Sph-dem based fluid-structure-anchor chain coupling calculation method for floating wind power

Abstract

The application provides a floating wind power multi-field coupling calculation method based on SPH-DEM, and belongs to the field of ocean wind power engineering. The method simulates the hydrodynamics of seawater by SPH, analyzes the contact mechanics behavior of the floating body and the anchor chain by DEM, integrates the MoorDyn module to calculate the anchor chain tension, and constructs a fluid-structure-anchor chain coupling framework. The implementation includes: establishing the SPH and DEM models, setting the boundary and initial parameters; using GPU parallel technology to perform fluid, structure and anchor chain simulation; realizing multi-physical field coupling through data interaction, and dynamically adjusting the step length to ensure the stability of the calculation combined with the CFL criterion. Compared with the CFD and FEM methods, the method has both efficiency and accuracy, is suitable for response analysis and stability evaluation of floating wind power in extreme sea conditions, and the innovation lies in breaking through the multi-scale coupling calculation problem and realizing the collaborative calculation of the structure and the mooring system in a complex sea area.

Description

Technical Field

[0001] This invention relates to a calculation method, and more particularly to a floating wind current body-structure-anchor chain coupling calculation method based on SPH-DEM. Background Technology

[0002] Floating wind power systems are subjected to complex hydrodynamic effects in deep-sea environments, and their stability and reliability directly affect the operating efficiency and lifespan of the wind turbines. Traditional CFD methods require frequent mesh reconstruction when dealing with large deformations on free liquid surfaces, resulting in low computational efficiency; while FEM methods struggle to simulate the discrete particle contact and fracture behavior of anchor chains. Current technologies lack an efficient and unified numerical framework for the fully coupled simulation of fluid-structure-anchor chain interaction. Therefore, there is an urgent need for an efficient computational method capable of simultaneously simulating the interactions between fluid, structure, and anchor chains. Summary of the Invention

[0003] The purpose of this invention is to provide a floating wind current fluid-structure-anchor chain coupled calculation method based on SPH-DEM, so as to solve the problem that the existing technology lacks an efficient and unified numerical framework for the full coupling simulation of fluid-structure-anchor chain.

[0004] To achieve the above objectives, the specific plan is as follows:

[0005] A calculation method for floating wind power volume-structure-anchor chain coupling based on SPH-DEM includes the following steps:

[0006] S1: Establish a fluid domain and wave simulation calculation model based on the SPH method, and set the initial boundary conditions and physical parameters;

[0007] S2: Determine the parameters of the SPH fluid model, and in each main time step, the SPH module calculates the fluid pressure, density and velocity field, and outputs the hydrodynamic force applied to the surface of the floating body;

[0008] S3: The DEM module receives hydrodynamic data and the anchor chain tension from the previous step, updates the linear and rotational motion states of the floating body, and outputs the displacement information of the structural connection points to obtain the SPH-DEM coupled model.

[0009] S4: The MoorDyn module calculates the anchor chain node response and tension based on the positional changes of the floating body connection point, and feeds the tension back to the DEM module, forming a mechanical coupling closed loop DEM-MoorDyn between the structure and the anchor chain.

[0010] S5: Each module iterates and updates within the current time step until the error convergence condition is met; then the whole thing advances to the next time step, repeating steps S2-S4. During this process, the control program judges whether the state changes of each module meet the error convergence criterion. If not, it triggers local iteration of the current step; if converged, it proceeds to S6.

[0011] S6: Continuously execute steps S2 to S5 throughout the entire simulation cycle. After each time step, the system records key physical quantities, including the fluid pressure field, the anchor chain tension of the floating body's motion trajectory, and the node positions. Within each main time step, after satisfying the error convergence criterion of structural displacement increment and anchor chain tension change, proceed to the next time step. When the total simulation time reaches the preset period T... total After termination, the system finally outputs key response data including the floating body attitude, water flow field, and anchor chain tension.

