CFD (computational fluid dynamics) method-based seaplane gas-water power decoupling cooperative solving method and asynchronous coupling and high-fidelity simulation method thereof under unsteady condition

Abstract

The invention discloses a CFD (computational fluid dynamics) method-based seaplane gas-water power decoupling cooperative solving method and an asynchronous coupling and high-fidelity simulation method thereof under an unsteady condition, belongs to the technical field of ship engineering structure aerodynamic force and water power calculation, and aims to solve the problem that in the prior art, when solving the problem of hydroplaning of a seaplane, the problem of the prior art is solved. And pneumatic and hydrodynamic loads need to be solved at the same time. According to the method, aerodynamic force is solved by adopting a single-phase flow solver, and unsteady aerodynamic responses of wings and a fuselage of the seaplane during hydroplaning are captured; a two-phase flow solver is adopted to simulate the nonlinear hydrodynamic behavior of the fuselage of the seaplane in waves; a single-phase flow solver based on aerodynamic force and a two-phase flow solver based on hydrodynamic force are iterated on different time steps for decoupling cooperative solution, and the stress characteristic and motion response of a seaplane under the wave working condition are accurately simulated.

Description

Technical Field

[0001] This invention belongs to the field of aerodynamic and hydrodynamic calculation technology of ship engineering structures, specifically involving a CFD-based decoupled co-solution method for the aerodynamic and hydrodynamic processes of seaplanes and its asynchronous coupling and high-fidelity simulation method under unsteady conditions. Background Technology

[0002] With the development of the marine economy, seaplanes are gradually returning to the public eye due to their outstanding waterborne performance. A seaplane is an aircraft capable of taking off and landing on water, its unique design enabling safe operation in waters without traditional runways. Its main features include a special hull structure, typically employing floats or a boat-shaped fuselage to provide buoyancy and stability on the water. This design allows seaplanes to take off and land on lakes, rivers, and oceans, greatly expanding their range of applications, especially useful in remote or airport-less areas. However, due to the complex and variable operating environment, particularly in waters with strong winds and waves, waves significantly affect their stability and safety. Therefore, assessing the seaplane's response characteristics and stresses under different wave conditions—i.e., "wave resistance"—is a crucial aspect of design and operational safety assurance. Only by accurately analyzing its forces and motion response in waves can the structural design be optimized, improving its seaworthiness and mission execution capabilities in complex sea conditions.

[0003] In the study of seaplane motion performance and wave resistance, early research mainly focused on a large number of model tests, summarizing test data and performing regression analysis to obtain semi-empirical formulas for predicting hydrodynamic performance. Subsequently, a large amount of theoretical research applied ship hydrodynamic calculation theories based on conventional ship types, such as the slice method, boundary element method, 2D+T method, and direct solution of the Navier-Stokes equations, to the solution of high-speed gliding motion problems.

[0004] While these methods have laid the foundation for research, they remain insufficient in addressing the unique challenges of seaplane motion in waves. Crucially, the dynamic behavior of seaplanes in waves is profoundly influenced by the complex coupling between hydrodynamic and aerodynamic forces, making their design and analysis far more complex than that of conventional fixed-wing aircraft.

[0005] This complexity manifests itself in several ways: aerodynamic analysis requires the construction of fine meshes to accurately resolve boundary layers, and the computational convergence process is extremely sensitive to residuals and turbulence models; hydrodynamic analysis, on the other hand, requires the use of the VOF (Volume of Fluid) method to capture free surface deformation, which necessitates the use of extremely small time steps limited by the CFL number to maintain numerical stability under explicit schemes. Coupled computation of both (i.e., jointly solving for gas-water multiphase incompressible flow under a unified mesh and time step) will lead to a surge in computational resources, decreased stability, and convergence difficulties, making it unsuitable for multi-parameter design optimization or rapid engineering evaluation.

