Aerodynamics calculation method and system based on non-structural-Cartesian hybrid grid

Abstract

The invention discloses an aerodynamic calculation method and system based on a non-structural-Cartesian hybrid grid, and belongs to the technical field of fluid mechanics numerical simulation. By receiving and analyzing various input files, generating a hybrid grid, initializing a flow field and combining various calculation methods for solving, a Cartesian grid can be dynamically adjusted according to speed divergence and rotation criteria in the flow field, and finally a calculation result including pressure change at a pressure monitoring point is output. The hybrid grid provided by the invention gives consideration to both complex geometric adaptability and calculation efficiency, various calculation methods meet different requirements, dynamic monitoring and parameter adjustment improve the calculation precision, and the limitation of a traditional method in the aspects of complex geometric shape processing, turbulence simulation and the like can be effectively solved; and high-precision and high-efficiency aerodynamics simulation support is provided for industries such as aerospace, automobiles and buildings.

Description

Technical Field

[0001] The present invention relates to the technical field of numerical simulation of fluid mechanics, and more specifically, to an aerodynamic calculation method and system based on an unstructured-Cartesian hybrid grid. Background Art

[0002] In modern industrial design and research, the accurate prediction of aerodynamic performance is crucial for industries such as aerospace, automotive, and architecture.

[0003] Traditional aerodynamic calculation methods face many challenges when dealing with complex geometries. For example, structured grids are difficult to precisely fit at complex boundaries, resulting in a decrease in calculation accuracy; while unstructured grids can better adapt to complex geometries, but the calculation efficiency is relatively low. In addition, some existing calculation methods also have certain limitations in turbulence simulation, time marching, etc., and cannot meet various calculation requirements. Especially in scenarios where high-precision simulation and efficient calculation are required simultaneously, these problems are more prominent.

[0004] Therefore, how to propose an aerodynamic calculation method and system based on an unstructured-Cartesian hybrid grid to achieve high-precision and efficient simulation of aerodynamic problems under complex geometric conditions is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides an aerodynamic calculation method and system based on an unstructured-Cartesian hybrid grid to meet various calculation requirements.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention proposes an aerodynamic calculation method based on an unstructured-Cartesian hybrid grid, including the following steps:

[0008] Receiving and parsing various input files; the input files include a flow field calculation configuration file, an unstructured grid file in Gmsh format, a Cartesian grid related configuration file, and a pressure monitoring point coordinate input file;

[0009] Generating an unstructured-Cartesian hybrid grid according to the input files, realizing hybrid grid calculation, and initializing the flow field;

[0010] Based on the unstructured-Cartesian hybrid grid, combining various calculation methods to calculate aerodynamic problems, and dynamically adjusting the Cartesian grid according to the flow field situation during the calculation process;

[0011] Real-time output of various data, and outputting the flow field and wall calculation results according to the set output interval steps.

[0012] Preferably, a non-structured Cartesian hybrid grid is generated according to the input file to implement hybrid grid calculation, including:

[0013] Construct a Cartesian background grid according to the geometric feature parameters in the Cartesian grid related configuration file;

[0014] Let the non-structured grid establish the grid relationship with the Cartesian background grid through the contribution cell method, specifically, to achieve the transfer of hybrid grid information.

[0015] Preferably, configure the various calculation methods through the flow field calculation configuration file, including: gradient reconstruction, flux calculation, steady-state time advancement, unsteady time advancement, turbulence model, limiter.

[0016] Preferably, output various data in real time, and output the flow field and wall calculation results according to the set output interval steps, including:

[0017] According to the pressure monitoring point coordinate input file, dynamically monitor and record the pressure calculation results of each monitoring point.

[0018] On the other hand, the present invention also discloses an aerodynamic calculation system based on a non-structured Cartesian hybrid grid for implementing the above aerodynamic calculation method, including:

[0019] An input module for receiving and parsing various input files; the input files include a flow field calculation configuration file, a non-structured grid file in Gmsh format, a Cartesian grid related configuration file, and a pressure monitoring point coordinate input file;

[0020] A grid processing module for generating a non-structured Cartesian hybrid grid according to the input file to implement hybrid grid calculation, initializing the flow field, and also for dynamically adjusting the Cartesian grid according to the flow field situation;

[0021] A calculation and analysis module for calculating aerodynamic problems based on the non-structured Cartesian hybrid grid and combining various calculation methods;

[0022] An output module for outputting various data in real time and outputting the flow field and wall calculation results according to the set output interval steps.

[0023] Preferably, the output module includes:

[0024] A pressure monitoring unit for monitoring and recording the pressure calculation results of each monitoring point in real time according to the pressure monitoring point coordinate input file.

