A dynamic mesh processing method and system for ablating a composite material surface

Abstract

The application discloses a kind of composite material surface ablating dynamic mesh processing method and system, belong to the field of computational mechanics and heat transfer, including steps: S1, model initialization and parameter definition;S2, after determining model and parameter, coupling solving material surface ablation and thermal response;S3, after obtaining material surface ablation and thermal response, based on the element deletion criterion and execution of ablation depth;S4, after element deletion, execute dynamic boundary identification and update;S5, time step advances, repeat step S2 to step S4, until reach the preset total length of simulation.This application can not only accurately simulate the non-steady thermal response inside material, but also clearly and intuitively reproduce the macroscopic geometric shape change caused by ablation, and has superiority in handling complex moving boundary problems.

Description

Technical Field

[0001] This invention relates to the fields of computational mechanics and heat transfer, and more specifically, to a dynamic mesh processing method and system for the ablation retreat of composite material surfaces. Background Technology

[0002] When an aircraft flies at high speed, the heat-resistant materials on its surface undergo intense aerodynamic heating, leading to physical and chemical changes known as ablation. Ablation causes material mass loss and changes in surface morphology (called ablation regression), which significantly affect the material's heat transfer performance and structural integrity.

[0003] In traditional finite element analysis, simulating moving boundary problems typically employs the Arbitrary Lagrange-Euler (ALE) method or the immersed boundary method. The ALE method adapts to boundary changes by moving and reconstructing the mesh, but it is prone to severe mesh distortion when the ablation amount is large, leading to decreased computational accuracy or even non-convergence. While the immersed boundary method can handle complex geometric changes, it is complex to implement and faces difficulties in accurately applying boundary conditions. Another approach is the element birth and death technique, which predefines a mesh containing potentially ablated regions and "kills" elements during computation based on criteria. However, traditional element birth and death techniques usually only multiply the element's stiffness matrix by a very small factor; the element remains in the mesh, increasing unnecessary computational burden. A more direct method is to directly delete elements from the mesh, but this presents new technical challenges.

[0004] 1) Boundary Update: When a surface element is deleted, its neighboring elements become new surface elements. There must be a reliable mechanism to identify these newly exposed surfaces and update them as new surface boundaries in order to correctly apply aerodynamic, thermal, and pressure loads.

[0005] 2) Data consistency: Changes to the mesh topology must be communicated to all relevant computational modules (such as solvers, boundary conditions, material models, etc.) to prevent the use of outdated or invalid mesh information (such as cached element pointers or boundary data), otherwise the program will crash.

[0006] 3) Ablation Criterion: An accurate and efficient criterion is needed to determine which cells should be deleted in the current time step.

[0007] Therefore, existing technologies suffer from problems such as mesh distortion, computational instability, and difficulty in boundary updating when dealing with large-scale ablation retreat. There is an urgent need for a mesh processing scheme that can accurately simulate ablation retreat, dynamically update surface boundaries, and is tightly coupled with the finite element framework. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dynamic mesh processing method and system for the ablation retreat of composite material surfaces, which avoids the problem of mesh distortion and has the advantages of high computational efficiency, high accuracy and simple implementation.

[0009] The objective of this invention is achieved through the following solution:

[0010] A dynamic mesh processing method for ablation retreat of composite material surface includes the following steps:

[0011] S1, Model initialization and parameter definition;

[0012] S2, after determining the model and parameters, couple the solution of material surface ablation and thermal response.

[0013] S3, after obtaining the ablation and thermal response of the material surface, the cell deletion criterion and execution are based on the ablation depth;

[0014] S4, After the cell is deleted, perform dynamic boundary identification and update;

[0015] S5, advance the time step, repeat steps S2 to S4 until the preset total simulation time is reached.

[0016] Furthermore, in step S1, the model initialization specifically establishes an initial finite element mesh model describing the structure to be analyzed, which has an initial geometric shape, size and initial thickness.

[0017] Furthermore, in step S1, the parameter definition specifically determines the environmental parameters and thermal property parameters.

[0018] Furthermore, the environmental parameters include the recovery enthalpy of the flow, the reference cold wall heat flux, the gas pressure, and the gas composition; the thermophysical parameters include density, specific heat, and a function of temperature.

