Potential flow-viscous flow real-time coupling hydrodynamic analysis method for floating body with heaving plate

Abstract

The invention belongs to the technical field of ocean engineering, and particularly relates to a potential flow-viscous flow real-time coupling hydrodynamic analysis method and system for a floating body with a heaving plate. The method comprises the following steps of: 1, establishing a free surface potential flow model based on a three-dimensional potential flow theory, simulating wave-structure interaction, ignoring a viscous effect, converting a frequency domain result of a hydrodynamic load into a time domain load through a frequency-to-hour method, and taking the time domain load as an input for solving a motion state; 2, establishing an unbounded viscous flow CFD model, viscous force not covered by a potential flow model and an updated unbounded turbulent flow field around the heaving plate, and calculating the viscous force of the heaving plate; 3, establishing an unbounded potential flow model, and separating a force component repeated with the potential flow from a viscous flow result; 4, integrating the potential flow force and the viscous force to solve a floating body motion equation, iteratively updating the motion state and feeding back the motion state to the two solvers. The method is used for solving the problems that the efficiency is correspondingly reduced if the precision is improved and the precision cannot meet the requirement if the efficiency is improved in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering technology, specifically relating to a real-time coupled hydrodynamic analysis method for potential flow and viscous flow of a floating body with a heave plate. Background Technology

[0002] In the field of marine engineering, heave plates are commonly installed at the bottom of floating production platforms and floating wind turbines to suppress heave motion. Their core function is to improve motion stability through mechanisms such as increasing added mass to lower the natural frequency of motion, inducing fluid separation and vortex shedding, dissipating kinetic energy, and providing viscous damping. Engineering practice shows that a well-designed heave plate can reduce the heave amplitude of the floating body by 30%-50%, which is crucial for ensuring the safety of deep-sea equipment operations.

[0003] Existing technologies primarily rely on two methods to simulate the hydrodynamic performance of floating bodies with heave plates: potential flow theory (PF) combined with the Morison empirical model and fully viscous computational fluid dynamics (CFD). The significant limitations of both methods are: Potential flow theory uses the boundary element method to solve the potential flow diffraction / radiation problem, and the viscous force of the heave plate is approximated by the Morison equation. However, it has significant limitations in the hydrodynamic analysis of floating structures containing heave plates. As a passive damping device, the heave plate is widely used in floating structures. However, the potential flow theory assumes that the fluid is an ideal fluid (inviscid and non-rotating), and cannot accurately capture the viscous damping and nonlinear effects caused by boundary layer separation and vortex shedding. This leads to distortions in the hydrodynamic prediction of the heave plate under large motion or complex flow fields (such as vortex-induced vibration or turbulence), especially in the amplitude and phase of the heave response. The Morison equation approximates the viscous force and added mass through the drag coefficient (Cd) and the inertia coefficient (Cm). However, these coefficients vary drastically with plate geometry, motion amplitude, Reynolds number, and flow field separation state. The empirical calibration has poor universality and usually requires calibration by CFD simulation or physical experiments, which increases the computational and experimental costs. Furthermore, it cannot describe the transient characteristics of vortex shedding, leading to large motion prediction errors. To compensate for the shortcomings of viscous effects, additional damping models (such as linear damping matrices and quadratic damping coefficients) need to be introduced, and additional mass needs to be adjusted to correct the motion period. Some studies have verified the feasibility of incorporating linear and quadratic damping models into potential flow theory through experiments and numerical methods. However, this process requires repeated parameter calibration to match experimental results. The calibration accuracy is highly dependent on empirical formulas or experimental data, lacking universality, and recalibration is required under different operating conditions, increasing the uncertainty of the analysis. In addition, when potential flow theory is combined with the Morison equation and additional damping models, it is necessary to iteratively solve the boundary element method and calibrate multiple parameters (such as Cd, Cm, and the linear damping matrix), resulting in high computational complexity, especially when dealing with complex geometry or multi-degree-of-freedom motion. Potential flow theory is based on the assumption of a linear potential function, making it difficult to accurately simulate the dynamic response of a heave plate in large-amplitude motion or strongly nonlinear flow fields, such as vortex shedding, turbulent disturbances, and nonlinear wave-current interactions. The neglect of these effects leads to significant deviations between the predicted results and actual physical experiments, especially under extreme sea conditions. Furthermore, heave plates typically possess complex geometries (such as perforated plates or irregular edges), and the boundary element method of potential flow theory suffers from limitations in mesh generation and computational accuracy when dealing with such complex boundary conditions, making it difficult to accurately describe local flow field characteristics. In summary, potential flow theory, in the hydrodynamic analysis of structures containing heave plates, fails to effectively capture viscous effects, nonlinear flow field characteristics, and the local influences of complex geometry, requiring extensive empirical parameter calibration, resulting in low computational efficiency, limited prediction accuracy, and insufficient universality. To overcome these shortcomings, it is usually necessary to combine CFD simulations or experimental data for correction, or develop efficient numerical methods that couple viscosity and potential flow to improve the accuracy and reliability of heave response prediction.

