Particle positioning method and device for Euler-Lagrange two-phase flow simulation

Abstract

The invention provides a particle positioning method and device for Euler-Lagrange two-phase flow simulation. The method comprises the following steps: acquiring an initial particle position and a unit where the initial particle position is located; calculating the shortest time for the current particle position to reach each surface in the unit, and recording a corresponding surface sequence number; comparing the shortest time for the particles to reach each surface in the unit with the calculated time step length, and judging whether the particles are still in the unit or not; according to the technical scheme provided by the invention, rapid particle positioning and tracking of Euler-Lagrange two-phase flow simulation can be realized.

Description

Technical Field

[0001] This document relates to the field of particle positioning technology, and in particular to a particle positioning method and apparatus for Eulerian-Lagrange two-phase flow simulation. Background Technology

[0002] The transport and dispersion of solid particles in supersonic flows are widespread in various engineering and scientific research scenarios, such as dust particles in turbojet engines, metallic fuel particles in solid rocket ramjet engines, and drug microparticles in medical injections. To accurately simulate such gas-solid two-phase flows, a two-phase flow model based on the Eulerian-Lagrange framework is commonly used: the continuous phase (gas phase) is described by the complete gas governing equations in the Eulerian coordinate system, while the discrete phase (solid particles) is tracked by a particle trajectory model in the Lagrange coordinate system. This method can accurately record the particle trajectory and couple complex physicochemical processes such as phase transition and combustion, and has become the mainstream method for predicting rarefied gas-solid two-phase flows.

[0003] In Eulerian-Lagrange two-phase flow simulations, solving for particle motion requires locating and tracking each particle: locating determines which grid cell the particle is currently in, allowing us to obtain the gas flow field parameters at that location; tracking, on the other hand, determines the new grid cell the particle enters after a time step. Since this locating and tracking operation must be performed on all particles at each time step in the numerical simulation, the computational cost increases significantly with the number of particles and the grid size. Therefore, developing efficient and robust methods for fast particle location and tracking is crucial for improving overall computational efficiency.

[0004] Several particle localization and tracking algorithms have been proposed and applied, such as the Zhou-Leschziner algorithm, the Chen-Pereira algorithm, the R. Chorda algorithm, and the HNF algorithm. These methods have improved localization efficiency to some extent, but still suffer from high computational complexity, complex implementation, or limited adaptability. Therefore, a more efficient, stable, and easily implemented particle localization and tracking method is urgently needed to further improve the computational efficiency and engineering applicability of numerical simulations of gas-solid two-phase flows. Summary of the Invention

[0005] This invention provides a particle positioning method and apparatus for Eulerian-Lagrange two-phase flow simulation, aiming to solve the above-mentioned problems.

[0006] According to an embodiment of the present invention, a particle localization method for Eulerian-Lagrange two-phase flow simulation is provided, comprising: S1. Obtain the initial particle position and its cell; S2. Calculate the shortest time for the current particle position to reach each surface within the cell. And record the corresponding face number; S3. Compare the shortest times for particles to reach each surface within the cell. With calculation time step Determine whether the particle is still within the unit cell; S4. Record the particle location and its cell.

[0007] According to an embodiment of the present invention, a particle positioning device for Eulerian-Lagrange two-phase flow simulation is provided, comprising: Initialize the module to obtain the initial particle position and its cell; The shortest time calculation module calculates the shortest time for the current particle position to reach each face within the cell. And record the corresponding face number; The calculation module is used to compare the shortest time for particles to reach each surface within the cell. With calculation time step Determine whether the particle is still within the unit cell; The recording module is used to record the position of the particles and the cell in which they are located.

[0008] The embodiments of this invention enable efficient and accurate localization and tracking of particle motion in complex flow fields. This method intelligently determines whether a particle has crossed a cell boundary by calculating the shortest time for a particle to reach each face of a grid cell and comparing it with the calculation step size. This avoids the enormous computational overhead of traditional global search and significantly improves the computational efficiency of two-phase flow simulation. Furthermore, position updates based on rigorous geometric and kinematic formulas ensure the accuracy of particle trajectories. This scheme has a clear structure, high modularity, and is easy to integrate and apply, providing a reliable and practical technical means for high-fidelity numerical simulation of large-scale particle swarms. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in 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 recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a flowchart of a particle localization method for Eulerian-Lagrange two-phase flow simulation according to an embodiment of the present invention; Figure 2 This is a calculation diagram of the particle localization method for Eulerian-Lagrange two-phase flow simulation according to an embodiment of the present invention; Figure 3 This is a computational mesh diagram according to an embodiment of the present invention; Figure 4 The particle distribution map of the nozzle is obtained through calculation in an embodiment of the present invention; Figure 5 This is a comparison chart of calculation experiments in an embodiment of the present invention. Detailed Implementation