[0019] Furthermore, in step S2, the coupled solution of material surface ablation and thermal response specifically includes the following sub-steps:

[0020] S21, Surface Heat Flow Calculation: Based on the current wall temperature and environmental parameters, the ablation rate of the material surface and the net heat flow generated by convection, radiation, and chemical reactions are calculated by solving the surface chemical reaction equilibrium and energy balance equations. q _net;

[0021] S22, Heat Conduction Analysis: Calculate the net heat flow obtained in step S21... q _net, as a boundary condition, is applied to the current ablation surface of the material to solve the transient heat conduction equation inside the structure and obtain the updated temperature field distribution in the entire structural domain.

[0022] S23, repeat steps S21 and S22 until the temperature and heat flow converge in the current time step, and obtain a stable and consistent temperature field and ablation rate at the current moment.

[0023] Furthermore, in step S21, the ablation rate of the material surface specifically includes the mass loss rate and the line retreat rate.

[0024] Further, in step S3, the cell deletion criterion and execution based on the ablation depth specifically includes the following sub-steps:

[0025] S31, Cumulative ablation depth calculation: based on the current time step Δ t and the maximum ablation rate calculated on the current ablated surface. v _max, updates the total cumulative ablation depth S, calculated as: S_new = S_old + v _max * Δ t S_new represents the current ablation depth, and S_old represents the ablation depth of the previous time step.

[0026] S32, Element Deletion Decision: Traverse each element in the mesh, obtain the geometric center coordinates y_e of that element, and determine the element's existence or deletion based on the following criteria:

[0027] Calculate the remaining thickness of the current material: H_current = H - S_new;

[0028] If y_e exceeds or equals the height of the existing material, satisfying y_e ≥ H_current, then the element should be deleted; otherwise, the element should be retained; H is the initial thickness.

[0029] S33, Element Deletion Execution: Removes the elements that are determined to be deleted from the finite element mesh.

[0030] Furthermore, in step S33, the removal of the specific mesh topology directly modifies the structure, thereby forming a new ablation surface.

[0031] Furthermore, in step S4, the dynamic boundary identification and update process specifically includes the following sub-steps:

[0032] S41, New Boundary Identification: Traverse all neighboring cells of the deleted cell. The inner boundary that was originally adjacent to the deleted cell is now exposed and becomes the new outer boundary.

[0033] S42, Boundary Condition Redirection: Identify and mark these newly exposed boundaries as new “ablation surface” boundaries;

[0034] S43, Notify System Update: Notify all modules of the numerical computation system that the grid topology has changed and to use the updated grid information for the next calculation.

[0035] A dynamic mesh processing system for ablation retreat of composite material surfaces includes a computer device, the computer device including a processor and a memory, the memory storing a computer program that, when loaded by the processor, executes the method described in any of the preceding claims.

[0036] The beneficial effects of this invention include:

[0037] (1) Completely avoid mesh distortion: The method of this invention uses a fixed Eulerian mesh and simulates boundary motion by deleting elements instead of moving nodes, which fundamentally avoids the serious mesh distortion and calculation failure problems encountered by methods such as ALE under large deformations, and greatly enhances the robustness of numerical simulation.

[0038] (2) High computational efficiency: Compared with complex global mesh reconstruction methods, the cell deletion and local boundary update operations of the present invention are simpler, more efficient, and have low computational overhead, making them particularly suitable for simulating long-term, large-scale ablation processes.

[0039] (3) High accuracy and simple implementation: The method of this invention can clearly track the ablation front, and the newly formed ablation surface is precisely composed of the boundary surfaces of a series of elements. The application of boundary conditions directly acts on these new boundaries, ensuring the accuracy of heat flow calculation. The entire algorithm has a clear logic and is easy to implement within the existing finite element framework.

[0040] (4) Strong versatility: The method of the present invention is not only applicable to thermal ablation problems, but can also be extended to other moving boundary problems involving material removal, especially the ablation problem of flat-headed bodies. It has broad application prospects in fields such as electrochemical corrosion and mechanical wear.

