Dynamic grid processing method and system for composite material surface ablation retrogression

Abstract

The invention discloses a dynamic grid processing method and system for composite material surface ablation retrogression, and belongs to the field of computational mechanics and heat transfer science, and the method comprises the following steps: S1, model initialization and parameter definition; s2, after a model and parameters are determined, material surface ablation and thermal response are solved in a coupling mode; s3, after material surface ablation and thermal response are obtained, unit deletion criteria and execution based on the ablation depth are carried out; s4, after the units are deleted, dynamic boundary recognition and updating are executed; and S5, advancing the time step, and repeating the step S2 to the step S4 until a preset total simulation time length is reached. The method not only can accurately simulate the unsteady state thermal response in the material, but also can clearly and intuitively reproduce the macroscopic geometric shape change caused by ablation, and has superiority in processing the complex moving boundary problem.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of computational mechanics and heat transfer, and more particularly, to a dynamic mesh processing method and system for ablative recession of composite material surfaces. BACKGROUND

[0002] When a vehicle flies at high speed, the heat-resistant material on its surface will undergo severe aerodynamic heating, leading to physical and chemical changes in the material, i.e., "ablation". Ablation can cause material mass loss and changes in surface topography (referred to as "ablation recession"), which has a significant impact on the heat transfer performance and structural integrity of the material.

[0003] In traditional finite element analysis, simulating such moving boundary problems usually adopts Arbitrary Lagrangian-Eulerian (ALE) method or Immersed Boundary Method. ALE method adapts to boundary changes by moving and restructuring the mesh, but when the amount of ablation is large, it is easy to produce severe mesh distortion, leading to a decrease in calculation accuracy or even non-convergence. Although the Immersed Boundary Method can handle complex geometric changes, it is complex to implement and has difficulties in accurately applying boundary conditions. Another method is Element Birth and Death technology, which pre-defines a mesh containing the region that may be ablated in the future, and "kills" the elements according to the criteria during the calculation process. However, the traditional Element Birth and Death technology usually only multiplies the stiffness matrix of the element by a very small factor, and the element still exists in the mesh, which increases unnecessary computational burden. A more direct method is to directly delete the element from the mesh, but this brings new technical challenges: 1) Boundary update: When surface elements are deleted, their internal neighboring elements become new surface elements. There must be a reliable mechanism to identify these newly exposed faces and update them as new surface boundaries in order to correctly apply aerodynamic heat, pressure and other loads.

[0004] 2) Data consistency: Changes in mesh topology must be notified to all relevant computing modules (such as solvers, boundary conditions, material models, etc.) to prevent the use of outdated and invalid mesh information (such as cached element pointers or boundary data), which can cause program crashes.

[0005] 3) Ablation criterion: An accurate and efficient criterion is needed to determine which elements should be deleted at the current time step.

[0006] Therefore, the existing technology has problems such as mesh distortion, unstable calculation, and difficulty in boundary update when dealing with large-scale ablation recession. There is an urgent need for a mesh processing scheme that can accurately simulate ablation recession, dynamically update the surface boundary, and tightly couple with the finite element framework. SUMMARY

[0007] The present application aims at overcoming the deficiencies of the prior art, and provides a composite material surface ablation retreat dynamic grid processing method and system, which avoids the problem of grid distortion, has the advantages of high calculation efficiency, high precision and simple implementation.

[0008] The purpose of the present application is achieved by the following scheme: A dynamic grid processing method for composite material surface ablation retreat, comprising the following steps: S1, model initialization and parameter definition; S2, after determining the model and parameters, coupling solving material surface ablation and thermal response, S3, after obtaining the material surface ablation and thermal response, based on the ablation depth unit deletion criterion and execution; S4, after the unit is deleted, dynamic boundary identification and update are performed; S5, time step advancing, repeating steps S2 to S4 until the preset total simulation time is reached.

[0009] Further, 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.

[0010] Further, in step S1, the parameter definition specifically determines the environmental parameters and thermal physical parameters.

[0011] Further, the environmental parameters include the recovery enthalpy of the flow, the reference cold wall heat flow, the gas pressure and the gas component; the thermal physical parameters include the density, the specific heat and the function changing with temperature.