[0006] To address this problem, a decoupled hydrodynamic and aerodynamic numerical analysis framework has been proposed for analyzing the waterborne takeoff process of amphibious aircraft. This framework uses FLUENT and ANSYS CFX to calculate hydrodynamic and aerodynamic forces respectively, and couples them at the end of each time step. This framework significantly improves computational efficiency through decoupling while maintaining high accuracy. However, it does not address the seakeeping performance of seaplanes in complex sea conditions. Summary of the Invention

[0007] This invention provides a decoupled and collaborative solution method for the air-water dynamics of seaplanes based on CFD, which solves the problem that existing methods cannot balance computational efficiency and accuracy when solving hydrodynamic problems.

[0008] This invention provides an asynchronous coupling and high-fidelity simulation method for aerodynamic and hydrodynamic effects under unsteady conditions, which is implemented by a CFD-based aerodynamic-hydrodynamic decoupling and collaborative solution method for seaplanes.

[0009] This invention is achieved through the following technical solution: A CFD-based method for decoupling and co-solving the aero-hydrodynamics of seaplanes, the method comprising: A single-phase flow solver is used to solve the aerodynamic forces, capturing the unsteady aerodynamic response of the wing and fuselage of a seaplane during gliding on water. A two-phase flow solver was used to analyze the nonlinear hydrodynamic behavior of the seaplane fuselage in waves. A decoupled and collaborative solution is achieved by using a single-phase flow solver based on aerodynamics and a two-phase flow solver based on hydrodynamics iteratively at different time steps to accurately simulate the force characteristics and motion response of a seaplane under wave conditions.

[0010] Furthermore, the governing equations of the single-phase flow solver are as follows: (1) (2) (3) in: For velocity field; For pressure; The density of the gas; This is the vector of gravitational acceleration; For temperature.

[0011] Furthermore, the governing equations of the two-phase flow solver are as follows: (4) (5) in: It is the fluid dynamic pressure; The density of a liquid or gas; It is the acceleration due to gravity; For velocity field; This refers to the grid movement speed; This refers to the surface tension term in a two-phase flow model. The source term applied to the wave-damping region; Effective dynamic viscosity; Kinematic viscosity, For turbulent eddy viscosity, Solving using a turbulence model.

[0012] Furthermore, the VOF method with artificial compression technology is used to capture the evolution of the free interface: Its transport equation is defined as: (6) in: Volume fraction represents the percentage of volume occupied by the liquid portion within a single mesh cell. Therefore... The value is between 0 and 1: (7) Based on volume fraction ,density and dynamic viscosity They are defined as follows: (8) Where: subscript l and g They represent liquid and gas, respectively. In the transport equation, the first two terms on the left-hand side constitute the traditional VOF transport equation; the third term is the compressibility term considering the free interface; since The third item only works on the free interface; It is the velocity field used to compress the interface, obtained from the velocity flux on the interface: (9) Where: subscript f For storage on the grid cell surface; It is the direction vector of the mesh cell surface. The modulus is equal to the area of ​​the mesh cell face; It is the velocity flux, which includes the grid movement velocity, and is obtained through the PISO algorithm; This is the free surface compressibility coefficient; the larger the value, the more pronounced the compression effect on the free surface. It is the element normal vector on the free interface, and its definition is as follows: (10) In the formula Stability factor: (11) In the formula N The number of all grid cells; The surface tension term is defined as: (12) In the formula Represents surface tension. Let be the curvature of the free liquid surface, defined as follows: (13) In the formula The volume of each unit; This represents summing the values ​​on all faces of a unit.

[0013] Furthermore, the finite volume method is employed to solve the partial differential equations. This method first requires discretizing the solution domain and dividing it into finite-sized discrete mesh elements. Around each mesh node, a corresponding control volume is constructed in a specific manner: (14) Convert the volume fractions of the second term on the left-hand side and the first term on the right-hand side of the equation into area fractions on the control volume surface: (15) Using the above equation, equation (14) can be expressed as: (16) In the formula, It is due to the convective flow that the normal direction outside the control volume surface is; It is along Flow rate in the direction; express The diffusion rate of the external control variable, where the first term on the left-hand side of the equation represents the control variable. Middle characteristic variables The total amount changes over time.