[0041] (5) This invention can not only accurately simulate the unsteady thermal response inside the material, but also clearly and intuitively reproduce the changes in macroscopic geometric shape caused by ablation, which is superior in dealing with complex moving boundary problems. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1a The physical model for the physical calculation model of ablation retreat;

[0044] Figure 1b The computational grid for the physical calculation model of ablation retreat;

[0045] Figure 2 This is a flowchart of the ablation retreat calculation based on mesh deletion;

[0046] Figure 3a For the ablation retreat calculation results based on mesh deletion in t = 0s Temperature distribution diagram;

[0047] Figure 3b For the ablation retreat calculation results based on mesh deletion in t = 5s temperature distribution diagram;

[0048] Figure 3c For the ablation retreat calculation results based on mesh deletion in t = Temperature distribution diagram over 10 seconds;

[0049] Figure 3d For the ablation retreat calculation results based on mesh deletion in t = Temperature distribution diagram over 15 seconds;

[0050] Figure 3e For the ablation retreat calculation results based on mesh deletion in t = 20s temperature distribution diagram;

[0051] Figure 3f For the ablation retreat calculation results based on mesh deletion in t = Temperature distribution diagram over 30 seconds. Detailed Implementation

[0052] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0053] The specific implementation process of this invention is as follows:

[0054] To address the problems mentioned in the background, this invention specifically proposes a dynamic mesh processing method for the ablation retreat of composite material surfaces. This method effectively handles the progressive material removal caused by ablation retreat within a coupled multiphysics finite element simulation framework, dynamically updating the computational domain boundaries and maintaining numerical stability during this process. Therefore, this invention aims to solve the following technical challenges encountered by existing numerical simulation methods when dealing with large-scale material ablation problems: 1) Mesh distortion under large deformation: How to avoid mesh distortion and computational failure caused by significant material surface retreat in traditional Lagrangian methods. 2) Balancing computational efficiency and accuracy: How to develop an efficient method that is computationally cost-effective yet accurately captures ablation boundary movement and thermo-structural response. 3) Accurate application of dynamic boundaries: How to accurately apply boundary conditions such as aerodynamic heat flow during the continuous formation of new boundaries due to ablation to ensure the correctness of temperature field calculations.

[0055] In a preferred embodiment, the invention specifically relates to a numerical method for simulating surface ablation and recession of materials under high-temperature conditions in finite element analysis, particularly a technical solution for simulating changes in material surface morphology by dynamically deleting mesh elements. Specifically, the method of this embodiment performs heat conduction analysis on a fixed Eulerian mesh and dynamically deletes elements representing ablated material using a suitable criterion, thereby simulating surface recession of the material.

[0056] Taking a cylindrical heat-resistant structure as an example, a two-dimensional cross-sectional diagram is given here, as follows: Figure 1a and Figure 1b As shown, the dynamic material loss, i.e., the mesh removal process, is analyzed. For example, a carbon-based composite plate with an initial height of 50.5 mm and a width of 16 mm undergoes ablation on its upper surface due to continuous heating by a high-temperature gas flow. The bottom surface of the plate is kept at a constant temperature of 300 K, while the two sides are considered adiabatic. This embodiment aims to simulate the ablation process of this plate over 30 seconds, and the calculation results are as follows. Figures 3a-3f As shown. The method of this embodiment of the invention specifically includes the following steps:

[0057] Step S1: Model initialization and parameter definition

[0058] S11, Establish an initial finite element mesh model describing the structure to be analyzed. This model has an initial geometric shape and dimensions, and an initial thickness H.

[0059] S12, determine environmental parameters, including the recovery enthalpy of the incoming flow, the reference cold wall heat flux, gas pressure, gas composition, etc.

[0060] S13 determines the thermal properties of the material, including density, specific heat, thermal conductivity, etc., as functions of temperature.

[0061] Specifically, a two-dimensional rectangular computational domain representing the plate is first established and discretized into a finite element mesh, for example, divided into 32*101 quadrilateral elements, such as... Figure 1a and Figure 1b As shown. Secondly, a variable is defined in the system to describe the temperature distribution, and its initial value is set to 300K. Simultaneously, an auxiliary physical field variable can be defined to store and transmit the modified or enhanced ablation rate (considering the mechanical erosion effect).

[0062] Physical Model and Parameter Configuration: Environmental Condition Definition: The high-temperature gas flow environment is parameterized and defined as a set of input data, including the gas flow recovery enthalpy, reference cold wall heat flux, gas pressure, etc. The relevant parameter settings are given here, including: recovery enthalpy 8.051e6 J / kg, cold wall heat flux 18.338e6 W / m³. 2 The cold wall heat flux reference wall temperature is 0 K, total pressure is 5.901 atm, oxygen partial pressure is 1.23921 atm, nitrogen partial pressure is 4.66179 atm, and air molar mass is 0.02897 kg / mol. Ablation Physics Model: Defines a calculation module for calculating the ablation of carbon material surfaces. This module calculates the linear ablation rate of the material surface by solving relevant physicochemical equations based on the current surface temperature and external environmental conditions. Surface Energy Flow Model: Defines a calculation module for calculating the net surface heat flow. This module calculates the net heat flux finally applied to the material surface by comprehensively considering various effects such as convection, radiation, and chemical reactions, based on the current surface temperature and intermediate results of ablation calculations (such as catalytic recombination and exothermic chemical reactions). Ablation Enhancement Model: To simulate more complex physical phenomena such as mechanical ablation, a derived data calculation module can be configured. This module obtains the basic linear ablation rate and processes it (e.g., multiplying it by an enhancement factor greater than 1) to obtain an equivalent ablation rate that considers the enhancement effect.