[0004] Fully viscous computational fluid dynamics (CFD) methods, by directly solving the Navier-Stokes equations, can accurately capture the viscous effects, turbulent characteristics, and nonlinear flow field behavior of fluids, thus providing physically more realistic hydrodynamic simulations. This method has significant advantages in simulating complex fluid phenomena. However, when dealing with floating structures with heave plates, CFD methods face numerous computational challenges and resource requirements. For example, capturing free surface fluctuations and heave plate separation requires a finer mesh across the entire domain, with additional mesh refinement at the free surface to track dynamic changes, leading to a surge in mesh count. Furthermore, CFD simulations are typically solved in the time domain, suitable for studying transient behavior and nonlinear effects. However, to obtain the response characteristics of the floating body across the entire frequency domain, such as the response amplitude operator (RAO), extensive time-domain simulations must be performed, followed by extraction of frequency domain information through time-frequency transformations (such as Fourier transforms). This process is computationally intensive, especially in long-term or multi-condition simulations, further increasing computational resources and time costs, thus limiting the application of CFD methods in engineering design. To improve efficiency, we can consider developing a coupling method that combines the advantages of potential flow theory and CFD to reduce reliance on time-domain simulation. Summary of the Invention

[0005] This invention provides a real-time coupled hydrodynamic analysis method for potential flow and viscous flow with a floating body equipped with a heave plate, which solves the problem in the prior art that if the accuracy is increased, the efficiency will decrease accordingly, and if the efficiency is increased, the accuracy cannot meet the requirements.

[0006] This invention provides a real-time coupled hydrodynamic analysis system for potential flow and viscous flow with a floating body equipped with a heave plate, which is used to realize a real-time coupled hydrodynamic analysis method for potential flow and viscous flow with a floating body equipped with a heave plate.

[0007] This invention is achieved through the following technical solution: A real-time coupled hydrodynamic analysis method for potential flow and viscous flow of a floating body with a heave plate, the method comprising the following steps: Step 1: Establish a free surface potential flow model based on three-dimensional potential flow theory to simulate wave-structure interaction. Ignore viscous effects and convert the hydrodynamic load from the frequency domain to the time domain using the frequency rotation time method, and use it as input for solving the motion state. Step 2: Establish an unbounded viscous flow CFD model, viscous forces not covered by the potential flow model, and an updated unbounded turbulent field around the heave plate, and calculate the viscous forces of the heave plate. Step 3: Establish an unbounded potential flow model and separate the force components that overlap with the potential flow from the viscous flow results; Step 4: Solve the equations of motion for the floating body by combining potential flow force and viscous force, iteratively update the motion state and feed it back to the two solvers.

[0008] Furthermore, step 1 specifically involves establishing a free surface potential flow model based on three-dimensional potential flow theory to simulate wave-structure interaction, importing frequency domain calculation results, and using time domain potential flow theory to calculate diffraction force, radiation force, hydrostatic restoring force, and Froude-Krylov force to simulate wave-structure interaction, neglecting viscous effects; solving for hydrodynamic loads based on the Cummins equation, and converting the frequency domain results into time domain motion state inputs using the time domain response function method.