[0014] A CFD-based aero-hydrodynamic decoupling and collaborative solution system for seaplanes, the system employing the aforementioned CFD-based aero-hydrodynamic decoupling and collaborative solution method for seaplanes, the system comprising: Single-phase flow solver: captures the unsteady aerodynamic response of the wings and fuselage of a seaplane while gliding on water, and uses it to solve for aerodynamic forces; Two-phase flow solver: used to analyze the nonlinear hydrodynamic behavior of seaplane fuselage in waves; Decoupling Coordinator: The single-phase flow solver based on aerodynamics and the two-phase flow solver based on hydrodynamics are decoupled and coordinated to solve the problem at different time steps, so as to accurately simulate the force characteristics and motion response of seaplanes under wave conditions.

[0015] A synchronous coupling and high-fidelity simulation method for aerodynamic and hydrodynamic effects under unsteady conditions is disclosed. The synchronous coupling and high-fidelity simulation method employs a CFD-based decoupling and collaborative solution method for seaplane aerodynamics and hydrodynamics, as described above. The asynchronous coupling and high-fidelity simulation method specifically comprises: During the simulation initialization phase, client / server connections or peer-to-peer bidirectional connections based on the Transmission Control Protocol (TCP) are established for the hydrodynamic solver and the pneumatic solver, respectively. Once the two processes successfully establish a long connection through the specified IP and port, the system enters the asynchronous communication phase. At each time step During the iteration process, data exchange follows a preset send / receive handshake mechanism, and the hydrodynamic solver and the pneumatic solver work together in an asynchronous parallel manner to advance the calculation; among them, the pneumatic solver is dominated by small time steps, while the hydrodynamic solver performs response calculations in large time steps; The specific process is as follows: At any given time step, the hydrodynamic solver first calculates the wave loads and solves the equations of motion. Then, the obtained motion data is interpolated at each small time step in the aerodynamic process and transmitted to the aerodynamic solver, until the aerodynamic solver completes the calculation based on the small time steps. arrive The calculation involves multiple iterative steps. Subsequently, the aerodynamic solver packages the aerodynamic loads according to a predefined data frame structure and sends them to the hydrodynamic solver via a TCP channel. After receiving the data packet, the hydrodynamic solver performs an integrity check. If the check passes, the hydrodynamic solver returns an acknowledgment response to the pneumatic solver and superimposes the wave load with the received aerodynamic load to further solve the motion equations. After the motion equations are solved, the hydrodynamic solver packages the displacement data according to a predefined data frame structure and sends it to the pneumatic solver via a TCP channel. After receiving and verifying the data, the aerodynamic solver updates the boundary conditions and continues to solve the aerodynamic load based on small time steps. Subsequently, the two solvers repeat the above information exchange process until the entire calculation converges or ends.

[0016] Furthermore, the specific working process of the Transmission Control Protocol (TCP) is as follows: First handshake (FIN): The initiating party sends a FIN packet to indicate that no more data needs to be sent; Second handshake ACK: After receiving FIN, the passive party returns ACK to indicate that it has received the disconnect request; The third handshake (FIN): The passive party sends a FIN to indicate that data transmission is complete and the connection is about to be closed; Fourth handshake ACK: After receiving FIN, the initiating party returns ACK, and the connection between the two parties is broken.

[0017] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method described above.

[0018] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the method described above.

[0019] The beneficial effects of this invention are: This invention independently solves for the aerodynamic and hydrodynamic forces acting on a seaplane, and achieves efficient coupling and information exchange between the two during the calculation process through TCP communication technology. This method aims to accurately simulate the comprehensive force characteristics and motion response of a seaplane in a wave environment, providing a more reliable tool for design optimization and safety assessment.

[0020] This invention utilizes TCP communication technology to realize a simulation system for real-time interaction between air and water dynamics, which is used to accurately simulate the force characteristics and motion response of seaplanes under wave conditions, thereby providing a reliable basis for seaplane design, stability assessment and airworthiness analysis. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of the method of the present invention.

[0022] Figure 2 This is a simplified schematic diagram of the computational model of the present invention.