[0012] Further, in step S2, the coupling solving material surface ablation and thermal response specifically includes the following sub-steps: S21, surface heat flow calculation: according to 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 reaction are calculated by solving the surface chemical reaction equilibrium and energy balance equation q _net; S22, heat conduction analysis: the net heat flow q _net calculated in step S21 is applied as a boundary condition on the current material ablation surface, and the transient heat conduction equation inside the structure is solved to obtain the updated temperature field distribution in the entire structure domain; S23, repeating 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.

[0013] Further, in step S21, the ablation rate of the material surface specifically includes the mass loss rate and the linear retreat rate.

[0014] Further, in step S3, a unit deletion criterion based on the ablation depth is executed, specifically including sub-steps of: 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: traverse each unit in the grid, get the geometric center coordinates y_e of the unit, and determine whether the unit should be deleted or not according to the following criterion: Calculate the remaining thickness of the current material: H_current = H - S_new; If y_e has exceeded or 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: remove the units determined to be deleted from the finite element grid.

[0015] Further, in step S33, the removal specifically directly modifies the topology of the grid, thereby forming a new ablation surface.

[0016] Further, in step S4, the dynamic boundary identification and update is executed, specifically including sub-steps of: S41, new boundary identification: traverse all adjacent units of the deleted unit, the inner boundary originally adjacent to the deleted unit is now exposed as a new outer boundary; S42, boundary condition redirection: identify and mark these newly exposed boundaries as new "ablation surface" boundaries; S43, notify system update: notify all modules of the numerical calculation system that the grid topology has changed, and use the updated grid information for the next calculation.

[0017] A dynamic grid processing system for composite material surface ablation recession, comprising a computer device, the computer device comprising a processor and a memory, the memory storing a computer program, when the computer program is loaded by the processor, the method as claimed in any one of the above is executed.

[0018] The beneficial effects of the present application include: (1) Avoid grid distortion completely: the method of the present application uses fixed Eulerian grid, simulates boundary movement by deleting elements rather than moving nodes, fundamentally avoids the problem of severe grid distortion and calculation failure encountered by ALE method under large deformation, greatly enhances the robustness of numerical simulation.

[0019] (2) High computational efficiency: compared with the complex global grid reconstruction method, the element deletion and local boundary update operation of the present application is simpler, more efficient, and has small computational overhead, especially suitable for simulating long time and large ablation process.

[0020] (3) High precision and easy to implement: the method of the present application can clearly track the ablation front, and the newly formed ablation surface is accurately composed of a series of element boundary surfaces. The application of boundary conditions directly acts on these new boundaries, ensuring the accuracy of heat flow calculation. The whole algorithm logic is clear and easy to implement in the existing finite element framework.

[0021] (4) Strong universality: the method of the present application is not only suitable for thermal ablation problems, but also can be extended to other moving boundary problems involving material removal, especially like the ablation problem of flat head body, has broad application prospect in the fields such as electrochemical corrosion, mechanical wear, etc.

[0022] (5) The present application can not only accurately simulate the non-steady thermal response in the material, but also clearly and intuitively reproduce the macroscopic geometric shape change caused by ablation, which has advantages in dealing with complex moving boundary problems. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0024] Figure 1a The physical model of the ablation retreat physical calculation model; Figure 1b The calculation grid of the ablation retreat physical calculation model; Figure 2 The ablation retreat calculation flowchart based on grid deletion; Figure 3a The ablation retreat calculation result based on grid deletion at t = 0s temperature distribution diagram; Figure 3b The ablation retreat calculation result based on grid deletion at t = 5s temperature distribution diagram; Figure 3c Temperature distribution map at t = 10s for the ablation recession calculation result based on grid deletion t Figure 3d Temperature distribution map at t = 15s for the ablation recession calculation result based on grid deletion t Figure 3e Temperature distribution map at t = 20s for the ablation recession calculation result based on grid deletion t Figure 3f Temperature distribution map at t = 30s for the ablation recession calculation result based on grid deletion t DETAILED DESCRIPTION

[0025] All features disclosed in the specification and / or steps of methods disclosed in the specification can be combined and / or extended or replaced, except for mutually exclusive features and / or steps, in any manner possible, unless otherwise explicitly indicated.