[0012] Furthermore, in step S1, the steps for establishing the fluid domain and wave simulation calculation model are as follows:

[0013] S1a: Set rigid body boundary conditions to set the floating structure and anchor points of the wind power platform as movable rigid body boundaries.

[0014] S2a: Set the DEM rigid particle distribution, and set DEM particle units in the area where the floating structure and anchor chain are connected.

[0015] S3a: Set the boundary conditions for the SPH method, setting the seabed, the lower structural surface of the wind power platform and the sidewalls of the computational domain as solid wall boundaries; the sea surface as a free surface; and the outer contour of the floating body as a movable rigid body boundary.

[0016] S4a: Set the distribution of SPH particles, define the closed area enclosed by the water surface and bottom as a water body, and fill the water body with SPH particles;

[0017] S5a: Based on the STL structural model or CAD geometric information, extract the overall mass, center of mass position and moment of inertia of the floating body, and import these parameters into the calculation model as the initial properties of the floating body rigid body.

[0018] Furthermore, in step S2, the SPH fluid model parameters include pressure, density, acceleration, and smooth length, wherein the smooth length is determined by a multiple of the average spacing between fluid particles.

[0019] Furthermore,

[0020] The formula for calculating fluid pressure is:

[0021]

[0022] The formula for calculating density is:

[0023]

[0024] The formula for calculating the rate of change of density is:

[0025]

[0026] The formula for calculating fluid acceleration is:

[0027] .

[0028] Further, in step S2, a kernel function support domain is established in the SPH fluid model, and the Wendland kernel function is used for particle interpolation; wherein, the size of the kernel function support domain is determined according to the smooth length of the fluid particles, and the Wendland kernel function is:

[0029] .

[0030] Furthermore, the SPH-DEM coupled calculation method satisfies the Courant-Friendrich-Lewy criterion for its time step:

[0031]

[0032]

[0033]

[0034]

[0035] Furthermore, the DEM and MoorDyn achieve bidirectional data exchange through a coupling interface; the cable segment node tension output by MoorDyn is applied to the corresponding DEM particle position, realizing the transmission of force to the DEM system; and the force result of the particle under the action of fluid and contact affects the cable segment force and motion trajectory in reverse, forming a coupled feedback closed loop.

[0036] Furthermore, the operation steps of the calculation method provided by the present invention are as follows:

[0037] S1c: The main control process. In each main time step, the SPH module updates the velocity, pressure, and position of fluid particles and calculates the boundary hydrodynamics. The DEM module receives the fluid force provided by SPH and the anchor chain tension from the previous step, and updates the position and attitude of the float. The MoorDyn module calculates the anchor chain node response and tension based on the motion state of the float's anchor chain connection points. Finally, the MoorDyn output tension is fed back to the DEM module to complete the dynamic closed loop. Subsequently, the DEM module receives the hydrodynamics from the SPH module and the anchor chain tension from the previous time step, propels the linear and rotational response of the float, updates the structural position and attitude, and extracts the spatial state of the float's connection points as the input of MoorDyn.

[0038] S2c: Time step coordination mechanism, the system completes multiple anchor chain iterations within the main time step, and synchronizes to the SPH-DEM framework through interpolation and state updates;

[0039] S3c: Error control and convergence criterion. The system sets convergence thresholds for structural displacement increments and anchor chain tension changes. If the thresholds are exceeded, the local coupling iteration of the current time step is triggered until the error condition is met.

[0040] S4c: Output control. After each effective time step is completed, the system outputs the current fluid state, structural state, and anchor chain tension data.

[0041] Furthermore, the SPH module can be executed in parallel on the GPU through the CUDA framework, the DEM module supports parallel advancement of multiple rigid bodies, and the MoorDyn module runs on an independent thread. The three modules advance synchronously under the coordination of the main control scheduler, which improves the calculation speed and ensures the calculation accuracy.