[0009] Furthermore, in the vertical direction, the total hydrodynamic force on the floating body is calculated; the flow field is described under the assumptions of ideal fluid and small amplitude of wave excitation and object motion. The potential flow load components of the total hydrodynamic forces acting on the floating body are Froude-Krylov force, wave diffraction and radiation force, and hydrostatic restoring force. Based on the zero-speed potential flow theory, the frequency domain hydrodynamic response of a fixed floating structure is solved by the boundary element method; the time-frequency domain conversion is achieved by the Cummins impulse response function method. Under the linear assumption, the radiation force FD is calculated based on the response function.

[0010] Furthermore, step 2 specifically involves establishing an unbounded viscous flow CFD model, simulating and calculating the unbounded turbulent flow field around the heave plate using the pimpleFoam solver based on OpenFOAM, and specifically solving the viscous forces not covered by the potential flow model; updating the CFD mesh boundary conditions and mesh deformation using the motion state of the previous time step through the transmitted motion, and calculating the viscous forces of the heave plate after the flow field is updated.

[0011] Furthermore, the viscous drag acting on the heave plate is solved directly by the CFD incompressible one-way flow solver; the continuity equation and momentum equation need to be expressed in consideration of mesh deformation. The k-ω SST turbulence model was chosen; its governing equations are the turbulent kinetic energy equation and the specific dissipation rate equation. The motion of the floating body is transmitted to the mesh by solving the Laplace equation; In the CFD solver, the viscous force of the heave plate is obtained by integrating the total force on the surface of the object with the surface pressure and viscous shear stress.

[0012] Furthermore, step 3 specifically involves establishing an unbounded potential flow model to analyze the inertial reaction force caused by the motion of the object under conditions without a free surface. This model is used to separate the force components that overlap with the potential flow from the viscous flow results, ensuring the independence of the coupled solutions.

[0013] Furthermore, step 4 specifically involves employing a two-step Adams-Bashforth method for time progression. The initial motion state and force conditions of the floating body are used to calculate the load on the floating body at the next moment, and the motion state and the load magnitudes from the previous two steps are used as input variables for subsequent time step calculations.

[0014] A real-time coupled potential-viscous flow hydrodynamic analysis system with a heave plate float, the system employing the aforementioned real-time coupled potential-viscous flow hydrodynamic analysis method with a heave plate float, the system comprising: Potential flow load calculation unit on floating body: Based on three-dimensional potential flow theory, a free surface potential flow model is established to simulate wave-structure interaction. Ignoring viscous effects, the hydrodynamic load is converted from frequency domain results to time domain load through the frequency rotation time method and used as input for solving the motion state. Potential flow load calculation unit on the floating body: Establish an unbounded viscous flow CFD model, viscous forces not covered by the potential flow model, and an updated unbounded turbulent field around the heave plate to calculate the viscous forces of the heave plate. Unbounded potential flow calculation unit: Establishes an unbounded potential flow model and separates the force components that overlap with the potential flow from the viscous flow results; The unit for solving the equations of motion integrates potential flow forces and viscous forces to solve the equations of motion of the floating body, iteratively updates the motion state, and feeds it back to the two solvers.

[0015] A real-time coupled hydrodynamic analysis method for potential flow and viscous flow of a floating body with a heave plate, as described above, can provide mechanisms such as viscous damping to improve motion stability and ensure the safety of deep-sea equipment operations.

[0016] The beneficial effects of this invention are: This invention significantly improves the prediction accuracy of the hydrodynamic response of floating bodies while ensuring computational efficiency, providing reliable theoretical and numerical tools for the design and analysis of marine engineering structures.

[0017] This invention significantly reduces computation time, achieving a breakthrough advantage in computational economy while maintaining physical realism. Attached Figure Description

[0018] Figure 1 This is a flowchart of the method of the present invention.