[0025] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses an aerodynamic calculation method and system based on unstructured-Cartesian hybrid grids. By receiving and parsing various input files, generating hybrid grids and initializing the flow field, combining various calculation methods for solution, dynamically adjusting grid calculations based on the velocity divergence and curl data in the flow field, and finally outputting the calculation results. The hybrid grids proposed by the present invention take into account both complex geometry adaptability and calculation efficiency. The various calculation methods meet different requirements, and the adaptability of Cartesian grids improves the calculation accuracy, which can effectively solve the limitations of traditional methods in dealing with complex geometric shapes, turbulence simulations, etc., and provide high-precision and efficient aerodynamic simulation support for industries such as aerospace, automotive, and architecture. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0027] Figure 1 It is a flowchart of the method provided by the present invention;

[0028] Figure 2 It is a system architecture diagram provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0030] On the one hand, an embodiment of the present invention discloses an aerodynamic calculation method based on unstructured-Cartesian hybrid grids, as Figure 1 shown, including the following steps:

[0031] S1. Receive and parse various types of input files; the input files include a flow field calculation configuration file, an unstructured grid file in Gmsh format, a Cartesian grid related configuration file, and a pressure monitoring point coordinate input file.

[0032] Using a dedicated file parsing program, read and parse various input files according to the predefined file format specifications. For the flow field calculation configuration file, parse parameters such as the type of governing equations set therein (Euler equations, Navier-Stokes equations, RANS-SA coupling equations, etc.), the selected gradient reconstruction method (Green-Gauss reconstruction or Least-Square reconstruction), the flux calculation method (linear reconstruction / U-MUSCL reconstruction combined with Roe / HLLC Riemann solver), etc., and read calculation condition-related parameters such as boundary conditions and flow field initialization; for the unstructured grid file in Gmsh format, extract information such as grid node coordinates, element connection relationships, boundary surface link relationships, and boundary surface types; the Cartesian grid-related configuration file is used to obtain parameters such as the maximum refinement level, coverage range, and initial grid division of the Cartesian grid; the pressure monitoring point coordinate input file reads the coordinate information of the monitoring points for which the pressure evolution data needs to be monitored.

[0033] Meanwhile, ensure that the operating computer has the corresponding hardware resources and software environment, and install and configure the Fortran compiler.

[0034] S2. Generate an unstructured-Cartesian hybrid grid based on the input files, perform hybrid grid calculations, and initialize the flow field.

[0035] Based on the geometric feature parameters in the Cartesian grid-related configuration file, determine the grid spacing, number of layers, etc. of the Cartesian grid. Adopt a parametric modeling method to automatically adjust the layout of the Cartesian grid according to the geometric shape of the computational domain.

[0036] When fusing the unstructured grid and the Cartesian background grid, search for the contributing elements corresponding to the overlapping boundary faces of the other set of grids in the unstructured grid and the Cartesian background grid respectively, establish the grid relationship through the contributing element method, and realize the transfer of hybrid grid information to ensure the accurate transfer of flow field information between different grid types.

[0037] Initialize the flow field according to the selected governing equations and calculation conditions, and set the initial values of each physical quantity in the flow field. For inviscid flow and laminar flow calculations, calculate physical quantities such as density and velocity based on the initialization parameters, and then calculate the initial values of the conserved variables of the continuity equation, momentum equation, and energy equation therefrom; for turbulent flow calculations, in addition to the basic physical quantities, corresponding turbulent parameters (such as turbulent kinetic energy, etc.) also need to be initialized according to the selected turbulent model (such as SA, SA-DES, k-ω, k-ωSST, SST-DES, etc.).

[0038] S3. Based on the unstructured-Cartesian hybrid grid, a variety of calculation methods are combined to calculate aerodynamic problems. Various calculation methods are configured through the flow field calculation configuration file, including: gradient reconstruction, flux calculation, steady time advancement, unsteady time advancement, turbulence model, and limiter.

[0039] During the solution process, iterative calculations are performed according to the selected steady time advancement algorithm (third-order Runge-Kutta, LU-SGS, DPLUR, GMERS) or unsteady time advancement algorithm (third-order Runge-Kutta or dual time step method). In each iteration, the gradient of the flow field variables in the grid unit is first calculated using the selected gradient reconstruction method, and then the flux on the grid unit surface is obtained by the flux calculation method, so as to advance the time and update the flow field variables. During the calculation process, the turbulent viscosity term is calculated according to the selected turbulence model, and the influence of turbulence on the flow is considered. At the same time, the venk limiter is used to limit the gradient of the conserved variables in the calculation process to prevent numerical oscillation.

[0040] During the calculation process, according to the input settings, the Cartesian grid can be adaptively adjusted based on the velocity divergence and velocity curl data of the flow field, and the grid density of some areas can be modified.

[0041] S4. Output various data in real time, and output the flow field and wall calculation results according to the set output interval steps.

[0042] After the calculation is completed, the flow field data is output, including the distribution of physical quantities such as velocity, pressure, temperature, etc. in the entire calculation domain; aerodynamic information such as lift coefficient, drag coefficient, moment coefficient, etc. are output; and a continuation file is also output, containing all necessary information on the current calculation status for subsequent calculations.

[0043] In this embodiment, according to the pressure monitoring point coordinate input file, the pressure change of the monitoring point over time is monitored and recorded until the calculation is completed.