[0023] Figure 3(a) Schematic diagram of the computational domain for aerodynamic single-phase flow.

[0024] Figure 3(b) Schematic diagram of the computational domain for hydrodynamic two-phase flow.

[0025] Figure 4(a) Schematic diagram of aerodynamic computational grid.

[0026] Figure 4(b) Schematic diagram of hydrodynamic computational grid. Detailed Implementation

[0027] 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.

[0028] 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 collections thereof.

[0029] 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.

[0030] The following is in conjunction with the appendix to this application specification. Figure 1 -4. The technical solutions in the embodiments of this application are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in 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.

[0031] 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.

[0032] Implementation Method 1 This embodiment provides a CFD-based method for decoupling and co-solving the aero-hydrodynamics of seaplanes, such as... Figure 1 As shown, the method includes capturing the unsteady aerodynamic response of the wing and fuselage of a seaplane while gliding on water, and using a single-phase flow solver to solve the aerodynamic forces. A two-phase flow solver was used to analyze the nonlinear hydrodynamic behavior of the seaplane fuselage in waves. A decoupled and collaborative solution is achieved by using a single-phase flow solver based on aerodynamics and a two-phase flow solver based on hydrodynamics iteratively at different time steps to accurately simulate the force characteristics and motion response of a seaplane under wave conditions.

[0033] Furthermore, the governing equations of the single-phase flow solver are as follows: (1) (2) (3) in: For velocity field; For pressure; The density of the gas; This is the vector of gravitational acceleration; For temperature.

[0034] The governing equations of the two-phase flow solver are as follows: (4) (5) in: It is the fluid dynamic pressure; The density of a liquid or gas; It is the acceleration due to gravity; For velocity field; This refers to the grid movement speed; This refers to the surface tension term in a two-phase flow model. The source term applied to the wave-damping region; Effective dynamic viscosity; Kinematic viscosity, For turbulent eddy viscosity, Solving using a turbulence model.

[0035] The VOF method with artificial compression technology is used to capture the evolution of free interfaces.

[0036] Its transport equation is defined as: (6) in: Volume fraction represents the percentage of volume occupied by the liquid portion within a single mesh cell. Therefore... The value is between 0 and 1: (7) Based on volume fraction ,density and dynamic viscosity They are defined as follows: (8) Where: subscript l and g They represent liquid and gas, respectively. In the transport equation, the first two terms on the left-hand side constitute the traditional VOF transport equation; the third term is the compressibility term considering the free interface; since The third item only works on the free interface; It is the velocity field used to compress the interface, and its value is obtained from the velocity flux on the interface: (9) Where: subscript f For storage on the grid cell surface; It is the direction vector of the mesh cell surface. The modulus is equal to the area of ​​the mesh cell face; It is the velocity flux, which includes the grid movement velocity, and is obtained through the PISO algorithm; This is the free surface compressibility coefficient; the larger the value, the more pronounced the compression effect on the free surface. It is the element normal vector on the free interface, and its definition is as follows: (10) In the formula Stability factor: (11) In the formula N The number of all grid cells; The surface tension term is defined as: (12) In the formula Represents surface tension. Let be the curvature of the free liquid surface, defined as follows: (13) In the formula The volume of each unit; This represents summing the values ​​on all faces of a unit.

[0037] The finite volume method is employed to solve partial differential equations. This method first discretizes the solution domain into finite-sized discrete mesh elements. Around each mesh node, a corresponding control volume is constructed in a specific manner. The core of this method lies in integrating the governing differential equations into the control volume, thereby achieving a numerical solution.

[0038] (14) Convert the volume fractions of the second term (convection term) on the left-hand side of the equation and the first term (diffusion term) on the right-hand side of the equation into area fractions on the control volume surface: (15) Using the above equation, equation (14) can be expressed as: (16) In the formula, It is due to the convective flow that the normal direction outside the control volume surface is; It is along Flow rate in the direction; express The diffusion rate of the external control variable, where the first term on the left-hand side of the equation represents the control variable. Middle characteristic variables The total amount changes over time.