[0019] Figure 2 These are the three sub-models of the coupling framework of this invention, namely (a) a potential flow model with a free surface; (b) a CFD model without a free surface; and (c) a potential flow model without a free surface.

[0020] Figure 3 is a schematic diagram of the CFD computation domain of the present invention, wherein Figure 3(a) is a single-flow computation domain; and Figure 3(b) is a multi-flow computation domain with a free surface.

[0021] Figure 4 shows the CFD two-phase flow solver of the present invention, wherein Figure 4(a) is compared with the potential flow-viscous flow real-time coupled single-phase flow solver; Figure 4(b) shows the mesh generation comparison.

[0022] Figure 5 is a comparison of the results after adjusting the added mass and damping coefficient using the pure potential flow method of the present invention. Figure 5(a) shows the original time-domain calculation results of the potential flow method; Figure 5(b) shows the time-domain calculation results of the potential flow method after adjusting the added mass; Figure 5(c) shows the time-domain calculation results of the potential flow method after adding secondary damping; and Figure 5(d) shows the time-domain calculation results of the potential flow method after adding linear damping.

[0023] Figure 6 This is a line graph comparing the experimental data of this invention with the calculation results of a pure CFD solver, a pure potential flow solver, and a potential flow + viscous flow real-time coupled solver.

[0024] Figure 7 This is a line graph comparing the forced oscillation simulation results of the present invention. Detailed Implementation

[0025] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0026] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0027] It should also be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0030] Implementation Method 1 This embodiment provides a real-time coupled hydrodynamic analysis method for potential flow and viscous flow of a floating body with a heave plate, the method comprising the following steps: Step 1: Establish a free surface potential flow model based on three-dimensional potential flow theory to simulate wave-structure interaction. Ignore viscous effects and convert the hydrodynamic load from the frequency domain to the time domain using the frequency rotation time method, and use it as input for solving the motion state. Step 2: Establish an unbounded viscous flow CFD model, viscous forces not covered by the potential flow model, and an updated unbounded turbulent field around the heave plate, and calculate the viscous forces of the heave plate. Step 3: Establish an unbounded potential flow model and separate the force components that overlap with the potential flow from the viscous flow results; Step 4: Solve the equations of motion for the floating body by combining potential flow force and viscous force, iteratively update the motion state and feed it back to the two solvers.

[0031] Furthermore, step 1 specifically involves establishing a free surface potential flow model based on three-dimensional potential flow theory to simulate wave-structure interaction, importing frequency domain calculation results (added mass, damping coefficient, mass matrix, hydrostatic restoring matrix, and wave force), and using time-domain potential flow theory to calculate diffraction force, radiation force (including added mass), hydrostatic restoring force, and Froude-Krylov force, etc., to simulate wave-structure interaction, neglecting viscous effects; solving for hydrodynamic loads based on the Cummins equation, and converting the frequency domain results into time-domain motion state inputs using the time-domain response function method.

[0032] Furthermore, in the potential-viscous flow coupled hydrodynamic analysis method for a floating body with a heave plate, this invention only considers the heave motion of the floating body; in the vertical direction, the total hydrodynamic force on the floating body can be expressed as... (1) Wherein, FPF is the potential flow load, and FCFD is the viscous force calculated by the CFD solver; In step (1), under the assumptions that the fluid is an ideal fluid and the amplitudes of wave excitation and object motion are small, the flow field can be described by the Laplace equation satisfied by the velocity potential φ: (2) The potential flow load component in equation (1) is composed of the following equation: (3) Among them, the four mechanical components are: PFE is the total external force, FF-K is the Froude-Krylov force; FD and FR are the wave diffraction and radiation forces; and FHS is the hydrostatic restoring force. Based on the zero-speed potential flow theory, the frequency domain hydrodynamic response of a fixed floating structure is solved using the boundary element method; time-frequency domain conversion is achieved using the Cummins impulse response function method; the formulas for calculating the Froude-Krylov force and diffraction force are as follows: (4) (5) in, and The amplitudes of the Froude-Krylov force and the diffraction force at the wave frequency ω are given. and Phase angle; Under the linear assumption, the radiation force FD is calculated from the response function; its expression is: (6) in, Additional mass at infinite frequency; response function The expression is: (7) in, The heave radiation damping coefficient; The formula for calculating the hydrostatic restoring force FHS is: (8) in, The still water restoring stiffness coefficient, This represents the heave displacement of the floating body; Based on the above description of the potential flow load components, equation (1) can be expressed as follows: (9) Where FW is the wave excitation force, expressed as: (10)

