1. A high-precision numerical simulation method based on Riemann problem accurate solution is characterized by comprising the following steps: the method for realizing the high-precision numerical simulation of the multi-substance interaction based on the Riemann problem accurate solution comprises the following steps:

step 1: determining a calculation region according to an actual problem, establishing an Euler rectangular coordinate system, dividing the x direction of the calculation region into m grids, dividing the y direction into n grids, dividing the z direction into l grids, and counting m × n × l grids;

step 2: defining a level set level-set function in a calculation region, distinguishing the initial state interface position of each substance, defining the initial physical quantity, a material state equation and a conservation type Euler control equation set of each substance according to the region divided by the level-set, and simultaneously setting boundary conditions;

the conservation-oriented Euler control equation system is as follows:

wherein the content of the first and second substances,

e is the total energy of unit mass of the material, E is the specific internal energy of the material,g is gravity acceleration, u, v and w are velocities in x, y and z directions respectively, p is pressure of the material, and rho is density of the material;

and step 3: calculating a time step by taking a calculation parameter CFL;

and 4, step 4: solving normal vectors of material interfaces in each area, and establishing a Riemann problem along the normal direction of the material interfaces according to the properties of materials on two sides of the interfaces;

and 5: accurately solving a method MERS by utilizing a multi-substance Riemann problem to obtain a physical state after substances on two sides of an interface interact;

step 6: according to different properties of substances on two sides of the interface, different GFM methods are adopted to obtain the physical state of the grid near the multi-substance interaction interface;

and 7: respectively carrying out space dispersion and time dispersion on the calculation area of each substance by adopting a high-precision finite difference WENO format and a TVD Runge-Kutta format to obtain tⁿ⁺¹The physical state of each material region at the moment;

and 8: a level-set function is advanced to obtain tⁿ⁺¹Level-Set function of each material region at time, i.e. tⁿ⁺¹The position of each material interface at the moment;

and step 9: t obtained according to step 8ⁿ⁺¹At the moment, the position of each material interface is determined, and t is obtained in the step 7ⁿ⁺¹Integrating the physical states of the material regions at the moment to obtain tⁿ⁺¹The physical state of the whole calculation area is obtained at the moment;

step 10: judging the current calculation time tⁿ⁺¹Whether the set end time t is exceeded^endIf t isⁿ⁺¹＞t^endIf so, ending the numerical calculation and outputting the physical state of the whole calculation area at the moment; if tⁿ⁺¹＜t^endThen, go back to step 3 to continue the multi-object processingAnd (3) performing high-precision numerical simulation on mass interaction.

2. The high-precision numerical simulation method based on the Riemann problem accurate solution according to claim 1, wherein: further comprising the step 11: the Riemann-based problem accurate solving is carried out by utilizing the steps 1 to 10, the high-precision numerical simulation of the multi-substance interaction is realized, the precision of the numerical simulation of the multi-substance interaction process is improved, the goodness of fit with an experimental result is improved, the prediction precision of the multi-substance interaction process can be improved, and further the engineering technical problem related to the field of the multi-substance interaction is solved;

the fields of multi-substance interaction comprise high-speed/ultrahigh-speed penetration and protection, aerospace navigation and mechanical engineering fields.

3. The high-precision numerical simulation method based on the Riemann problem accurate solution according to claim 2, wherein: predicting a multi-substance interaction process in the engineering field, wherein the multi-substance interaction process comprises explosive air explosion, near-ground explosion, deep water explosion, water surface explosion, energy-gathering jet flow, ultra-high speed collision problem, supernova explosion and Rayleigh Taylor instability problem.

