CN-122021376-A - CFD-based wave glider multi-body dynamics simulation method and system

CN122021376ACN 122021376 ACN122021376 ACN 122021376ACN-122021376-A

Abstract

The invention discloses a wave glider multi-body dynamics simulation method and system based on CFD, the method comprises the steps of adopting a centralized mass method to establish an umbilical cable flexible dynamics equation, taking a floating body and a submerged dynamics equation as boundary conditions to obtain a wave glider rigid-flexible coupling dynamics model with umbilical cable flexible, constructing a geometric model of the floating body, the submerged body and a hydrofoil, creating a background fluid domain, carrying out regional division on the background fluid domain and the geometric model by using Boolean operation, constructing a wave glider CFD simulation model with hydrofoil-seawater bidirectional fluid-solid coupling, constructing a MATLAB-Fluent based collaborative simulation interface, carrying out time domain collaborative simulation and iterative update based on the collaborative simulation interface to obtain power data in the wave glider operation process, and introducing flexible effects of the umbilical cable and the hydrofoil into the wave glider dynamics model, realizing high-precision fluid-solid coupling of seawater and structure based on CFD, and improving the motion and dynamic behavior prediction precision in the wave glider operation process.

Inventors

SHI SHAOYU
Xu Chuojie
LI XINGRAN
BAO YUCHENG
LIU JINGXI
ZHOU WEIXIN

Assignees

华中科技大学

Dates

Publication Date: 20260512
Application Date: 20251210

Claims (10)