[0039] Compared to traditional single-solution methods, this method can significantly improve computational accuracy and engineering applicability. The flowchart of this method is as follows: Figure 1 As shown.

[0040] In this invention, the overall model of the seaplane is artificially divided into an aerodynamic part and a hydrodynamic part during the modeling stage. Figure 2 As shown in Figures 3(a) and 3(b), the aerodynamic computational domain is decomposed into two geometrically closed structures (upper and lower) using modeling software, and each structure is exported as an independent STL geometric file. This approach allows the aerodynamic computational domain to be solved based on the upper model, while the hydrodynamic computational domain relies on the lower model for simulation. This enables targeted numerical calculations using single-phase flow solvers and two-phase flow solvers respectively, achieving separate modeling and coupled analysis of aerodynamic and hydrodynamic effects. The computational domains of the single-phase flow solver and the two-phase flow solver are shown in Figures 3(a) and 3(b). The aerodynamic single-phase flow computational domain is 30 meters long, 24 meters wide, and 24 meters high, while the hydrodynamic two-phase flow computational domain is 16 meters long, 16 meters wide, and 7 meters high. As can be seen from the figures, the scale of the aerodynamic computational domain is much larger than that of the hydrodynamic computational domain. Since the hydrodynamic calculation involves a free surface, high-density meshing must be used in local areas to accurately capture the characteristics of the free surface (as shown in Figures 4(a) and 4(b)), which will significantly increase the overall computational load.

[0041] Implementation Method 2 This embodiment provides a CFD-based air-water dynamics decoupling and collaborative solution system for seaplanes. The system uses the CFD-based air-water dynamics decoupling and collaborative solution method for seaplanes as described in Embodiment 1. The system includes: Single-phase flow solver: captures the unsteady aerodynamic response of the wings and fuselage of a seaplane while gliding on water, and uses it to solve for aerodynamic forces; Two-phase flow solver: used to analyze the nonlinear hydrodynamic behavior of seaplane fuselage in waves; Decoupling Coordinator: The single-phase flow solver based on aerodynamics and the two-phase flow solver based on hydrodynamics are decoupled and coordinated to solve the problem at different time steps, so as to accurately simulate the force characteristics and motion response of seaplanes under wave conditions.

[0042] Implementation Method 3 This embodiment provides a method for synchronous coupling and high-fidelity simulation of aerodynamic and hydrodynamic effects under unsteady conditions. The synchronous coupling and high-fidelity simulation method uses a CFD-based decoupling and co-solution method for seaplane aero-hydrodynamics as described in Embodiment 1. TCP (Transmission Control Protocol) is a connection-oriented, reliable transport layer protocol. It establishes a connection through a three-way handshake, uses sequence numbers and acknowledgment mechanisms to ensure reliable data transmission, and supports flow control and congestion control. TCP communication requires establishing a reliable connection between the communicating parties. A three-way handshake is necessary before data transmission, and a four-way handshake terminates the connection at the end of transmission. TCP ensures data reliability through the following mechanisms: Acknowledgment (ACK), where the receiver sends an acknowledgment after each received data transmission; retransmission of data if the sender does not receive an ACK; ordered packet numbering, allowing the receiver to reassemble data in order; and data verification, ensuring data is not corrupted during transmission. TCP uses a sliding window protocol, adjusting the sender's transmission speed according to the receiver's receiving capacity to prevent buffer overflow caused by excessive sending speed. It also adjusts the data transmission speed by detecting network conditions to avoid network congestion. Common algorithms include slow start, congestion avoidance, fast retransmission, and fast recovery.

[0043] The three-way handshake is used to ensure the reliability of the connection established between the two parties, ensuring that they can send and receive data. First handshake (SYN): The client sends a SYN packet (synchronization sequence number) to request the establishment of a connection; and sets the initial sequence number (SEQ).

[0044] The second handshake (SYN-ACK): After receiving the SYN, the server sends a SYN+ACK message to indicate acceptance of the request, along with its own initial sequence number.

[0045] The third handshake (ACK): After receiving SYN+ACK, the client sends an ACK packet to confirm the connection establishment.