4. A high accuracy numerical simulation method based on the precision solving of the riemann problem as claimed in claim 1, 2 or 3 wherein: step 5 the method is realized by the following steps,

step 5.1: along the normal direction, respectively representing substances on two sides of the interface by L and R, and respectively representing substances on two sides of the interface after interaction by L and R;

step 5.2: according to the physical state of the substances on the two sides of the interface, the speed of the wave generated by the interaction of the substances on the two sides of the interface and the interface speed are preliminarily calculated, and the formula is as follows:

wherein the content of the first and second substances,s_L、s_Rrespectively the velocity of the two side waves, s_cIs the interface velocity, u_L、u_RRespectively the velocity of the two side materials, p_L、ρ_RDensity of bilateral substances, p_L、p_RRespectively the pressure of the substances on both sides;

step 5.3: and (3) preliminarily calculating the physical state of the two sides of the interface after the substances interact according to the wave velocity obtained in the step 5.2 by utilizing the R-H relation of the shock wave, wherein the general formula is as follows:

wherein the content of the first and second substances,respectively the density of substances on two sides of the interface after interaction,respectively the speeds of the substances on the two sides of the interface after the interaction,respectively the specific energy of the substances on two sides of the interface after the interaction,respectively, the pressure of the substances on both sides of the interface after interaction, E_L、E_RThe specific energy of the substances on both sides;

step 5.4: judging the type of waves generated by the interaction of substances on two sides of the interface according to the entropy condition, wherein the type comprises shock waves and sparse waves;

step 5.5: according to the judgment of the wave types at the two sides in the step 5.4, different calculation methods are adopted according to different wave types to obtain the wave velocity s corresponding to the wave velocity_L、s_RThe substances on the two sides of the interface are in an accurate physical state after interaction;

step 5.5a: for shock wave, the relation of R-H of shock wave is used to solve the wave speed s_LOr s_RThe physical state of one side after the interaction of substances on the two sides of the interface;

step 5.5 b: for sparse waves, the wave velocity s is obtained by utilizing the relation of sparse waves_LOr s_RThe physical state of one side after the interaction of substances on the two sides of the interface;

step 5.6: correcting the speed of the wave generated by the interaction of the substances on the two sides of the interface according to the physical state obtained in the step 5.5 after the substances on the two sides of the interface interact with each other;

step 5.7: and (5.5) repeating the steps 5.5-5.6 until the precision requirement is met, and obtaining the precise wave velocity and the interface speed of the wave generated by the interaction of the substances on the two sides of the interface and the precise physical state of the substances on the two sides of the interface corresponding to the precise wave velocity after the interaction.

5. The high-precision numerical simulation method based on the Riemann problem accurate solution according to claim 4, wherein: step 5.5a said solving out wave velocity s_LOr s_RThe method for the physical state of the single side after the interaction of the substances on the two sides of the interface comprises the following steps: by adopting a Newton iteration method, the formula is as follows,

wherein the content of the first and second substances,or

Or

U_L、U_RRespectively are the conservation variables of the substances on the two sides,as a conservation variable of the substances on both sides of the interface after interaction, F_L、F_RRespectively are the conservation variables of the substances on the two sides,is the conservation variable of substances on two sides of the interface after interaction, and further obtains the wave velocity s_LOr s_RThe physical state of the single side after the interaction of the substances on both sides of the interface.

6. The high-precision numerical simulation method based on the Riemannian problem accurate solution according to claim 5, wherein: the specific implementation of step 5.5b is,

wherein the content of the first and second substances,or

Or

To obtainWave velocity of s_LOr s_RThe physical state of the single side after the interaction of the substances on both sides of the interface.

7. The high-precision numerical simulation method based on the Riemann problem accurate solution according to claim 6, wherein: the specific implementation method of the step 5.6 comprises the following steps: newton iteration is adopted, and the formula is as follows,

wherein the content of the first and second substances, calculating by adopting a perturbation method:

8. the high-precision numerical simulation method based on the Riemann problem accurate solution according to claim 7, wherein: step 6 is realized by the method that,

adopting an RGFM method aiming at the interaction between the fluid and adopting a WGFM method aiming at the interaction between the fluid and the rigid body; and then determining the physical state of the multilayer grid near each material interface according to the precise physical state obtained in the step 5 after the materials on the two sides of the interface interact, and calculating other materials in the same way to obtain the physical state of the multilayer grid near each material interface.