[0044] Specifically, the grid parameter adjustment strategy of this embodiment is as follows:

[0045] When the flow field in a certain area is monitored to change dramatically, such as a large velocity divergence or curl, the system will automatically locally encrypt the grid in that area;

[0046] By analyzing the velocity divergence and curl data of each unit and comparing the average flow field data, we can determine whether the density distribution of the grid in the entire calculation domain is reasonable. If it is found that the grid in some areas is too sparse, resulting in inaccurate calculation results, and the grid in other areas is too dense, resulting in a waste of computing resources, the density of the grid is optimized as a whole.

[0047] The algorithm parameter adjustment strategy is as follows:

[0048] If it is found that the convergence rate is too slow or divergence occurs during the calculation process, it is necessary to adjust the time marching algorithm or modify the CFL number. In steady-state calculations, if the third-order Runge-Kutta algorithm does not achieve good convergence, try switching to the LU-SGS or DPLUR algorithm to improve the convergence rate and stability.

[0049] After adjusting the grid and algorithm parameters, iterative calculations will be performed again. During each iteration, the pressure changes at the monitoring points will be continuously monitored and recorded in a file. These conditions include the number of calculation steps and residuals, etc. When the order of magnitude of the residuals drops below a certain threshold, the system determines that the calculation results meet the conditions and stops the iterative calculation.

[0050] On the other hand, referring to Figure 2 , the present invention also discloses an aerodynamic calculation system based on an unstructured-Cartesian hybrid grid for implementing the above aerodynamic calculation method, including:

[0051] An input module for receiving and parsing various input files; the input files include a flow field calculation configuration file, an unstructured grid file in Gmsh format, a Cartesian grid related configuration file, and a pressure monitoring point coordinate input file;

[0052] A grid processing module for generating an unstructured-Cartesian hybrid grid according to the input files, realizing information transfer between the hybrid grids, initializing the flow field, and also for dynamically adjusting the Cartesian grid according to the flow field situation;

[0053] A calculation and analysis module for calculating aerodynamic problems based on the unstructured-Cartesian hybrid grid and combining various calculation methods;

[0054] An output module for real-time output of various data, and outputting the flow field and wall calculation results according to the set output interval steps.

[0055] In this embodiment, the output module includes a pressure monitoring unit for real-time monitoring and recording the pressure calculation results of each monitoring point according to the pressure monitoring point coordinate input file.

[0056] Each embodiment in this specification is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0057] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An aerodynamic calculation method based on unstructured-Cartesian hybrid grid, characterized in that: The following steps are involved: Receive and parse various input files; the input files include flow field calculation configuration files, unstructured grid files in Gmsh format, Cartesian grid related configuration files, and pressure monitoring point coordinate input files; generating an unstructured-Cartesian hybrid grid according to the input file, realizing hybrid grid calculation, and initializing a flow field; Based on the unstructured-Cartesian hybrid grid, aerodynamic problems are calculated by combining multiple calculation methods. During the calculation process, the Cartesian grid is dynamically adjusted according to the flow field conditions. Output various data in real time, and output flow field and wall calculation results according to the set output interval steps.

2. The aerodynamic calculation method based on unstructured-Cartesian hybrid grid according to claim 1, characterized in that: Generate an unstructured-Cartesian hybrid grid according to the input file to implement hybrid grid calculation, including: Constructing a Cartesian background grid according to geometric feature parameters in a Cartesian grid-related configuration file; The unstructured grid and the Cartesian background grid are allowed to establish a grid relationship through a contribution unit method to achieve hybrid grid information transmission.

3. The aerodynamic calculation method based on unstructured-Cartesian hybrid grid according to claim 1, characterized in that: The multiple calculation methods are configured through the flow field calculation configuration file, including: gradient reconstruction, flux calculation, steady time advancement, unsteady time advancement, turbulence model, and limiter.

4. The aerodynamic calculation method based on unstructured-Cartesian hybrid grid according to claim 1, characterized in that: Output various data in real time, and output flow field and wall calculation results according to the set output interval steps, including: According to the pressure monitoring point coordinate input file, the pressure calculation results of each monitoring point are dynamically monitored and recorded.

5. An aerodynamic calculation system based on unstructured-Cartesian hybrid grid, characterized in that: include: Input module, used to receive and parse various input files; The input files include flow field calculation configuration files, unstructured grid files in Gmsh format, Cartesian grid related configuration files, and pressure monitoring point coordinate input files; A grid processing module, used to generate an unstructured-Cartesian hybrid grid according to the input file, realize hybrid grid calculation, initialize the flow field, and dynamically adjust the Cartesian grid according to the flow field conditions; The computational analysis module is used to calculate aerodynamic problems based on unstructured-Cartesian hybrid grids and a combination of multiple computational methods; The output module is used to output various data in real time and output the flow field and wall calculation results according to the set output interval steps.

6. The aerodynamic calculation system based on unstructured-Cartesian hybrid grid according to claim 5, characterized in that: The output module comprises: The pressure monitoring unit is used to monitor and record the pressure calculation results of each monitoring point in real time according to the pressure monitoring point coordinate input file.

Images