[0011] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0012] Method Implementation Examples According to embodiments of the present invention, a particle localization method for Eulerian-Lagrange two-phase flow simulation is provided. Figure 1 This is a flowchart of a particle localization method for Eulerian-Lagrange two-phase flow simulation according to an embodiment of the present invention. Figure 1 As shown, the particle localization method for Eulerian-Lagrange two-phase flow simulation according to an embodiment of the present invention specifically includes: S1. Obtain the initial particle position and its cell; The initial particle positions are given according to actual requirements. Taking the simulation of gas-solid two-phase flow in a solid rocket motor as an example, the initial particle positions are distributed at the engine inlet boundary, and are uniformly injected into the flow field from the center of each cell on the inlet grid surface according to the gas phase velocity.

[0013] S2. Calculate the shortest time for the current particle position to reach each surface within the cell. And record the corresponding face number; For all faces of the element containing the particle (the number of faces is determined by the mesh type), the time it takes for the particle to move to that face is calculated. The calculation formula is: ; In the formula , , These represent the velocities of the particle in the three directions (x, y, z) of a Cartesian coordinate system. , , These represent the positions of the particles. , , , Let be the coefficients of the following equation for the plane of the triangle.

[0014] ; After obtaining the times for all faces, select the smallest time that has physical significance. (i.e., the non-negative minimum value), and record the face number corresponding to the minimum time. .

[0015] S3. Compare the shortest times for particles to reach each surface within the cell. With calculation time step Determine whether the particle is still within the unit cell; Figure 2 For a specific judgment diagram, based on Figure 2 It can be seen that the shortest time for particles to reach each surface within the unit is compared. With calculation time step ,when When the particle is still in the original cell, particle tracking ends. This indicates that the particles pass through Proceed to the next unit For the new unit Repeat steps S2-S3 until the condition is met. ; S4. Record the particle location and its cell.

[0016] Particle position is ; ; ; The cell containing the particle is the last cell tracked in step three.

[0017] When performing the next time step calculation, the particle positions and elements obtained by the algorithm can be used as the initial particle positions and elements of step one.

[0018] Furthermore, after determining in S3 that a particle has entered a new cell, a step can be added to verify the validity of the new cell. Specifically, after determining candidate new cells based on the face number traversed by the particle and the mesh topology, it is verified whether the new position of the particle after moving according to the calculated shortest time is indeed located within the geometric space of the candidate cell. If not, a correction mechanism is triggered, such as re-searching in adjacent cells or using alternative second-shortest time faces for a secondary judgment. This extension enhances the robustness of the method under non-ideal meshes or extreme motion conditions.

[0019] Furthermore, the method can be integrated with a particle interaction processing module. Before executing S4 to record the final position and cell, a particle-particle collision detection and processing step is added: for particles located in the same final cell or multiple neighboring cells within the current time step, it is determined whether a collision has occurred based on their position, velocity, and physical properties. If a collision occurs, the velocity vector of the relevant particles is updated according to a preset collision model (such as a hard sphere model or a soft sphere model), and optionally, their final position at the end of the current time step is recalculated or fine-tuned before executing S4 for recording. This extension enables the method to simulate more realistic dense particle flow behavior.

[0020] Furthermore, the method supports collaboration with dynamic or adaptive meshes. In simulations where the flow field mesh deforms or undergoes local refinement / coarsening over time, after each mesh update, the S1 operation is re-executed for all particles. This involves quickly determining their "initial" element in the new mesh based on their currently recorded position using background mesh search or neighbor information, and then continuing the S2-S4 process for subsequent time steps. This extension ensures the continued effectiveness of the method in complex dynamic scenarios such as fluid-structure interaction and large deformation flows.

[0021] In this embodiment, a test was conducted on a specific nozzle. The inlet gas and particle phase temperatures were both 555.6 K, and the total gas phase pressure was 1.034 MPa. The gas phase was air, and the particles were aluminum oxide particles with a density of 4004 kg / m³. 3 It has a specific heat capacity of 1380 J / (kg·K) and a particle diameter of 20 μm.

[0022] Figure 3 The computational grid of this embodiment is given. Figure 4 The calculated nozzle particle distribution is given. Figure 5 The results of calculations and experiments along the nozzle axis are compared to verify the effectiveness of the present invention.

[0023] According to embodiments of the present invention, the localization and tracking of particle motion in complex flow fields can be achieved efficiently and accurately. This method intelligently determines whether a particle has crossed a cell boundary by calculating the shortest time for a particle to reach each face of a grid cell and comparing it with the calculation step size. This avoids the huge computational overhead of traditional global search and significantly improves the computational efficiency of two-phase flow simulation. Simultaneously, position updates based on rigorous geometric and kinematic formulas ensure the accuracy of particle trajectories. This scheme has a clear structure, high modularity, and is easy to integrate and apply, providing a reliable and practical technical means for high-fidelity numerical simulation of large-scale particle swarms.