[0033] Furthermore, step 2 specifically involves establishing an unbounded viscous flow CFD model, simulating and calculating the unbounded turbulent flow field around the heave plate using the pimpleFoam solver based on OpenFOAM, and specifically solving the viscous forces not covered by the potential flow model; updating the CFD mesh boundary conditions and mesh deformation using the motion state (acceleration, velocity, displacement) of the previous time step through the transmitted motion, and calculating the viscous forces of the heave plate after the flow field is updated.

[0034] Furthermore, the viscous drag acting on the heave plate is directly solved by the CFD incompressible one-way flow solver; considering mesh deformation, the continuity equation and momentum equation are expressed by the following formulas: (11) (12) in, For the velocity field, For mesh deformation rate, For dynamic pressure, Effective viscosity; The k-ω SST turbulence model is selected; its governing equations are the turbulent kinetic energy (k) equation and the specific dissipation rate (ω) equation, expressed as follows: (13) (14) The motion of the floating body is transferred to the mesh by solving the Laplace equation: (15) in, For the mesh deformation displacement field, The grid motion diffusion coefficient is determined using the inverse distance weighting method. In a CFD solver, the viscous force on a heave plate is calculated by integrating the total force on the surface of the object with the surface pressure and viscous shear stress. Its mathematical expression is as follows: (16) in, For fluid density, Let the area vector of the face elements be . For pressure, The coefficient of dynamic viscosity, It is the deviatoric stress tensor.

[0035] Furthermore, step 3 specifically involves establishing an unbounded potential flow model to analyze the inertial reaction force (an additional mass force proportional to acceleration) caused by the motion of an object under conditions without a free surface. This is used to separate the force components that overlap with the potential flow from the viscous flow results, ensuring the independence of the coupled solution.

[0036] Furthermore, the establishment of the unbounded potential flow model, (17) in, Add mass to the heave in infinite water depth. Let be the vertical acceleration of the floating body; finally, the equation of motion for the floating body is expressed as: (18)

[0037] Furthermore, step 4 specifically involves using a two-step Adams-Bashforth method for time advancement.

[0038] The initial time steps are calculated using the first-order Euler method during the initialization phase. t 1's motion state y 1:

[0039] in, The total load at time t0; from t n ( n ≥1) Begin by using the load data F from the first two steps. n and F n-1 Update your exercise status:

[0040] This invention is conceptually sound, and the proposed coupled solution method innovatively integrates the advantages of potential flow theory and viscous flow CFD methods. A modular solution framework developed based on the OpenFOAM platform enables real-time data interaction between the two types of solvers, significantly improving the prediction accuracy of the hydrodynamic response of floating bodies while ensuring computational efficiency. This provides a reliable theoretical and numerical tool for the design and analysis of marine engineering structures. In this invention, experimental data on the free decay of heave motion in the Spar model are selected as a control to compare the accuracy of pure CFD solvers, pure potential flow solvers, and the real-time coupled potential flow-viscous flow solution method developed in this invention with the experimental data. Based on the experiment, the Spar model cylinder is selected with a diameter of 0.1m, a total length of 0.485m, and a draft of 0.385m. The heave plate is located at the bottom of the cylinder, with a diameter of 0.15m and a thickness of 3mm.