[0026] The specific implementation process of the present application is as follows: To solve the problems in the background, the present application specifically proposes a dynamic grid processing method for composite material surface ablation recession, which can effectively process the gradual material removal caused by composite material ablation recession under the coupling of multi-physical field finite element simulation framework, and dynamically update the calculation domain boundary and maintain numerical stability in the process. Therefore, the present application aims to solve the following technical problems encountered by the existing numerical simulation method in processing large-scale ablation problems: 1) grid distortion problem under large deformation: how to avoid the grid distortion and calculation failure caused by the large recession of the material surface in the traditional Lagrange method. 2) balance problem between calculation efficiency and accuracy: how to develop an effective method with low calculation cost, but also accurately capture the ablation boundary movement and thermal-structural response. 3) accurate application of dynamic boundary problem: how to accurately apply the boundary conditions such as aerodynamic heat flow in the process of continuously forming new boundaries due to ablation of the material, in order to ensure the correctness of the temperature field calculation.

[0027] In a preferred embodiment, a numerical method for simulating the recession of material surface ablation in high temperature environment in finite element calculation and analysis is specifically disclosed, and a technical solution for simulating the change of material surface topography by dynamically deleting grid elements is particularly disclosed. In a specific concept, the method of the embodiment of the present application performs heat conduction analysis on a fixed Euler grid, and dynamically deletes elements representing ablated material through a suitable criterion, thereby simulating the recession of the material surface.

[0028] Taking the heating of a cylindrical topography heat protection structure as an example, a two-dimensional cross-sectional schematic diagram is given here, as shown in Figure 1a and Figure 1b ​​​​The dynamic material loss, i.e. the grid deletion process, is analyzed. For example, a carbon-based composite material plate with an initial height of 50.5 mm and a width of 16 mm is continuously heated by a high-temperature gas flow on its upper surface to cause ablation. The bottom surface of the plate is kept at a constant temperature of 300 K, and the two side surfaces are considered to be adiabatic. This embodiment aims to simulate the ablation process of the plate within 30 seconds, and the calculation results are shown in Figures 3a to 3f The method of the embodiment of the present application specifically includes the following steps: Step S1: model initialization and parameter definition S11, an initial finite element grid model describing the structure to be analyzed is established, which has an initial geometric shape and size, and an initial thickness H.

[0029] S12, environmental parameters are determined, including the recovery enthalpy of the incoming flow, the reference cold wall heat flux, the gas pressure, the gas composition, etc.

[0030] S13, the thermal physical property parameters of the material are determined, including the functions of density, specific heat, thermal conductivity, etc. varying with temperature.

[0031] Specifically, first, a two-dimensional rectangular calculation domain representing the plate is established and discretized into a finite element grid, for example, divided into 32*101 quadrilateral elements, as shown in Figure 1a and Figure 1b Secondly, a variable for describing the temperature distribution is defined in the system, and its initial value is set to 300 K. At the same time, an auxiliary physical field variable can be additionally defined to store and transfer the modified or enhanced ablation rate (considering the mechanical ablation effect).

[0032] Physical model and parameter configuration: environmental conditions are defined by parameterizing the high-temperature gas flow environment as a set of input data, including the recovery enthalpy of the flow, the reference cold wall heat flux value, the gas pressure, etc. Here, the relevant parameter settings are given, including: recovery enthalpy 8.051e6 J / kg, cold wall heat flux 18.338e6 W / m 2, cold wall hot flow reference wall temperature 0 K, total pressure 5.901 atm, oxygen partial pressure 1.23921 atm, nitrogen partial pressure 4.66179 atm, air molar mass 0.02897 kg / mol. Ablation physical model: define a calculation module for calculating the surface ablation of carbon materials. The function of this module is to calculate the surface linear ablation rate of the material according to the current surface temperature of the material and the external environmental conditions by solving the relevant physical and chemical equations. Surface energy flow model: define a calculation module for calculating the surface net heat flow. This module takes into account various effects such as convection, radiation and chemical reaction, and calculates the final net heat flux applied to the material surface based on the current surface temperature and the intermediate results of ablation calculation (such as catalytic recombination and chemical reaction heat release). Ablation enhancement model: in order to simulate more complex physical phenomena such as mechanical ablation, a derived data calculation module can be configured. The function of this module is to obtain the basic linear ablation rate and process it (for example, multiply it by an enhancement factor greater than 1) to obtain an equivalent ablation rate considering the enhancement effect.

[0033] Boundary condition configuration: on the bottom surface boundary of the model, a fixed temperature of 300 K is applied as a boundary condition; on the left and right side boundaries, an adiabatic boundary condition with zero heat flux is applied; on the upper surface (i.e. the top, initial ablation surface) of the model, a heat flow boundary condition coupled with the physical model is applied. The value of this boundary condition is not a fixed value, but a dynamically obtained net heat flux calculated from the above-mentioned "surface energy flow model".