[0063] Boundary condition configuration: A fixed temperature of 300K is applied to the bottom boundary of the model; an adiabatic boundary condition with zero heat flux is applied to the left and right boundaries; and a heat flux boundary condition coupled to the physical model is applied to the top surface of the model (i.e., the top, the initial ablation surface). The value of this boundary condition is not a constant, but dynamically obtained from the calculated net heat flux in the above "surface energy flow model".

[0064] Step S2: Coupled solution of surface ablation and thermal response. The following coupled iterative calculations should be performed within one computation time step:

[0065] S21, Surface Heat Flow Calculation: Based on the current wall temperature and environmental parameters, the ablation rate (mass loss rate and linear regression rate) of the material surface and the net heat flow generated by convection, radiation, and chemical reactions are calculated by solving the surface chemical reaction equilibrium and energy balance equations. q _net.

[0066] S22, Heat Conduction Analysis: Calculate the net heat flow obtained in step S21... q _net is applied as a boundary condition on the current ablation surface of the material to solve the transient heat conduction equation inside the structure and obtain the updated temperature field distribution in the entire structural domain.

[0067] S23. Repeat steps S21 and S22 until the temperature and heat flow converge in the current time step, and obtain a stable and consistent temperature field and ablation rate at the current moment.

[0068] Specifically, based on the current wall temperature and environmental parameters, the ablation rate (mass loss rate and linear regression rate) of the material surface, as well as the net heat flux generated by convection, radiation, and chemical reactions, are calculated by solving the surface chemical reaction equilibrium and energy balance equations. q _net. This will determine the net heat flow. q _net is applied as a boundary condition on the current ablation surface of the material to solve the transient heat conduction equation inside the structure and obtain the updated temperature field distribution in the entire structural domain.

[0069] Transient analysis methods are employed for solving the problem, such as the preprocessed, non-Jacobi (matrix) Newton-Krylov method, with an adaptive time step adjustment mechanism configured to improve efficiency while ensuring computational convergence. A brief introduction to the non-Jacobi (matrix) Newton-Krylov method is given below.

[0070] Newton's method: For a system of nonlinear equations F ( u If ) = 0, the standard Newton's method uses the current solution... u k Linearization is performed in the vicinity to find the next approximate solution. u k+1 :

[0071] (1);

[0072] (2);

[0073] in, The Jacobian matrix represents the function... F For variables uThe first derivative of . Solving this system of linear equations is the key to every step of Newton's method.

[0074] Krylov Subspace Method: When the problem size is very large, directly solve the above linear equation system (i.e., calculate the inverse of the Jacobian matrix). J -1 The computational cost of solving linear equations is very high. Therefore, iterative methods are usually used to approximate the solution. Here, we consider the Krylov subspace method, such as GMRES (Generalized Minimal Residual Method). The core of this type of method is to find an approximate solution to the system of linear equations in a low-dimensional space called a "Krylov subspace", which avoids directly calculating the inverse of the matrix and is more efficient.

[0075] Jacobian-Free: This is the essence of the preprocessed Jacobian-free (matrix) Newton-Kriloff method. In the current ablation problem, the Jacobian matrix... J The form is very complex, and manual derivation and programming implementation are extremely difficult and error-prone. The "no Jacobi" method cleverly bypasses this problem, and its core lies in utilizing a mathematical approximation:

[0076] (3);

[0077] in, It is a vector. It is a small quantity. The significance of this formula is that the Krylov iteration method does not actually need to know the Jacobian matrix during the solution process. J What exactly are all the elements? You only need to know... J Acting on a vector v The result (i.e., matrix-vector product) This result can be obtained by evaluating the function twice (calculating...). and This is approximated by using two relatively low-cost residual calculations (function evaluations) instead of one extremely costly Jacobian matrix assembly and storage.