[0042] In summary, the present invention has the following advantages over the prior art:

[0043] This invention proposes a computational method based on SPH-DEM coupling. It uses the meshless SPH method to solve for seawater flow and the DEM method to simulate the dynamic response of the anchor chain, constructing a complete fluid-structure-anchor chain coupled computational framework. This method is applicable to the simulation of floating wind turbines under different wind and wave conditions, including static equilibrium analysis, dynamic response simulation, and extreme condition testing, improving computational accuracy and stability. Specifically:

[0044] (1) This invention achieves asynchronous parallel collaborative computing of SPH, DEM and MoorDyn modules on GPU, making full use of the physical independence of each module, which significantly improves the coupling simulation efficiency of floating wind power system under complex sea conditions and meets the actual needs of large-scale, high-precision engineering simulation.

[0045] (2) Achieving high-precision dynamic coupling modeling of fluid-structure-anchor chain in floating wind power system: This invention constructs a unified meshless SPH-DEM coupling framework, which can realistically reflect the bidirectional feedback relationship between fluid impact, structural response and anchor chain tension, effectively improving simulation accuracy and the ability to evaluate the dynamic stability of floating platform, and is particularly suitable for safety analysis under extreme working conditions. Attached Figure Description

[0046] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0047] Figure 1This is a flowchart of the fully coupled fluid-structure-anchor chain calculation process for a floating wind power system based on SPH-DEM in this invention.

[0048] Figure 2 This is a schematic diagram of the support domain and particle interpolation principle of the Wendland kernel function in the SPH method of this invention;

[0049] Figure 3 This is a schematic diagram illustrating the interaction between the contact force and fluid force of the anchor chain particles in this invention;

[0050] Figure 4 This is a schematic diagram of the floating wind current body-structure-anchor chain coupling in this invention. Detailed Implementation

[0051] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0052] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form may also include the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0053] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0054] See Figure 1As shown, this invention provides a floating wind-current body-structure-anchor chain coupling calculation method based on SPH-DEM. The SPH method simulates seawater flow, the DEM method describes the local contact and motion behavior of the floating body-anchor chain connection area, and the MoorDyn module is integrated to simulate the dynamic response of the anchor chain system, achieving unified coupled modeling of the three physical processes. The specific steps of the method provided by this invention are as follows:

[0055] S1: Establish a fluid domain and wave simulation calculation model based on the SPH method;

[0056] As a preferred embodiment, in step S1, the steps for establishing the fluid domain and wave simulation calculation model are as follows:

[0057] S1a: Set rigid body boundary conditions: Set the floating structure and anchor points of the wind power platform as movable rigid body boundaries to support interaction with fluid particles and anchor chain tension input.

[0058] S2a: Set DEM rigid body particle distribution: Set DEM particle units in the area where the floating structure and the anchor chain are connected to describe the local force response and contact characteristics of the anchor chain action point, and provide interface support for subsequent DEM-MoorDyn coupling.

[0059] S3a: Set boundary conditions for the SPH method: Set the seabed, the lower structural surface of the wind power platform and the sidewall of the computational domain as solid boundaries; set the sea surface as a free surface; set the outer contour of the floating body as a movable rigid body boundary.

[0060] S4a: Set SPH particle distribution: Define the enclosed area formed by the water surface and bottom as a water body, and fill the water body with SPH particles.

[0061] S5a: Based on the STL structural model or CAD geometric information, extract the overall mass, center of mass position and moment of inertia of the floating body, and import these parameters into the calculation model as the initial properties of the floating body rigid body.

[0062] S2: Determine the parameters of the SPH fluid model, and in each main time step, the SPH module calculates the fluid pressure, density and velocity field, and outputs the hydrodynamic force applied to the surface of the floating body;

[0063] Determine the parameters of the SPH fluid model; the fluid parameters include pressure, density, acceleration, and smoothing length, etc. The smoothing length is determined by a multiple of the average spacing between fluid particles.

[0064] The formula for calculating fluid pressure is:

[0065]

[0066] In the formula, For artificial sound speed, The value is usually 7.