[0034] Step S2: coupling the solution of surface ablation and thermal response, the following coupled iterative calculation should be performed within a calculation time step: S21, surface heat flow calculation: according to the current wall temperature and environmental parameters, the ablation rate (mass loss rate and linear recession rate) of the material surface and the net heat flow generated by convection, radiation and chemical reaction are calculated by solving the surface chemical reaction equilibrium and energy balance equations q _net.

[0035] S22, heat conduction analysis: the net heat flow q _net calculated in step S21 is applied as a boundary condition on the current material ablation surface, and the transient heat conduction equation inside the structure is solved to obtain the updated temperature field distribution in the entire domain.

[0036] S23, repeat steps S21, 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.

[0037] Specifically, according to the current wall temperature and environmental parameters, the ablation rate (mass loss rate and linear recession rate) of the material surface and the net heat flow generated by convection, radiation and chemical reaction are calculated by solving the surface chemical reaction equilibrium and energy balance equation q _net. The net heat flow q _net is applied as a boundary condition on the current material ablation surface, and the transient heat conduction equation inside the structure is solved to obtain the updated temperature field distribution in the entire structure domain.

[0038] The transient analysis method is used for solving, such as the pre-processed Jacobian-free Newton-Krylov method, and the time step adaptive adjustment mechanism is configured to improve the efficiency under the premise of ensuring the convergence of the calculation. The following is a brief introduction to the Jacobian-free Newton-Krylov method.

[0039] Newton Method: For a nonlinear equation system F ( u )=0, the standard Newton method finds the next approximate solution u k by linearizing near the current solution u k+1 : (1); (2); where is the Jacobian matrix (Jacobian Matrix), which represents the first-order derivative of the function F with respect to the variable u . Solving this linear equation system is the key to each step of the Newton method.

[0040] Krylov Subspace Method: When the problem size is very large, the computational cost of directly solving the above linear equation system (i.e. calculating the inverse J -1 of the Jacobian matrix) is very high. Therefore, an iterative method is usually used to approximate the solution, and the Krylov subspace method is considered here, such as GMRES (Generalized Minimal Residual method). The core of this method is to find an approximate solution to the linear equation system in a low-dimensional space of a "Krylov subspace", avoiding the direct calculation of the inverse of the matrix, and being more efficient.

[0041] Jacobian-Free: This is the essence of the pre-processed Jacobian-free Newton-Krylov method. In the current ablation problem, the Jacobian matrixJ The form is very complex, and it is extremely difficult and error-prone to derive and program the implementation manually. The "no-Jacobian" method cleverly bypasses this problem, the core of which is the use of a mathematical approximation: (3); where, is a vector, is a small quantity. The significance of this formula is that in the process of solving the Krylov iteration method, it is actually not necessary to know what all the elements of the Jacobian matrix J are, but only to know the result of J acting on a vector v (that is, the matrix-vector product ). And this result can be approximated by twice the function evaluation (calculate and ). That is, the cost of two relatively low residual calculations (function evaluation) instead of once the cost of assembling and storing the Jacobian matrix.

[0042] Preconditioning: Although the Krylov method is very powerful, if the condition number of the original linear equation system is very poor (ill-conditioned), the convergence speed will be very slow. Preconditioning technology is used to solve this problem.

[0043] The specific idea is to multiply a "good" matrix Jδu F on the left or right before solving the linear equation system P -1 , so that it becomes a new equation system that is easier to solve (better condition number), for example: (4); This matrix P is called a preconditioner. A good preconditioner P should meet two conditions: 1) it should be as "similar" to the Jacobian matrix J as possible, so that P -1 J is close to the identity matrix, and the equation system becomes easy to solve; 2) the computational cost of solving P -1 y This operation should be very low. In practical applications, an accurate Jacobian matrix J is not required, so a relatively simple and easy-to-calculate approximate Jacobian matrix (such as one containing only the diagonal or block diagonal) can be used as a preconditioner P .