[0041] In the numerical calculation of free decay, an initial rise displacement of 0.055 m was selected based on experiments. Pure CFD, pure potential flow, and viscous-potential coupled computational domains were established, as shown in Figure 3, with a domain length of 7 m. The background mesh size was kept consistent, and the mesh refinement around the Spar model was the same. Due to the difference in the free liquid surface, the total number of meshes in the CFD two-phase flow computational domain was 4.72 million (Figure 4(a)), while the viscous-potential coupled computational domain used a single-phase flow solver with a total of 99,000 meshes (Figure 4(b)). As mentioned earlier, the pure potential flow method cannot accurately capture viscous effects, requiring the introduction and repeated calibration of parameters to match experimental results. This process included adjusting the added mass to correct the motion period, adding a linear damping matrix, and adding Morrison rods to compensate for the secondary damping coefficient. Specific trial results are shown in Figure 5.

[0042] Based on multi-condition experimental verification ( Figure 6 The potential-viscous flow-viscous flow real-time coupling method proposed in this study is comparable to traditional CFD in terms of prediction accuracy of heave response, but significantly reduces computation time, achieving a breakthrough advantage in computational economy while maintaining physical realism.

[0043] Furthermore, to verify the accuracy of the proposed real-time coupling method between potential flow and viscous flow, forced oscillation simulations were performed on the Spar model using both the traditional CFD solution method and this coupling method. Thanks to the unique advantages of this coupling method, the potential flow load and viscous flow load experienced by the floating body during its motion can be analyzed separately, and their superposition yields the total hydrodynamic load.

[0044] The potential flow load and viscous flow load components calculated by the coupling method have clear physical meanings, and the total load-time history curve after their superposition is comparable to the results of traditional CFD solvers. Figure 7 As shown, the forced oscillation frequency is 4.9 rad / s, and the amplitude is 0.075 m. Simulation results show that the total load history curve obtained by the coupling method is in high agreement with the traditional CFD method. This comparison fully verifies the feasibility and accuracy of the coupling method in different application scenarios. In addition, the coupling method can clearly separate the contributions of potential flow and viscous effects, providing a clearer physical insight for the optimized design of the heave plate.

[0045] Implementation Method 2 This embodiment provides a real-time coupled potential-viscous flow hydrodynamic analysis system with a heave plate float. The system uses the real-time coupled potential-viscous flow hydrodynamic analysis method with a heave plate float as described in Embodiment 1. The system includes... Potential flow load calculation unit on floating body: Based on three-dimensional potential flow theory, a free surface potential flow model is established to simulate wave-structure interaction. Ignoring viscous effects, the hydrodynamic load is converted from frequency domain results to time domain load through the frequency rotation time method and used as input for solving the motion state. Potential flow load calculation unit on the floating body: Establish an unbounded viscous flow CFD model, viscous forces not covered by the potential flow model, and an updated unbounded turbulent field around the heave plate to calculate the viscous forces of the heave plate. Unbounded potential flow calculation unit: Establishes an unbounded potential flow model and separates the force components that overlap with the potential flow from the viscous flow results; The unit for solving the equations of motion integrates potential flow forces and viscous forces to solve the equations of motion of the floating body, iteratively updates the motion state, and feeds it back to the two solvers.

[0046] Implementation Method 3 This embodiment provides a real-time coupled hydrodynamic analysis method for a floating body with a heave plate, as described in Embodiment 1, which can provide mechanisms such as viscous damping to improve motion stability and ensure the safety of deep-sea equipment operations.

Claims

1. A real-time coupled hydrodynamic analysis method for potential flow and viscous flow of a floating body with a heave plate, characterized in that, The method includes the following steps: Step 1: Establish a free surface potential flow model based on three-dimensional potential flow theory to simulate wave-structure interaction. Ignore viscous effects and convert the hydrodynamic load from the frequency domain to the time domain using the frequency rotation time method, and use it as input for solving the motion state. Step 2: Establish an unbounded viscous flow CFD model, viscous forces not covered by the potential flow model, and an updated unbounded turbulent field around the heave plate, and calculate the viscous forces of the heave plate. Step 3: Establish an unbounded potential flow model and separate the force components that overlap with the potential flow from the viscous flow results; Step 4: Solve the equations of motion for the floating body by combining potential flow force and viscous force, iteratively update the motion state and feed it back to the two solvers.