[0067] In the SPH method, the density of fluid particles is calculated using a density estimation formula, and the density change is updated using a continuity equation; the density calculation is determined by the following formula:

[0068]

[0069] In the formula: Let be the density of the i-th particle. Let be the mass of the j-th particle. This is the weighting function between particles.

[0070] In fluid dynamics calculations, the mass conservation equation is used to calculate the rate of density change, and it is determined by the following formula:

[0071]

[0072] In the formula, For the first The rate of change of density of each particle and Let be the velocities of the i-th and j-th particles, respectively. This is the gradient of the inter-particle weighting function.

[0073] Meanwhile, to describe the dynamic behavior of the fluid, the fluid acceleration is calculated using the SPH discrete form of the Navier-Stokes equations and determined by the following formula:

[0074]

[0075] In the formula, For the first The acceleration of each particle and Let be the pressures of the i-th and j-th particles, respectively. and Let the densities of the i-th and j-th particles be denoted as . is the viscous stress term, and g is the acceleration due to gravity.

[0076] As a preferred option, such as Figure 2 As shown, in the SPH fluid model, a kernel function support domain is established, and the Wendland kernel function is used for particle interpolation. The size of the kernel function support domain is determined based on the smooth length of the fluid particles to ensure computational accuracy and stability. The Wendland kernel function is:

[0077]

[0078] In the formula, The normalized distance between particles r and r'; It is a normalization factor, which equals [the normalization factor] in a two-dimensional problem. In a three-dimensional problem, it equals .

[0079] S3: The DEM module receives hydrodynamic data and the previous anchor chain tension, updates the linear and rotational motion state of the float, and outputs the displacement information of the structural connection points.

[0080] The DEM module calculates that the anchor chain connection point is discretized into several equivalent spherical particles. Particle properties include mass, radius, stiffness, damping, and coefficient of friction. The motion of each particle is governed by Newton's second law, and its dynamic equation can be expressed as:

[0081]

[0082] In the formula, Indicates particle mass. For particle velocity, For contact force, For fluid drag force, For pressure gradient force, This is an additional external force from MoorDyn.

[0083] Contact force Using the Hertz contact model, the normal contact force is calculated as follows:

[0084]

[0085] In the formula, For normal force, For normal stiffness, This is the normal overlap.

[0086] Contact stiffness Determined based on the material's elastic modulus and geometric properties:

[0087]

[0088] In the formula, For the equivalent elastic modulus, The equivalent radius.

[0089] The damping term is determined according to the critical damping model:

[0090]

[0091] In the formula, The normal damping coefficient is... For equivalent quality.

[0092] The tangential contact force adopts a spring-damped model and considers the Coulomb friction condition:

[0093]

[0094] In the formula, For tangential contact force, The coefficient of friction, For tangential stiffness, For tangential displacement, The tangential damping coefficient is... The tangential relative velocity.

[0095] To achieve coupling with the fluid, the particle is simultaneously subjected to a pressure gradient force obtained by SPH interpolation and a fluid drag force. The pressure gradient force is expressed as:

[0096]

[0097] In the formula, For particle volume, This represents the local pressure gradient.

[0098] The drag force is estimated using the Morison formula as follows:

[0099]

[0100] In the formula, For fluid density, The drag coefficient, The projected area of ​​the particle facing the wind. This refers to the local flow velocity.

[0101] As a preferred method, the SPH-DEM coupled calculation method satisfies the Courant-Friendrich-Lewy (CFL) criterion for time step size:

[0102]

[0103]

[0104]

[0105]

[0106] In the formula, It is on the order of 10 -1 The coulomb number; Considering it from the perspective of force; This is an option that takes into account the CFL condition and the viscosity term constraint; These are terms obtained under DEM stability constraints.

[0107] S4: The MoorDyn module calculates the anchor chain node response and tension based on the positional changes of the floating body connection point, and feeds the tension back to the DEM module, forming a closed loop of mechanical coupling between the structure and the anchor chain.