[0046] At this point, both parties enter the `ESTABLISHED` state, and the connection is officially established.

[0047] Data transmission: Data segmentation: The data is divided into multiple TCP segments, each with a sequence number and a checksum.

[0048] Data transmission and acknowledgment: After receiving a message, the receiver sends an ACK to acknowledge the received data segment; if the sender does not receive an ACK within the timeout period, it will retransmit the data.

[0049] Flow control: A sliding window protocol is used to dynamically adjust the size of the sending window to ensure that the receiver is not overwhelmed by data.

[0050] Four-way handshake is used for reliable connection disconnection: First handshake (FIN): The initiating party sends a FIN packet to indicate that there is no more data to send.

[0051] Second handshake (ACK): After receiving FIN, the passive party returns ACK to indicate that it has received the disconnect request.

[0052] The third handshake (FIN): The passive party sends FIN to indicate that data transmission is complete and it is ready to disconnect.

[0053] Fourth handshake (ACK): After receiving FIN, the initiating party returns ACK, and the connection between the two parties is broken.

[0054] To achieve tight coupling between the aerodynamic and hydrodynamic solvers, this study constructs a bidirectional data interaction framework based on the TCP communication mechanism. In this framework, a single-phase flow solver is used for aerodynamic calculations, outputting the aerodynamic loads on the fuselage surface at each time step and transmitting them in real-time to the two-phase flow solver via TCP communication. Subsequently, the two-phase flow solver solves for the wave loads on the fuselage considering the free surface effect, and then superimposes these wave loads with the aerodynamic loads to construct a complete external load input, thereby driving the numerical solution of the motion equations. The obtained displacements are fed back to the single-phase flow solver via the same communication mechanism, enabling dynamic updates of the fuselage attitude in the aerodynamic calculations. This process is iterative at each time step, ensuring synchronous coupling and high-fidelity simulation of aerodynamic and hydrodynamic effects under unsteady conditions.

[0055] The synchronous coupling and high-fidelity simulation method specifically includes a simulation initialization phase, a communication phase, and the calculation of the next time step.

[0056] During the simulation initialization phase, client / server connections or peer-to-peer bidirectional connections based on the Transmission Control Protocol (TCP) are established for the hydrodynamic solver and the pneumatic solver, respectively; once the two processes successfully establish a long connection through the specified IP and port, the system enters the asynchronous communication phase. At each time step During the iteration process, data exchange follows a pre-defined send / receive handshake mechanism, and the hydrodynamic solver and the pneumatic solver work together in an asynchronous parallel manner. The pneumatic solver primarily uses small time steps, while the hydrodynamic solver performs response calculations in large time steps.

[0057] The specific process is as follows: At any given time step, the hydrodynamic solver first calculates the wave loads and solves the equations of motion. Then, the obtained motion data is interpolated at each small time step in the aerodynamic process and transmitted to the aerodynamic solver, until the aerodynamic solver completes the calculation based on the small time steps. arrive The calculation involves multiple iterative steps. Subsequently, the aerodynamic solver packages the aerodynamic loads according to a predefined data frame structure and sends them to the hydrodynamic solver via a TCP channel.

[0058] After receiving the data packet, the hydrodynamic solver performs an integrity check. If the check passes, the hydrodynamic solver sends an acknowledgment response to the pneumatic solver and superimposes the wave load with the received aerodynamic load to further solve the equations of motion. Once the equations of motion are solved, the hydrodynamic solver packages the displacement data according to a predefined data frame structure and sends it to the pneumatic solver via a TCP channel.

[0059] After receiving and verifying the data, the aerodynamic solver updates the boundary conditions and continues to solve for the aerodynamic loads based on small time steps. Subsequently, the two solvers repeat the above information exchange process until the entire calculation converges or ends.

[0060] Through the above mechanism, the consistency and real-time performance of data transmission between pneumatic and hydrodynamic solvers can be guaranteed, thereby achieving high-fidelity coupled computation across solvers.