2. The method according to claim 1, characterized in that, Step 1 specifically involves establishing a free surface potential flow model based on three-dimensional potential flow theory to simulate wave-structure interaction, importing frequency domain calculation results, and using time domain potential flow theory to calculate diffraction force, radiation force, hydrostatic restoring force, and Froude-Krylov force to simulate wave-structure interaction while ignoring viscous effects; solving for hydrodynamic loads based on the Cummins equations, and converting the frequency domain results into time domain motion state inputs using the time domain response function method.

3. The method according to claim 2, characterized in that, In the vertical direction, calculate the total hydrodynamic force on the floating body; describe the flow field under the assumptions of ideal fluid and small amplitude of wave excitation and object motion; The potential flow load components of the total hydrodynamic forces acting on the floating body are Froude-Krylov force, wave diffraction and radiation force, and hydrostatic restoring force. Based on the zero-speed potential flow theory, the frequency domain hydrodynamic response of a fixed floating structure is solved by the boundary element method. Time-frequency domain conversion is achieved using the Cummins impulse response function method; Under the linear assumption, the radiation force FD is calculated based on the response function.

4. The method according to claim 1, characterized in that, Step 2 specifically involves establishing an unbounded viscous flow CFD model, simulating and calculating the unbounded turbulent field around the heave plate using the pimpleFoam solver from OpenFOAM, and specifically solving for the viscous forces not covered by the potential flow model. By using the transmitted motion and the motion state of the previous time step, the CFD mesh boundary conditions and mesh deformation are updated. After the flow field is updated, the viscous force of the heave plate is calculated.

5. The method according to claim 4, characterized in that, The viscous drag acting on the heave plate is solved directly by the CFD incompressible one-way flow solver; the continuity equation and momentum equation need to be expressed in consideration of mesh deformation; The k-ω SST turbulence model was chosen; its governing equations are the turbulent kinetic energy equation and the specific dissipation rate equation. The motion of the floating body is transmitted to the mesh by solving the Laplace equation; In the CFD solver, the viscous force of the heave plate is obtained by integrating the total force on the surface of the object with the surface pressure and viscous shear stress.

6. The method according to claim 1, characterized in that, Step 3 specifically involves establishing an unbounded potential flow model to analyze the inertial reaction force caused by the motion of the object under conditions without a free surface. This is used to separate the force components that overlap with the potential flow from the viscous flow results, ensuring the independence of the coupled solution.

7. The method according to claim 6, characterized in that, Specifically, step 4 involves using the two-step Adams-Bashforth method for time propagation; calculating the load on the float at the next moment using the initial motion state and force conditions of the float, and using the motion state and the load magnitudes of the previous two steps as variable inputs for subsequent time step calculations.

8. A real-time coupled hydrodynamic analysis system for potential flow and viscous flow with a heave plate float, characterized in that, The system uses a real-time coupled potential flow-viscous flow hydrodynamic analysis method for a floating body with a heave plate as described in any one of claims 1-7, and the system comprises, Potential flow load calculation unit on floating body: Based on three-dimensional potential flow theory, a free surface potential flow model is established to simulate wave-structure interaction. Ignoring viscous effects, the hydrodynamic load is converted from frequency domain results to time domain load through the frequency rotation time method and used as input for solving the motion state. Potential flow load calculation unit on the floating body: Establish an unbounded viscous flow CFD model, viscous forces not covered by the potential flow model, and an updated unbounded turbulent field around the heave plate to calculate the viscous forces of the heave plate. Unbounded potential flow calculation unit: Establishes an unbounded potential flow model and separates the force components that overlap with the potential flow from the viscous flow results; The unit for solving the equations of motion integrates potential flow forces and viscous forces to solve the equations of motion of the floating body, iteratively updates the motion state, and feeds it back to the two solvers.

9. A real-time coupled hydrodynamic analysis method for a floating body with a heave plate as described in any one of claims 1-4 can provide mechanisms such as viscous damping to improve motion stability and ensure the safety of deep-sea equipment operations.

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