[0108] like Figure 3 As shown, the anchor chain system is directly connected to the specified rigid body boundary of the floating structure via the MoorDyn module. The nodal tensions calculated by MoorDyn are automatically applied to the floating body's center of mass or specified connection points, achieving dynamic coupling between the floating body and the anchor chain. In the MoorDyn section, the anchor chain is simplified to a concentrated mass cable segment, and the forces between the cable segment nodes are updated using the elastic tension formula. Node The equation of motion is:

[0109]

[0110] In the formula, For node quality, For node position, , The tension between adjacent nodes, For gravity, It refers to fluid force.

[0111] Cable segment tension is calculated using the following expression:

[0112]

[0113] In the formula, The elastic modulus of the material. The cross-sectional area of ​​the cable segment. This is the initial length of the cable segment. , These are the locations of the nodes at both ends of the cable segment.

[0114] S5: Each module iterates and updates within the current time step until the error convergence condition is met; then the whole thing advances to the next time step, repeating steps S2 to S4 to couple control and time advancement. During this process, the control program determines whether the state changes of each module meet the error convergence criteria. If not, it triggers local iteration of the current step; if converged, it proceeds to S6.

[0115] The DEM and MoorDyn exchange data bidirectionally via a coupling interface. The cable segment node tension output by MoorDyn is applied to the corresponding DEM particle location, realizing the transmission of force to the DEM system; while the force result of the particle under fluid and contact action affects the cable segment force and motion trajectory in turn, forming a coupled feedback closed loop.

[0116] As a preferred method, the velocity and position of the particles are updated using Verlet integrals or a predictor-corrector scheme during time progression. This is calculated using the following formula:

[0117]

[0118]

[0119] In the formula, and The velocities at time steps (n+1 and n) are respectively. and These are the positions at time steps n+1 and n, respectively. For time step.

[0120] S6: Continuously execute steps S2 to S5 throughout the entire simulation cycle. After each time step, the system records key physical quantities, including the fluid pressure field, the anchor chain tension of the floating body's motion trajectory, and the node positions. Within each main time step, after satisfying the error convergence criterion of structural displacement increment and anchor chain tension change, proceed to the next time step. When the total simulation time reaches the preset period T... total After termination, the system finally outputs key response data including the floating body attitude, water flow field, and anchor chain tension.

[0121] As a preferred embodiment, when using the calculation method provided by this invention:

[0122] S1c: Main Control Flow: Within each main time step, the SPH module sequentially updates the velocity, pressure, and position of fluid particles and calculates the boundary hydrodynamics; the DEM module receives the fluid forces provided by SPH and the anchor chain tension from the previous step, updating the float's position and attitude; the MoorDyn module calculates the anchor chain node response and tension based on the motion state of the float's anchor chain connection points; finally, the MoorDyn output tension is fed back to the DEM module, completing the dynamic closed loop. Subsequently, the DEM module receives the hydrodynamics from the SPH module and the anchor chain tension from the previous time step, propels the float's linear and rotational responses, updates the structural position and attitude, and extracts the spatial state of the float's connection points as input to MoorDyn.

[0123] S2c: Time step coordination mechanism: Since the MoorDyn module usually uses a smaller inner step size, the system completes multiple anchor chain iterations within the main time step and synchronizes to the SPH-DEM framework through interpolation and state updates.

[0124] S3c: Error control and convergence criteria: The system sets convergence thresholds for structural displacement increments and anchor chain tension changes. If the thresholds are exceeded, the local coupling iteration of the current time step is triggered until the error condition is met.

[0125] S4c: Output control: After each effective time step is completed, the system outputs the current fluid state, structural state, and anchor chain tension data.

[0126] To improve overall solution efficiency, this computational method supports a parallel computing structure between modules. The SPH module can be executed in parallel on the GPU via the CUDA framework, the DEM module supports parallel progression of multiple rigid bodies, and the MoorDyn module runs on an independent thread. The three modules are synchronized under the coordination of the main control scheduler, which improves both computational speed and accuracy.