[0061] TCP communication can be implemented in various programming languages. Here, we'll use C++ as an example. Implementing TCP communication in C++ primarily relies on the Socket programming interface provided by the operating system. Commonly used header files include...<sys / socket.h> ,<netinet / in.h> ,<arpa / inet.h> ,<unistd.h> These mechanisms provide basic functionalities for socket creation, address management, data transmission, and connection closure. A typical programming flow is as follows: both the client and server create sockets using `socket()`. The server calls `bind()` and `listen()` to bind the socket to a specified port and enter a listening state, then uses `accept()` to wait for client connections. The client uses `connect()` to initiate a connection to the server. After the connection is established, both sides can perform bidirectional data transmission using `send()` and `recv()`, and finally release resources using `close()`. This mechanism supports stable connection-oriented communication and is a crucial foundation for building distributed simulation solvers with coupled, real-time data exchange capabilities.

[0062] Implementation Method 4 This invention provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor. The memory stores software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and processor are connected via a bus. Specifically, the processor implements any step in Embodiment 1 by running the computer program stored in the memory.

[0063] It should be understood that, in the embodiments of the present invention, the processor may be a Central Processing Unit (CPU), but it may also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0064] Memory may include read-only memory, flash memory, and random access memory, and provides instructions and data to the processor. Some or all of the memory may also include non-volatile random access memory.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A CFD-based method for decoupling and co-solving the aero-hydrodynamics of seaplanes, characterized in that, The method includes: A single-phase flow solver is used to solve the aerodynamic forces, capturing the unsteady aerodynamic response of the wing and fuselage of a seaplane during gliding on water; A two-phase flow solver was used to analyze the nonlinear hydrodynamic behavior of the seaplane fuselage in waves. A decoupled, collaborative solution is achieved by iterating between a single-phase flow solver based on aerodynamics and a two-phase flow solver based on hydrodynamics at different time steps, thus enabling accurate simulation of the force characteristics and motion response of seaplanes under wave conditions.

2. The method according to claim 1, characterized in that, The governing equations of the single-phase flow solver are as follows: (1) (2) (3) in: For velocity field; For pressure; The density of the gas; This is the vector of gravitational acceleration; For temperature.

3. The method according to claim 1, characterized in that, The governing equations of the two-phase flow solver are as follows: (4) (5) in: It is the fluid dynamic pressure; The density of a liquid or gas; It is the acceleration due to gravity; For velocity field; This refers to the grid movement speed; This refers to the surface tension term in a two-phase flow model. The source term applied to the wave-damping region; Effective dynamic viscosity; Kinematic viscosity, For turbulent eddy viscosity, Solved using a turbulence model.

4. The method according to claim 1, characterized in that, The VOF method with artificial compression technology is used to capture the evolution of free interfaces: Its transport equation is defined as: (6) in: Volume fraction represents the percentage of volume occupied by the liquid portion within a single mesh cell. Therefore... The value is between 0 and 1: (7) Based on volume fraction ,density and dynamic viscosity They are defined as follows: (8) Where: subscript l and g They represent liquid and gas, respectively. In the transport equation, the first two terms on the left-hand side constitute the traditional VOF transport equation; the third term is the compressibility term considering the free interface; since The third item only works on the free interface; It is the velocity field used to compress the interface, obtained from the velocity flux on the interface: (9) Where: subscript f For storage on the grid cell surface; It is the direction vector of the mesh cell surface. The modulus is equal to the area of ​​the mesh cell surface; It is the velocity flux, which includes the grid movement velocity, and is obtained through the PISO algorithm; This is the free surface compressibility coefficient; the larger the value, the more pronounced the compression effect on the free surface. It is the element normal vector on the free interface, and its definition is as follows: (10) In the formula Stability factor: (11) In the formula N The number of all grids; The surface tension term is defined as: (12) In the formula Represents surface tension. Let be the curvature of the free liquid surface, defined as follows: (13) In the formula The volume of each unit; This represents summing the values ​​on all faces of a unit.