[0044] ​Step S3: Unit deletion criterion and execution based on ablation depth. After the convergence of the calculation at each time step, the following operations are performed to update the mesh topology: S31, cumulative ablation depth calculation: update the total cumulative ablation depth S according to the current time step Δ t and the maximum ablation rate calculated on the current ablation surface v _max. The calculation formula is: S_new = S_old + v _max * Δ t。

[0045] S32, unit deletion determination: traverse each unit in the mesh. Obtain the geometric center coordinate y_e of the unit. Determine whether the unit should be deleted or not according to the following criterion: Calculate the remaining thickness of the current material: H_current = H - S_new; If y_e has exceeded the height of the existing material (i.e., y_e ≥ H_current), it is determined that the unit should be deleted.

[0046] Otherwise, the unit should be retained.

[0047] S33, unit deletion execution: remove all units determined to be deleted from the finite element mesh. This operation directly modifies the topology of the mesh, forming a new ablation surface.

[0048] Specifically, step S3 is one of the key points of the technical solution of the present application. The processor is coupled with the enhanced ablation rate field. The processor is activated and executed after the calculation task of the processor at each time step is completely converged. Record the initial thickness of the material H, and initialize the cumulative ablation depth S to 0. In each time step, first determine the maximum ablation rate v _max on the current ablation surface, which is a uniform ablation process in this case because the boundary conditions of the ablation surface are uniform, resulting in uniform ablation of the top units, so a representative ablation rate value is taken instead of all top units.

[0049] Cumulative ablation depth calculation: update the total cumulative ablation depth S according to the current time step Δ t and the maximum ablation rate calculated on the current ablation surface v _max. The calculation formula is: S_new = S_old + v _max * Δ t。

[0050] Unit deletion determination: traverse each unit in the mesh. Obtain the geometric center coordinate y_e of the unit. Determine whether the unit should be deleted or not according to the following criterion: Calculate the remaining thickness of the current material: H_current = H - S_new; If the cell center position y_e has exceeded the height of the existing material (i.e. y_e ≥ H_current), then it is determined that the cell should be deleted.

[0051] Otherwise, the cell should be kept.

[0052] Cell deletion execution: remove all cells determined to be deleted from the finite element mesh. This operation directly modifies the topology of the mesh, forming a new ablation surface.

[0053] Step S4: Dynamic boundary identification and update, after cell deletion, boundary information must be updated for the next time step calculation, including: S41, new boundary identification: traverse all adjacent cells of the deleted cell. The original inner boundary adjacent to the deleted cell is now exposed as a new outer boundary.

[0054] S42, boundary condition redirection: identify and mark these newly exposed boundaries as new "ablation surface" boundaries. In the next time step, the heat flux boundary condition calculated in step S2 will be applied to this new surface. Specifically, after traversing all cells of the ablation surface, perform a topological modification operation on the cells in the "to-be-deleted list": first, by checking the neighbors of these cells, mark the newly exposed boundary surface as the new "ablation surface".

[0055] S43, notify system update: notify all modules of the numerical calculation system that the mesh topology has changed, forcing the use of updated mesh information for the next calculation to avoid errors caused by the use of outdated data. Specifically, send a "mesh updated" signal to the entire calculation system, forcing all modules that depend on the mesh geometry (such as the solver, boundary condition processor, etc.) to refresh their internal state before the next time step begins, to adopt the latest mesh information.

[0056] Step S5: Time step advancement, repeat steps S2 to S4 until the pre-set total simulation time is reached.

[0057] Based on the above embodiment, in other embodiments, a dynamic mesh processing method for composite material surface ablation recession is specifically provided, Figure 2 The overall calculation flowchart of the embodiment method is shown in the figure. The flowchart details how the embodiment method of the present application realizes complex physical process coupling and dynamic mesh management in a complete time step cycle through modularization and serialization, and the specific steps include: Step 1, initialization: set the initial time t=0s, and the core state variable "cumulative ablation depth S" is initialized to 0. This ensures the reproducibility and deterministic starting point of the simulation.

[0058] Step two, heat-ablation coupling solution: After entering the time step loop, the system first performs the coupling solution of heat and ablation. Sub-step S21 in the above embodiment is the core physical calculation link, which calculates the ablation rate of the current material surface according to the temperature field at the last time v and the net heat flow q _net. Thereafter, sub-step S22 in the above embodiment applies the net heat flow as a boundary condition to the model, and solves the internal heat conduction equation to update the temperature field T . These two sub-steps form a tightly coupled iteration, which is controlled through the "current time step convergence" judgment, to ensure that the interaction of heat and ablation has reached a stable solution before entering the next physical process.

