was obtained in the first The updated physical properties at each time step include: Using the first Spatial interpolation was performed on the potential flow wave field data at the nth time step to obtain the pre-calculated position of the forced particles. Free surface correction and particle uniformity processing were then applied to the forced particles within the coupling region to obtain the forced particle position at the nth time step. The updated position at each time step ; Using the first Spatial interpolation of potential flow wave field data at each time step yields the updated position of the forced particles. particle velocity at that location and pressure , respectively as forced particles in the , Particle velocity updated at each time step and the pressure after the update .

7. The potential-viscous-fluid coupling analysis method according to claim 6, characterized in that, The forced particle was obtained in the first The updated position at each time step include: Using the first The position of the forced particle is obtained by spatial interpolation of the potential flow wave field data at each time step. particle velocity at that location And calculate the forced particle in the first Pre-calculated position at each time step , It is the time step; In the forced particle in the first Pre-calculated position at each time step Based on this, the wave height of the wave field in the coupling region is used to correct the forced particles at the free surface, and the forced particles at the non-free surface are processed to achieve uniform particle distribution, thus obtaining the forced particles at the [missing information - likely a specific location or region]. The updated position at each time step .

8. The potential-viscous-fluid coupling analysis method according to claim 7, characterized in that, The wave height of the wave field within the coupling region is used to correct the forced particles at the free surface, and particle distribution processing is performed on the forced particles at the non-free surface, including: Free surface correction is performed on the forced particles at the free surface to obtain the forced particles at the free surface in the [missing information]. The updated position at each time step , The forced particles at the free surface are in the first... Pre-calculated position at each time step Wave height at the location; Forcibly distributed particles at non-free liquid surfaces are subjected to particle uniformity processing to obtain the forced particles at non-free liquid surfaces in the [number of]th [phase]. The updated position at each time step ;in, This represents the displacement correction amount of the currently forced particle, and , For CFL numbers, Mach number, For smooth length, The current forced particle density, The current forced particle Fluid particles within the support domain density, Fluid particles quality The current forced particle and fluid particles within its supporting domain The kernel function values ​​between Indicates the current forced particle The spatial gradient of the location, It is the initial particle spacing The kernel function value, These are empirical parameters.

9. The potential-viscous-fluid coupling analysis method according to claim 5, characterized in that, The buffer particles were obtained in the first... The updated physical properties at each time step include: Using the first Spatial interpolation of potential flow wave field data at each time step yields the location of the buffer particles. particle velocity at that location and pressure ; Keep the buffer particles in the first The position at each time step remains unchanged as the updated position. The weighted average of the buffer particles is obtained in the first... Particle velocity updated at each time step The weighted average of the buffer particles is obtained in the first... Pressure after each time step update Among them, the weighting coefficient , , Indicates position The buffer particles and the boundary within the coupling region in the pool coordinate system Distance along the axis The buffer zone in the pool coordinate system Width along the axis, in the pool coordinate system The axial direction is perpendicular to the two side boundaries of the coupling region.

10. The potential-viscous-fluid coupling analysis method according to claim 1, characterized in that, Performing SPH fluid-structure interaction calculations in the near-field computational domain includes: Using the updated fluid particles within the coupling region as boundary conditions, solve the SPH governing equations in the near-field computational domain, and update other fluid particles in the near-field computational domain in the [missing information]. Physical properties of each time step; Based on all fluid particles in the near-field computational domain at the first... The updated physical properties at the nth time step yield the structure at the nth time step. Fluid forces at each time step Torque of interaction with fluid ; Based on fluid forces Torque of interaction with fluid Using the rigid body motion equations of the structure, we can obtain the structure in the first... Motion response at each time step.

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