[0078] Preconditioning: Although Krylov's method is powerful, its convergence speed can be very slow if the condition number of the original linear equation system is poor (ill-conditioned). Preconditioning techniques are used to solve this problem.

[0079] The specific idea is to solve systems of linear equations. Jδu =- F First, multiply by a "good" matrix on the left or right. P -1This transforms it into a new system of equations that is easier to solve (with better condition numbers), for example:

[0080] (4);

[0081] This matrix P This is called a preconditioner. A good preconditioner... P Two conditions should be met: 1) It should resemble the Jacobian matrix as much as possible. J ,so P -1 J When the matrix is ​​close to the identity matrix, the system of equations becomes much easier to solve; 2) Solving P -1 y The computational cost of this operation is very low. In practical applications, an exact Jacobian matrix is ​​not required. J Therefore, a relatively simple and easily computed approximate Jacobian matrix (such as a version containing only the diagonal or block diagonal) can be used as the preconditioner. P .

[0082] Step S3: Cell deletion criterion and execution based on ablation depth. After convergence is calculated at each time step, the following operations are performed to update the mesh topology:

[0083] S31, Cumulative ablation depth calculation: based on the current time step Δ t and the maximum ablation rate calculated on the current ablated surface. v `_max` updates the total cumulative ablation depth `S`. The calculation formula is: `S_new = S_old + ...` v _max *Δ t。

[0084] S32, Element Deletion Decision: Traverse each element in the mesh. Obtain the geometric center coordinates y_e of that element. Determine the element's existence or deletion based on the following criteria:

[0085] Calculate the remaining thickness of the current material: H_current = H - S_new;

[0086] If y_e exceeds the height of the existing material (i.e., y_e ≥ H_current), then the cell should be deleted.

[0087] Otherwise, the unit should be reserved.

[0088] S33, Element Deletion Execution: Removes all elements determined to be deleted from the finite element mesh. This operation directly modifies the mesh topology, forming a new ablation surface.

[0089] Specifically, step S3 is one of the key points of the technical solution of this invention. The processor is data-coupled with the enhanced ablation rate field. The processor is set to be activated and executed after the computational task at each time step has fully converged. The initial thickness H of the material is recorded, and the cumulative ablation depth S is initialized to 0. In each time step, the maximum ablation rate on the current ablation surface is first determined. v _max, In this case, the ablation process on the ablation surface is uniform because the boundary conditions of the ablation surface are uniform, which causes the top element to ablate and retreat uniformly. Therefore, a representative ablation rate value is taken to replace all the top elements.

[0090] Cumulative ablation depth calculation: based on the current time step Δ t and the maximum ablation rate calculated on the current ablated surface. v `_max` updates the total cumulative ablation depth `S`. The calculation formula is: `S_new = S_old + ...` v _max * Δ t。

[0091] Cell deletion determination: Traverse each cell in the mesh. Obtain the geometric center coordinates y_e of the cell. Determine whether to retain or delete the cell based on the following criteria:

[0092] Calculate the remaining thickness of the current material: H_current = H - S_new;

[0093] If the center position y_e of the cell exceeds the height of the existing material (i.e., y_e ≥ H_current), then the cell should be deleted.

[0094] Otherwise, the unit should be reserved.

[0095] Element deletion execution: Removes all elements determined to be deleted from the finite element mesh. This operation directly modifies the mesh topology, forming a new ablation surface.

[0096] Step S4: Dynamic boundary identification and update. After a cell is deleted, the boundary information must be updated for the calculation of the next time step. This includes:

[0097] S41, New Boundary Identification: Traverse all neighboring cells of the deleted cell. The inner boundaries that were originally adjacent to the deleted cell are now exposed as new outer boundaries.

[0098] S42, Boundary Condition Redirection: Identify and mark these newly exposed boundaries as new "ablation surface" boundaries. In the next time step, the thermal flux boundary conditions calculated in step S2 will be applied to this new surface. Specifically, after traversing all cells with ablation surfaces, perform a topology modification operation on the cells in the "to-be-deleted list": First, mark the newly exposed boundary surfaces as new "ablation surfaces" by checking the neighbors of these cells.