[0024] Device Examples According to an embodiment of the present invention, a particle positioning device for Eulerian-Lagrange two-phase flow simulation is provided. Specifically, the particle positioning device for Eulerian-Lagrange two-phase flow simulation according to this embodiment includes: Initialize the module to obtain the initial particle position and its cell; The shortest time calculation module calculates the shortest time for the current particle position to reach each face within the cell. And record the corresponding face number; The calculation module is used to compare the shortest time for particles to reach each surface within the cell. With calculation time step Determine whether the particle is still within the unit cell; The recording module is used to record the position of the particles and the cell in which they are located.

[0025] The initial particle positions in the initialization module are distributed at the engine inlet boundary and are uniformly injected into the flow field from the center of each cell on the inlet grid surface according to the gas phase velocity.

[0026] The shortest time calculation module is specifically used for: Calculate the time it takes for a particle to reach the cell surface: ; In the formula , , These represent the velocities of the particle in the three directions (x, y, z) of a Cartesian coordinate system. , , These represent the positions of the particles. , , , Let the coefficients of the following equation of the plane of the triangle satisfy: ; After obtaining the times for all faces, select the smallest time that has physical significance. Record the face number corresponding to the minimum time. .

[0027] The calculation module is specifically used for: when If the particle is still in the original unit, particle tracking ends. When, the particles pass through Proceed to the next unit, and repeat the shortest time calculation module and calculation module for the new unit until the requirement is met. .

[0028] The recording module is specifically used for: The particle position was recorded as follows: ; ; ; The cell containing the particle is the last cell tracked by the calculation module.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A particle localization method for Eulerian-Lagrange two-phase flow simulation, characterized in that... include: S1. Obtain the initial particle position and its cell; S2. Calculate the shortest time for the current particle position to reach each surface within the cell. And record the corresponding face number; S3. Compare the shortest times for particles to reach each surface within the cell. With calculation time step Determine whether the particle is still within the unit cell; S4. Record the particle location and its cell.

2. The method according to claim 1, characterized in that, The initial particle positions are distributed at the engine inlet boundary and are uniformly injected into the flow field from the center of each cell on the inlet grid surface according to the gas phase velocity.

3. The method according to claim 1, characterized in that, The calculation of the shortest time for the current particle position to reach each face within the cell specifically includes: Calculate the time it takes for a particle to reach the cell surface: ； In the formula , , These represent the velocities of the particle in the three directions (x, y, z) of a Cartesian coordinate system. , , These represent the positions of the particles. , , , Let the coefficients of the following equation of the plane of a triangle satisfy: ； After obtaining the times for all faces, select the smallest time that has physical significance. Record the face number corresponding to the minimum time. .

4. The method according to claim 1, characterized in that, S3 specifically includes: when If the particle is still in the original unit, particle tracking ends. When, the particles pass through Proceed to the next unit, and repeat steps S2 and S3 for the new unit until the condition is met. .

5. The method according to claim 3, characterized in that, S4 specifically includes: The particle location is: ； ； ； The cell containing the particle is the last cell tracked by S3.

6. A particle positioning device for Eulerian-Lagrange two-phase flow simulation, characterized in that... include: Initialize the module to obtain the initial particle position and its cell; The shortest time calculation module calculates the shortest time for the current particle position to reach each face within the cell. And record the corresponding face number; The calculation module is used to compare the shortest time for particles to reach each surface within the cell. With calculation time step Determine whether the particle is still within the unit cell; The recording module is used to record the position of the particles and the cell in which they are located.

7. The apparatus according to claim 6, characterized in that, The initial particle positions in the initialization module are distributed at the engine inlet boundary and are uniformly injected into the flow field from the center of each cell on the inlet grid surface according to the gas phase velocity.

8. The apparatus according to claim 6, characterized in that, The shortest time calculation module is specifically used for: Calculate the time it takes for a particle to reach the cell surface: ； In the formula , , These represent the velocities of the particle in the three directions (x, y, z) of a Cartesian coordinate system. , , These represent the positions of the particles. , , , Let the coefficients of the following equation of the plane of a triangle satisfy: ； After obtaining the times for all faces, select the smallest time that has physical significance. Record the face number corresponding to the minimum time. .

9. The apparatus according to claim 6, characterized in that, The calculation module is specifically used for: when If the particle is still in the original unit, particle tracking ends. When, the particles pass through Proceed to the next unit, and repeat the shortest time calculation module and calculation module for the new unit until the requirement is met. .

10. The apparatus according to claim 8, characterized in that, The recording module is specifically used for: The particle position was recorded as follows: ； ； ； The cell containing the particle is the last cell tracked by the calculation module.

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