1. The wave glider multi-body dynamics simulation method based on CFD is characterized by comprising the following steps: s1, constructing rigid body dynamics equations of a floating body and a submerged body based on a Newton-Euler method and combining a calculation formula of wave force and wind resistance, adopting a centralized mass method to construct an umbilical cable flexible dynamics equation, and taking the floating body and the submerged body dynamics equation as boundary conditions to obtain a rigid-flexible coupling dynamics model of the wave glider with umbilical cable flexibility; S2, constructing a geometric model of a floating body, a submerged body and a hydrofoil, creating a background fluid domain, carrying out region division on the background fluid domain and the geometric model by using Boolean operation, carrying out grid division by adopting a mixed grid scheme taking a hexahedron as a core, carrying out regional grid encryption and grid independence verification, and further constructing a wave glider CFD simulation model of hydrofoil-seawater bidirectional fluid-solid coupling; S3, configuring a physical model for the hydrofoil-seawater bidirectional fluid-solid coupled wave glider CFD simulation model, defining boundary conditions, and setting dynamic grid parameters to adapt to the motions of the floating body, the submerged body and the hydrofoil; S4, constructing a MATLAB-Fluent-based co-simulation interface, wherein the co-simulation interface comprises a co-simulation communication mechanism and a time synchronization mechanism; and S5, executing time domain co-simulation and iterative updating based on the co-simulation interface to acquire power data in the operation process of the wave glider, wherein the power data comprise displacement, speed, acceleration and stress data of the floating body and the submerged body in six degrees of freedom.
2. The CFD-based wave glider multi-body dynamics simulation method is characterized in that in the step S1, the umbilical cable flexible wave glider rigid-flexible coupling dynamics model uses an umbilical cable flexible body dynamics equation set as a calculation frame, uses the floating body rigid body dynamics equation set and the submerged body rigid body dynamics equation set as boundary conditions, and adopts a fourth-order range-Kutta method to solve, wherein the fourth-order range-Kutta method has the following calculation formula: ; In the formula, Refers to the estimation of acceleration using the slope of different time steps, The time step is represented by a time step, For the current time step Time value of (2); A speed estimation value representing a current time step and a next time step; is a functional expression of a kinetic equation.
3. The CFD-based wave glider multi-body dynamics simulation method of claim 2, wherein the umbilical cable flexible wave glider rigid-flexible coupling dynamics model in step S1 comprises a floating body rigid body dynamics equation set, a submerged body rigid body dynamics equation set and an umbilical cable flexible body dynamics equation set; The floating body rigid body dynamics equation set and the submerged body rigid body dynamics equation set are established based on Newton-Euler equations and are respectively used for describing six-degree-of-freedom motion of the floating body under the condition of being excited together with the umbilical cable and six-degree-of-freedom motion of the submerged body under the condition of being excited together with the fluid and the umbilical cable; The umbilical cable flexible body dynamics equation set is constructed by adopting a centralized mass method, the umbilical cable is discretized into a form that a limited number of elastic micro-sections are mutually hinged, the tension force of the micro-sections is used as a continuity condition, and each elastic micro-section follows the principle that the mass and the stress are intensively acted on a hinging point, so that the spatial pose and the internal force of the umbilical cable at any moment are obtained, and the motion transmission between the floating body and the submerged body is realized.
4. The CFD-based wave glider multi-body dynamics simulation method according to any one of claims 1-3, wherein the umbilical cable flexible wave glider rigid-flexible coupling dynamics model in the step S1 uses the tension between two nodes as a continuity condition, and the calculation expression of the tension is as follows: ; In the formula, For the tension of the micro-segment, Is the modulus of elasticity of the umbilical, Is the sectional area of the elastic micro-segment after deformation, Is the line strain of the elastic micro-segment, For the initial length of the elastic micro-segment, Is the length of the elastic micro-segment after deformation; Cross-sectional area of deformed elastic micro-segment The calculation formula of (2) is as follows: ; Wherein, the Is the section area of the elastic micro-segment when the elastic micro-segment is not deformed; line strain of the elastic micro-segment The calculation formula of (2) is as follows: ; In the formula, Is the coordinates of two mutually adjacent hinge points.
5. The wave glider multi-body dynamics simulation method based on CFD according to any one of claims 1-3, wherein the wave glider CFD simulation model of hydrofoil-sea water bidirectional fluid-solid coupling in step S2 comprises a hydrofoil bidirectional fluid-solid coupling model, a floating body unidirectional fluid-solid coupling model and a submerged body unidirectional fluid-solid coupling model, The hydrofoil bidirectional fluid-solid coupling model is used for simulating the elastic deformation of the hydrofoil under the action of fluid and the reaction of the hydrofoil on a flow field, receiving the hydrofoil motion state at each time step, calculating the unsteady hydrodynamic load, and feeding back the load to update the hydrofoil deformation and motion; The floating body unidirectional fluid-solid coupling model and the submerged body unidirectional fluid-solid coupling model respectively take the motion states of the floating body and the submerged body as input, calculate the hydrodynamic force of the corresponding structure through CFD, and feed the hydrodynamic force back to the rigid-flexible coupling dynamic model.
6. The CFD-based wave glider multi-body dynamics simulation method according to claim 5, wherein the specific configuration of the mixed grid scheme in the step S2 is that hexahedral grids are adopted in a main flow area of a background fluid area, tetrahedral or prismatic grids are adopted in geometrically complex areas of a floating body, a submerged body and a hydrofoil, and the zonal grid encryption comprises zonal grid encryption of boundary layer areas of the floating body and the submerged body, vortex areas, geometrically complex areas and surfaces, vortex areas, front and rear edge areas of the hydrofoil.
7. A CFD-based wave glider multi-body dynamics simulation method according to any of claims 1-3, wherein the physical model configuration of the CFD simulation model in step S3 comprises an incompressible flow model, a k- ε turbulence model and a VOF model, and the boundary conditions of the CFD simulation model comprise a velocity inlet, a pressure outlet, a symmetry plane and a moving wall condition.
8. The wave glider multi-body dynamics simulation method based on CFD according to any one of claims 1-3, wherein the co-simulation communication mechanism in step S4 comprises a MATLAB dynamics solving master control end and a Fluent solving client end, wherein, The MATLAB dynamics solving master control end is realized in a MATLAB environment and is used for integrating a solving algorithm of the rigid-flexible coupling dynamics model, a fourth-order Runge-Kutta method is called to perform time domain integration on dynamics equations of the floating body, the submerged body and the umbilical cable, six-degree-of-freedom motion states of the floating body and the submerged body at the current moment are sent to the Fluent solving client, and a coupling simulation flow is scheduled; the Fluent solving client is realized through a Fluent user-defined function and a schema script expansion function, and is used for receiving the motion state, driving the dynamic grid to update, executing CFD calculation, extracting hydrodynamic data and feeding back to the MATLAB dynamics solving main control end.
9. The CFD-based wave glider multi-body dynamics simulation method of claim 8, wherein the time synchronization mechanism in step S4 is characterized in that a MATLAB dynamics solving master control end uniformly manages a global simulation clock, and the method specifically comprises the following steps: s41, a MATLAB dynamics solving master control end transmits six-degree-of-freedom motion states of a floating body and a submerged body at the current moment to a Fluent solving client end, and after the Fluent solving client end receives the motion states, a single-step CFD calculation is started to finish unsteady flow field solving and output hydrodynamic data; S42, suspending solving by the Fluent solving client, and returning the hydrodynamic data to the MATLAB dynamics solving main control end; And S43, updating the dynamics states of the floating body, the submerged body and the umbilical cable by the MATLAB dynamics solving main control end based on the hydrodynamic data, pushing the global time step, and returning to the step S41 to enter the next simulation cycle.
10. The wave glider multi-body dynamics simulation system based on CFD is characterized by being used for realizing the wave glider multi-body dynamics simulation method based on CFD as claimed in any one of claims 1-9, and comprises a rigid-flexible coupling dynamics model construction module, a CFD geometric and grid modeling module, a CFD physical and boundary condition configuration module, a collaborative simulation interface construction module and a time domain collaborative simulation and data acquisition module; the rigid-flexible coupling dynamics model construction module is used for constructing rigid body dynamics equations of the floating body and the submerged body based on a Newton-Euler method and combining a calculation formula of wave force and wind resistance; The CFD geometric and grid modeling module is used for constructing geometric models of a floating body, a submerged body and a hydrofoil in a Solidworks environment, and importing Fluent software, creating a background fluid domain in the Fluent software, and carrying out region division on the background fluid domain and the geometric models by using Boolean operation; The CFD physical and boundary condition configuration module is used for configuring a physical model for the hydrofoil-seawater bidirectional fluid-solid coupled wave glider CFD simulation model, defining boundary conditions, and setting dynamic grid parameters in Fluent software to adapt to the motions of the floating body, the submerged body and the hydrofoil; The collaborative simulation interface building module is used for building a collaborative simulation interface based on MATLAB-Fluent to realize real-time data interaction and solution control between the rigid-flexible coupling dynamics model of the umbilical cable flexible wave glider and the CFD simulation model; the time domain co-simulation and data acquisition module is used for executing time domain co-simulation and iterative updating based on the co-simulation interface to acquire power data in the operation process of the wave glider.