[0099] S43, System Update Notification: Notifies all modules of the numerical computation system that the mesh topology has changed, forcing the next computation to use the updated mesh information and avoiding errors caused by using outdated data. Specifically, it sends a "mesh updated" signal to the entire computation system, forcing all modules that depend on mesh geometry (such as solvers, boundary condition processors, etc.) to refresh their internal state before the start of the next time step to adopt the latest mesh information.

[0100] Step S5: Advance the time step, repeat steps S2 to S4 until the preset total simulation time is reached.

[0101] Based on the above embodiments, in other embodiments, a dynamic mesh processing method for the ablation retreat of composite material surfaces is specifically provided. Figure 2 This is a flowchart illustrating the overall computational process of the method in this embodiment. The flowchart details how the method of this embodiment achieves complex physical process coupling and dynamic mesh management through a modular and sequential approach within a complete time step cycle. Specific steps include:

[0102] Step 1, Initialization: Set the initial time t =0s, and initialize the core state variable "cumulative ablation depth S" to 0. This ensures the repeatability and deterministic starting point of the simulation.

[0103] Step 2, Thermal-Ablation Coupled Solution: After entering the time step loop, the system first performs a coupled solution for thermal and ablation. Sub-step S21 in the above embodiment is the core physics calculation step, which calculates the ablation rate of the current material surface based on the temperature field of the previous moment. v and net heat flow q _net. Subsequently, in sub-step S22 of the above embodiment, net heat flow is applied as a boundary condition to the model, and the internal heat conduction equation is solved to update the temperature field. T These two sub-steps form a tightly coupled iteration, controlled by the judgment of "convergence at the current time step", ensuring that the thermal-ablation interaction has reached a stable solution before entering the next physical process.

[0104] Step 3, Ablation Criterion and Mesh Removal: After the thermal-ablation coupled solution converges, the mesh processing stage begins. In the above embodiment, sub-step S31 is based on the maximum surface ablation rate obtained in step S2. v _max, update the cumulative ablation depth S_new = S_old + v _max *Δ t (S_new is the current ablation depth, and S_old is the ablation depth of the previous time step). In the above embodiment, sub-step S32 iterates through all mesh elements, comparing their geometric coordinates y_e with the current remaining material thickness (H - S_new) to determine whether an element should be deleted. If the list of elements to be deleted is not empty, proceed to step four.

[0105] Step four involves dynamic boundary update and element deletion operations. The system removes elements while simultaneously reconstructing a new surface topology. If no elements need to be deleted, this step is skipped.

[0106] Step 5, Time Advancement and Loop Control: After completing the mesh operation, the simulation time is advanced by one step Δ. t Finally, the current time is checked using the "time step loop" judgment. t Is it less than the end time? t If the value is _end, return to step two to continue the calculation for the next time step; otherwise, the simulation ends.

[0107] Figure 2 This clearly demonstrates how the method of the present invention decomposes complex physical problems into independent, controllable computational steps, and organically links them together through rigorous logical judgment, thereby achieving stable and accurate dynamic ablation simulation.

[0108] Figures 3a-3f This is a cloud map showing the calculation results of a two-dimensional flat plate ablation example performed using the method described in this invention, specifically illustrating the process from the initial state ( t =0s) until the end of the simulation ( t During the period of 30s, the evolution of the internal temperature field of the material and the material surface retreat process due to ablation.

[0109] Figure 3a Showing t The initial state at y = 0s. At this moment, the entire material is at a uniform initial temperature (300K), and the upper surface of the material is at an initial height of y = 0.0505m. Figure 3b and Figure 3c They were shown respectively t =5s and tThe state at 10s. It can be seen that, influenced by the top heat flow boundary, the surface temperature of the material rises rapidly, and heat begins to conduct into the material, forming a significant temperature gradient. Simultaneously, the upper surface of the material has slightly receded, and the maximum value of the y-coordinate has decreased, which visually demonstrates the effect of the mesh deletion function of this invention. Figure 3d , Figure 3e and Figure 3f Showing t The states at 15s, 20s, and 30s. As time progresses, the high-temperature zone penetrates deeper into the material, indicating that the heat conduction process is ongoing. (Comparison) Figure 3a and Figure 3f It can be seen that during the 30-second ablation process, the total thickness of the material has decreased by about 0.01m (from 0.0505m to about 0.00445m, the 32*101 mesh layout has become 32*89, the number of meshes in the y direction has decreased by 12, and the total number of elements has decreased by 384).