[0059] Step three, ablation criterion and grid deletion: after the heat-ablation coupling solution converges, the grid processing stage is entered. Sub-step S31 in the above embodiment updates the cumulative ablation depth S_new = S_old + v _max * Δ v according to the maximum surface ablation rate t _max obtained in step S2 (S_new is the current ablation depth, and S_old is the ablation depth of the previous time step). Through sub-step S32 in the above embodiment, all grid elements are traversed, and their geometric coordinates y_e are compared with the current material remaining thickness (H-S_new) to determine whether the element should be deleted. If the to-be-deleted list is not empty, step four is entered.

[0060] Step four, dynamic boundary update and element deletion operation: the system removes elements and reconstructs the new surface topology at the same time. If no element needs to be deleted, this step is skipped.

[0061] Step five, time advancement and loop control: after the grid operation is completed, the simulation time is advanced by one step Δ t . Finally, the "time step loop" judgment checks whether the current time t is less than the end time t _end. If yes, the calculation of the next time step is continued by returning to step two; if no, the simulation is ended.

[0062] Figure 2 The embodiment method of the present application clearly shows how to decompose complex physical problems into independent and controllable calculation steps, and organically link them together through rigorous logical judgment, thereby realizing stable and accurate dynamic ablation simulation.

[0063] Figures 3a to 3fThis 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.

[0064] 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 t The 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).

[0065] 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.

[0066] 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.

[0067] According to an aspect of an embodiment of the present application, there is provided a computer program product or computer program, comprising 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 the processor executes the computer instructions to cause the computer device to perform the method provided in the various optional implementation manners described above.

[0068] As another aspect, the embodiment of the present application further provides a computer readable medium, which can be included in the electronic device described in the above embodiments, or can exist separately without being 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 implement the method described in the above embodiments.

Claims

1. A dynamic mesh processing method for the ablation retreat of composite material surfaces, characterized in that, Includes the following steps: S1, Model initialization and parameter definition; S2, after determining the model and parameters, couple the solution of material surface ablation and thermal response. S3, after obtaining the ablation and thermal response of the material surface, the cell deletion criterion and execution are based on the ablation depth; S4, After the cell is deleted, perform dynamic boundary identification and update; S5, advance the time step, repeat steps S2 to S4 until the preset total simulation time is reached.

2. The dynamic mesh processing method for ablation retreat of composite material surface according to claim 1, characterized in that, In step S1, the model initialization specifically establishes an initial finite element mesh model describing the structure to be analyzed. This model has an initial geometric shape, size, and initial thickness.

3. The dynamic mesh processing method for ablation retreat of composite material surface according to claim 1, characterized in that, In step S1, the parameter definition specifically determines the environmental parameters and thermophysical parameters.

4. The dynamic mesh processing method for ablation retreat of composite material surface according to claim 3, characterized in that, 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.

5. The dynamic mesh processing method for ablation retreat of composite material surface according to claim 1, characterized in that, In step S2, the coupled solution of material surface ablation and thermal response specifically includes the following sub-steps: 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; 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. 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.

6. The dynamic mesh processing method for ablation retreat of composite material surface according to claim 5, characterized in that, In step S21, the ablation rate of the material surface specifically includes the mass loss rate and the line retreat rate.

7. The dynamic mesh processing method for ablation retreat of composite material surface according to claim 1, characterized in that, Step S3, the cell deletion criterion based on ablation depth and its execution, specifically includes the following sub-steps: 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. 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: Calculate the remaining thickness of the current material: H_current = H - S_new; 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. S33, Element Deletion Execution: Removes the elements that are determined to be deleted from the finite element mesh.

8. The dynamic mesh processing method for ablation retreat of composite material surface according to claim 7, characterized in that, In step S33, the removal of the specific mesh topology directly modifies the structure, thereby forming a new ablation surface.

9. The dynamic mesh processing method for ablation retreat of composite material surface according to claim 1, characterized in that, In step S4, the dynamic boundary identification and update process specifically includes the following sub-steps: 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. S42, Boundary Condition Redirection: Identify and mark these newly exposed boundaries as new "ablation surface" boundaries; 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.

10. A dynamic mesh processing system for the ablation retreat of composite material surfaces, characterized in that, The device includes a computer device comprising a processor and a memory, wherein the memory stores a computer program that, when loaded by the processor, executes the method as described in any one of claims 1 to 9.

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