Description

CFD-based wave glider multi-body dynamics simulation method and system Technical Field The invention belongs to the technical field of wave glider dynamics modeling and simulation, and particularly relates to a CFD-based wave glider multi-body dynamics simulation method and system. Background With the continuous upgrading of requirements such as deep open sea exploration, resource development, marine environment monitoring and the like, an unmanned observation platform with complex marine environment adaptability and long-term autonomous operation capability becomes a core research and development direction in the field of marine engineering. The wave glider is used as novel ocean unmanned mobile observation equipment, has the core advantages that the wave energy is converted into driving energy through a unique rigid-flexible coupling multi-body structure (an underwater floating body, an underwater submerged body, an umbilical cable for connecting the two and a submerged body-carried hydrofoil), further has ultra-long endurance potential, and can be widely applied to scenes such as open sea meteorological observation, water quality monitoring, submarine topography exploration and the like. However, research and performance prediction of the motion mechanism of the wave glider in the current engineering field still mainly depend on a traditional multi-rigid-body dynamics model, and hydrodynamic parameters are obtained by adopting an empirical formula for estimation, so that the method has obvious technical limitations, and is difficult to meet the requirements of high-precision design and performance optimization, and the specific problems are as follows: The traditional model simplifies the umbilical cable and the hydrofoil into rigid components, and can not effectively characterize the flexible deformation (such as stretching, bending and torsion) of the umbilical cable in the marine environment and the elastic deformation of the hydrofoil under the action of fluid load, so that the rigid-flexible coupling characteristic of the system is ignored, and the nonlinear dynamic behavior of the wave glider in actual operation is difficult to be truly reflected, such as the influence of dynamic tension fluctuation of the umbilical cable on the motion cooperativity of the floating submarine, the change of the deformation of the hydrofoil on the propulsion efficiency and the like. The fluid-solid coupling precision is insufficient, an empirical formula can only roughly estimate the hydrodynamic force (such as wave force and viscous resistance) between the sea water and a structure, and cannot accurately capture the microscopic process (such as boundary layer separation, vortex evolution and mutual interference of the wave and the structure) of the fluid-solid coupling in an unsteady flow field, so that the motion response of a floating body in the wave, the prediction deviation of the hydrodynamic load of a submerged body and a hydrofoil are larger, and the optimization design of the structural parameters (such as the length of an umbilical cable and the attack angle of the hydrofoil) of the wave glider and the accurate formulation of a control strategy are directly restricted. Therefore, it is difficult to provide a simulation scheme of the dynamics of the wave glider, which combines physical reality and prediction precision, and a simulation method capable of effectively fusing a flexible effect and high-precision fluid-solid coupling is needed, so that reliable numerical support is provided for development, performance optimization and engineering application of the wave glider. Disclosure of Invention Aiming at the defects or improvement demands of the prior art, the invention provides a CFD-based wave glider multi-body dynamics simulation method and system, which are characterized in that a rigid-flexible coupling dynamics model containing an umbilical cable flexible body dynamics equation set (a flexible micro-segment hinging mode is adopted for dispersing umbilical cables by adopting a centralized mass method to effectively characterize flexible deformation and dynamic tension transmission) is constructed, and the CFD simulation model of hydrofoil-seawater bidirectional fluid-solid coupling and floating body and submerged body unidirectional fluid-solid coupling is combined, so that a fluid-solid coupling microscopic process in an unsteady flow field is accurately captured, a hydrodynamic high-precision calculation is realized by replacing an empirical formula, the dynamic model and the CFD model real-time data interaction is realized by relying on MATLAB-Fluent collaborative simulation interfaces, the physical reality and motion state of the wave glider motion simulation is remarkably improved, the prediction precision of the hydrodynamic load is remarkably improved, meanwhile, the flow field and environment load parameters are flexibly adjusted to adapt to different ocean working conditions, the dynamic be