[0110] This series of cloud maps powerfully demonstrates the effectiveness and accuracy of the method described in the embodiments of the present invention. It not only accurately simulates the unsteady thermal response within materials but also clearly and intuitively reproduces the macroscopic geometric changes caused by ablation, verifying the superiority of the present invention in handling complex moving boundary problems.

[0111] The units described in the embodiments of the present invention can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the specific unit itself.

[0112] According to one aspect of the present invention, a computer program product or computer program is provided, the computer program product or computer program including computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and executes the computer instructions, causing the computer device to perform the methods provided in the various optional implementations described above.

[0113] In another aspect, embodiments of the present invention also provide a computer-readable medium, which may be included in the electronic device described in the above embodiments; or it may exist independently and not assembled into the electronic device. The computer-readable medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform the methods described in the above embodiments.

Claims

1. A method for dynamic mesh processing for ablation of a composite material surface, characterized in that, The method comprises the following steps: S1, model initialization and parameter definition; S2, after determining the model and parameters, coupling solving of material surface ablation and thermal response, S3, after obtaining the material surface ablation and thermal response, ablation depth-based unit deletion criterion and execution are performed; S4, after unit deletion, dynamic boundary identification and update are performed; S5, time step is advanced, and steps S2 to S4 are repeated until a preset total simulation time length is reached; In step S3, the ablation depth-based unit deletion criterion and execution specifically comprise the following sub-steps: S31, cumulative ablation depth calculation: according to the current time step Δ t and the calculated maximum ablation rate on the current ablation surface v _max, update the total cumulative ablation depth S, the calculation formula is: S_new = S_old + v _max * Δ t ; S_new is the current ablation depth, S_old is the ablation depth of the previous time step; S32, unit deletion determination: each unit in the grid is traversed, the geometric center coordinate y_e of the unit is obtained, and the following criterion is used to determine whether the unit should be deleted or not: Calculate the remaining thickness of the current material: H_current = H - S_new; If y_e has exceeded or is equal to the height of the existing material, y_e ≥ H_current is satisfied, it is determined that the unit should be deleted; otherwise, the unit should be retained; H is the initial thickness; S33, unit deletion execution: the units determined to be deleted are removed from the finite element grid; In step S33, the removal specifically directly modifies the topology of the grid, thereby forming a new ablation surface; In step S4, the dynamic boundary identification and update specifically comprise the following sub-steps: S41, new boundary identification: all adjacent units of the deleted unit are traversed, and the original inner boundary adjacent to the deleted unit is now exposed to become a new outer boundary; S42, boundary condition redirection: the newly exposed boundaries are identified and marked as new "ablation surface" boundaries; S43, system update notification: notify all modules of the numerical calculation system that the grid topology has changed, and use the updated grid information for the next calculation.

2. The method of claim 1, wherein, In step S1, the model initialization specifically establishes an initial finite element grid model describing the structure to be analyzed, which has an initial geometric shape, size and initial thickness.

3. The method of claim 1, wherein, In step S1, the parameter definition specifically determines environmental parameters and thermal physical parameters.

4. The method of claim 3, wherein, The environmental parameters include the recovery enthalpy of the flow, the reference cold wall heat flow, the gas pressure and the gas composition; the thermal physical parameters include the density, the specific heat and the function changing with temperature.

5. The method of claim 1, wherein, In step S2, the coupling solving of material surface ablation and thermal response specifically comprises the following sub-steps: S21, surface heat flux calculation: according to the current wall temperature and environmental parameters, the ablation rate of the material surface and the net heat flux generated by convection, radiation and chemical reaction are calculated by solving the surface chemical reaction equilibrium and energy balance equation q _net; S22, heat conduction analysis: the net heat flux calculated in step S21 is applied as a boundary condition on the current material ablation surface, the transient heat conduction equation inside the structure is solved, and the updated temperature field distribution in the entire domain is obtained; q _net, as a boundary condition, is applied on the current material ablation surface, the transient heat conduction equation inside the structure is solved, and the updated temperature field distribution in the entire domain is obtained; S23, repeat steps S21 and S22 until the temperature and heat flow in the current time step converge, to obtain a stable and consistent temperature field and ablation rate at the current time.

6. The method of claim 5, wherein, In step S21, the ablation rate of the material surface specifically includes the mass loss rate and the linear recession rate.

7. A dynamic mesh processing system for ablating a surface of a composite material back, characterized in that, The computer device comprises a processor and a memory, and the memory stores a computer program which, when loaded by the processor, executes the method of any one of claims 1-6.

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