5. The method according to claim 1, characterized in that, The finite volume method is used to solve partial differential equations. This method first requires discretizing the solution domain and dividing it into finite-sized discrete mesh elements. Around each mesh node, a corresponding control volume is constructed in a specific manner. (14) Convert the volume fractions of the second term on the left-hand side and the first term on the right-hand side of the equation into area fractions on the control volume surface: (15) Based on the above formula, equation (14) can be expressed as: (16) In the formula, It is due to the convective flow that the normal direction outside the control volume surface is; It is along Flow rate in the direction; express The diffusion rate of the external control variable, where the first term on the left-hand side of the equation represents the control variable. Middle characteristic variables The total amount changes over time.

6. A decoupled and collaborative solution system for the aero-hydrodynamics of a seaplane based on the CFD method, characterized in that, The system uses a CFD-based decoupling and collaborative solution method for the aero-hydraulic dynamics of seaplanes as described in any one of claims 1-5. The system includes: Single-phase flow solver: captures the unsteady aerodynamic response of the wings and fuselage of a seaplane while gliding on water, and uses it to solve for aerodynamic forces; Two-phase flow solver: used to analyze the nonlinear hydrodynamic behavior of seaplane fuselage in waves; Decoupling Coordinator: Based on the aerodynamic single-phase flow solver and the hydrodynamic two-phase flow solver, decoupling and coordinating the solution at different time steps to achieve accurate simulation of the force characteristics and motion response of seaplanes under wave conditions.

7. A method for asynchronous coupling and high-fidelity simulation of aerodynamic and hydrodynamic effects under unsteady conditions, characterized in that, The synchronous coupling and high-fidelity simulation method uses a CFD-based decoupling and collaborative solution method for the aero-hydraulic dynamics of seaplanes as described in any one of claims 1-5. Specifically, the asynchronous coupling and high-fidelity simulation method is as follows: During the simulation initialization phase, client / server connections or peer-to-peer bidirectional connections based on the Transmission Control Protocol (TCP) are established for the hydrodynamic solver and the pneumatic solver, respectively. Once the two processes successfully establish a long connection through the specified IP and port, the system enters the asynchronous communication phase. At each time step During the iteration process, data exchange follows a preset send / receive handshake mechanism, and the hydrodynamic solver and the pneumatic solver work together in an asynchronous parallel manner to advance the calculation; among them, the pneumatic solver is dominated by small time steps, while the hydrodynamic solver performs response calculations in large time steps; The specific process is as follows: At any given time step, the hydrodynamic solver first calculates the wave loads and solves the equations of motion; then, it interpolates the obtained motion data at each small time step in the aerodynamic process and transmits it to the aerodynamic solver, until the aerodynamic solver completes the calculation based on the small time steps. arrive The multi-step iterative calculation is performed; subsequently, the aerodynamic solver packages the aerodynamic loads according to a predefined data frame structure and sends them to the hydrodynamic solver via a TCP channel. After receiving the data packet, the hydrodynamic solver performs an integrity check. If the check passes, the hydrodynamic solver returns an acknowledgment response to the pneumatic solver and superimposes the wave load with the received aerodynamic load to further solve the motion equations. After the motion equations are solved, the hydrodynamic solver packages the displacement data according to a predefined data frame structure and sends it to the pneumatic solver via a TCP channel. After receiving and verifying the data, the aerodynamic solver updates the boundary conditions and continues to solve the aerodynamic load based on small time steps. Subsequently, the two solvers repeat the above information exchange process until the entire calculation converges or ends.

8. The asynchronous coupling and high-fidelity simulation method for aerodynamic and hydrodynamic effects under unsteady conditions according to claim 7, characterized in that, The specific working process of the Transmission Control Protocol (TCP) is as follows: First handshake (FIN): The initiating party sends a FIN packet to indicate that no more data needs to be sent; Second handshake ACK: After receiving FIN, the passive party returns ACK to indicate that it has received the disconnect request; The third handshake (FIN): The passive party sends a FIN to indicate that data transmission is complete and the connection is about to be closed; Fourth handshake ACK: After receiving FIN, the initiating party returns ACK, and the connection between the two parties is broken.

9. A computer device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, it implements the method as described in any one of claims 1-6.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method as described in any one of claims 1-6.

Images