[0127] The boundary treatment adopts the Modified Dynamic Boundary Condition (mDBC) method, which effectively enhances the accuracy of fluid-boundary interaction by arranging fixed boundary particles around the solid boundary and generating virtual particles by mirroring.

[0128] Example:

[0129] Taking the fluid-structure-anchor chain coupling response calculation of a floating wind power system as an example, the calculation method based on SPH-DEM coupling proposed in this invention is used for simulation. First, the STL geometric model of the floating structure is imported and set as a movable rigid body boundary. Multiple DEM particles are arranged at its bottom to describe the contact response of the anchor chain connection area. A water particle filling region is set up to construct a seawater SPH particle field, and the solid wall boundary and free liquid surface are defined.

[0130] In the fluid module, the pressure, density, and velocity changes of seawater particles are calculated based on the SPH method and applied to the outer wall of the float, forming a fluid load. In the structure module, the rigid float moves under the combined action of fluid forces and anchor chain tension, and its attitude changes are solved using the DEM module. The anchor chain system is connected to the float via the MoorDyn module, realizing tension transmission and dynamic response feedback.

[0131] During the simulation, the SPH module outputs fluid forces, the DEM module updates the float state, and the MoorDyn module calculates the anchor chain response and feeds back the tension based on the float connection point positions, achieving fully coupled calculation of the fluid-structure-anchor chain three fields. Taking the instantaneous data at the 20th second as an example, the tensions of the three anchor chains are as follows: anchor chain 1 tension is 1.33N, anchor chain 2 tension is 1.58N, and anchor chain 3 tension is 1.77N. These data reflect the stress state of the system at that moment. The system progresses with a unified time step, iterates until convergence, and then proceeds to the next calculation, finally outputting the float displacement, fluid velocity field, and anchor chain tension at each time point, simulating the dynamic response process under the entire working condition.

[0132] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the coupling of floating wind current, structure, and anchor chain based on SPH-DEM, characterized in that, Including the following steps: S1: Establish a fluid domain and wave simulation calculation model based on the SPH method, and set the initial boundary conditions and physical parameters; S2: Determine the parameters of the SPH fluid model, and in each main time step, the SPH module calculates the fluid pressure, density and velocity field, and outputs the hydrodynamic force applied to the surface of the floating body; S3: The DEM module receives hydrodynamic data and the anchor chain tension from the previous step, updates the linear and rotational motion states of the floating body, and outputs the displacement information of the structural connection points to obtain the SPH-DEM coupled model. S4: The MoorDyn module calculates the anchor chain node response and tension based on the positional changes of the floating body connection point, and feeds the tension back to the DEM module, forming a mechanical coupling closed loop DEM-MoorDyn between the structure and the anchor chain. S5: Each module iterates and updates within the current time step until the error convergence condition is met; then the whole thing advances to the next time step and repeats steps S2 to S4. During this process, the control program judges whether the state changes of each module meet the error convergence criterion. If not, it triggers local iteration of the current step; if convergence is achieved, it proceeds to S6. S6: Continuously execute steps S2 to S5 throughout the entire simulation cycle. After each time step, the system records key physical quantities, including the fluid pressure field, the anchor chain tension of the floating body's motion trajectory, and the node positions. Within each main time step, after satisfying the error convergence criterion of structural displacement increment and anchor chain tension change, proceed to the next time step. When the total simulation time reaches the preset period T... total After termination, the system finally outputs key response data including the floating body attitude, water flow field, and anchor chain tension. The final output key response results are: floating body attitude, water flow field, and anchor chain tension.

2. The floating wind power fluid-structure-anchor chain coupling calculation method based on SPH-DEM according to claim 1, characterized in that, In step S1, the steps for establishing the fluid domain and wave simulation calculation model are as follows: S1a: Set rigid body boundary conditions to set the floating structure and anchor points of the wind power platform as movable rigid body boundaries. S2a: Set the DEM rigid particle distribution, and set DEM particle units in the area where the floating structure and anchor chain are connected. S3a: Set the boundary conditions for the SPH method, setting the seabed, the lower structural surface of the wind power platform and the sidewalls of the computational domain as solid wall boundaries; the sea surface as a free surface; and the outer contour of the floating body as a movable rigid body boundary. S4a: Set the distribution of SPH particles, define the closed area enclosed by the water surface and bottom as a water body, and fill the water body with SPH particles; S5a: Based on the STL structural model or CAD geometric information, extract the overall mass, center of mass position and moment of inertia of the floating body, and import these parameters into the calculation model as the initial properties of the floating body rigid body.

3. The floating wind power fluid-structure-anchor chain coupling calculation method based on SPH-DEM according to claim 1, characterized in that, In step S2, the SPH fluid model parameters include pressure, density, acceleration, and smooth length, wherein the smooth length is determined by a multiple of the average spacing between fluid particles.

4. The floating wind power fluid-structure-anchor chain coupling calculation method based on SPH-DEM according to claim 3, characterized in that: The formula for calculating fluid pressure is: The formula for calculating density is: The formula for calculating the rate of change of density is: The formula for calculating fluid acceleration is: 。 5. The floating wind power fluid-structure-anchor chain coupling calculation method based on SPH-DEM according to claim 1, characterized in that, In step S2, a kernel function support domain is established in the SPH fluid model, and particle interpolation is performed using the Wendland kernel function; wherein, the size of the kernel function support domain is determined according to the smooth length of the fluid particles, and the Wendland kernel function is: 。 6. The floating wind power fluid-structure-anchor chain coupling calculation method based on SPH-DEM according to claim 1, characterized in that, The SPH-DEM coupled calculation method satisfies the Courant-Friendrich-Lewy criterion for its time step: 。 7. The floating wind power fluid-structure-anchor chain coupling calculation method based on SPH-DEM according to claim 1, characterized in that, The DEM and MoorDyn exchange data bidirectionally via a coupling interface. The cable segment node tension output by MoorDyn is applied to the corresponding DEM particle position, realizing the transmission of force to the DEM system. Meanwhile, the force result of the particle under fluid and contact influences the cable segment force and motion trajectory in reverse, forming a coupled feedback closed loop.

8. The floating wind power fluid-structure-anchor chain coupling calculation method based on SPH-DEM according to any one of claims 1 to 7, characterized in that, The operation steps of the calculation method provided by this invention are as follows: S1c: The main control process. In each main time step, the SPH module updates the velocity, pressure, and position of fluid particles and calculates the boundary hydrodynamics. The DEM module receives the fluid force provided by SPH and the anchor chain tension from the previous step, and updates the position and attitude of the float. The MoorDyn module calculates the anchor chain node response and tension based on the motion state of the float's anchor chain connection points. Finally, the MoorDyn output tension is fed back to the DEM module to complete the dynamic closed loop. Subsequently, the DEM module receives hydrodynamic data and anchor chain tension from the SPH module, propels the linear and rotational responses of the float, updates the structural position and attitude, and extracts the spatial state of the float connection points as input to MoorDyn. S2c: Time step coordination mechanism, the system completes multiple anchor chain iterations within the main time step, and synchronizes to the SPH-DEM framework through interpolation and state updates; S3c: Error control and convergence criterion. The system sets convergence thresholds for structural displacement increments and anchor chain tension changes. If the thresholds are exceeded, the local coupling iteration of the current time step is triggered until the error condition is met. S4c: Output control. After each effective time step is completed, the system outputs the current fluid state, structural state, and anchor chain tension data.

9. The floating wind power fluid-structure-anchor chain coupling calculation method based on SPH-DEM according to claim 8, characterized in that, The SPH module can be executed in parallel on the GPU through the CUDA framework, the DEM module supports parallel advancement of multiple rigid bodies, and the MoorDyn module runs on an independent thread. The three modules advance synchronously under the coordination of the main control scheduler, which improves the calculation speed and ensures the calculation accuracy.

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