Background

The detonation of the explosive is accompanied by a violent chemical reaction that forms an explosive shock wave that propagates outward and produces a large amount of explosive gas product. The research on the propagation rule of the explosion shock wave plays an important role in preventing the structure from being damaged by the explosion shock wave.

The research on the explosive air explosion mainly comprises theoretical derivation, numerical simulation and experimental research. The theoretical derivation has certain guiding significance in early research, but the explosion has the characteristics of high temperature, high pressure, high speed and the like, is a typical complex nonlinear problem, causes great difficulty in theoretical derivation, simplifies the theoretical research, and generally has no universality and a narrow application range. The experimental study is the most direct and accurate study method, but the study period is long, the expenditure is high, the difficulty of carrying out the large equivalent prototype test is high, uncertain factors often exist in the test, the repeatability is poor, and the measurement and observation of the explosion test are also difficult.

With the development of computers, numerical simulation has become an important tool for studying explosion and impact problems. The numerical simulation has the advantages of perfect theory, high efficiency, strong adaptability, simple operation and the like, and compared with experimental research, the numerical simulation can greatly shorten the research period and reduce the research cost. The numerical simulation has the significance of replacing experiments to a certain extent, so that the experiment cost and the experiment risk are reduced, and meanwhile, the data with the error of the experiment result within a controllable range is obtained, and the precision of the numerical simulation result is very important. The existing numerical simulation technology usually adopts a virtual fluid method (GFM) and a method for solving a Riemannian problem to obtain an interface state combination when processing a multi-substance interaction problem, and the precision of the Riemannian problem solving directly influences the precision of the interface state, so that a numerical simulation result is greatly influenced. The multi-substance complex state equation Riemannian problem is generally solved by adopting an approximate solving method, the multi-substance Riemannian problem is simplified into a double-wave structure by approximating the wave types, such as a double-shockwave approximate Riemannian problem solving method (TSRS), a double sparse wave Riemannian problem solving method (TRRS) and the like, an HLL method is obtained by derivation, and on the basis of the HLL multi-substance Riemannian solving method, consideration on contact discontinuity is added, and the HLLC method is obtained. Although the multi-substance Riemann problem solving method has wide application, the method fails to judge the type of the wave generated by the interaction of the multi-substance, is an approximate Riemann solving method, has large solving error, causes low interface state precision and further causes reduction of numerical simulation result precision, and needs to be made up urgently, so that the method has important engineering value and application significance.

Disclosure of Invention

Aiming at the problems that the Riemann problem in the existing multi-substance interaction numerical simulation method is solved by an approximation method, the interface state error is large, the calculation result precision is influenced and the like, the invention discloses a multi-substance interaction high-precision numerical simulation method based on the Riemann problem precision solving, which aims to solve the technical problems that: the method has the advantages that the Riemann problem of any state equation is solved accurately, the accurate interface state of the multi-substance interaction is obtained, the accuracy of numerical calculation results in the multi-substance interaction process is improved, the prediction accuracy of the multi-substance interaction process is improved, and further the engineering technical problems related to the field of the multi-substance interaction are solved.

The multi-material interaction field comprises the fields of high-speed/ultrahigh-speed warhead penetration and protection, explosion and structure interaction, aerospace and mechanical engineering.

The purpose of the invention is realized by the following technical scheme.

The invention discloses a high-precision numerical simulation method based on Riemann problem accurate solving, which is a high-precision numerical simulation method combining a multi-substance arbitrary state equation Riemann problem accurate solving method and a virtual fluid method (GFM), and comprises a real virtual fluid method (RGFM), a wall surface virtual fluid method (WGFM), a high-precision numerical simulation method simultaneously coupled with a weighted essentially non-oscillation (WENO) finite difference method and a Level-Set method (Level-Set), so that the precision of interface state solving can be improved, and errors of numerical simulation results and experimental results can be reduced. The WENO finite difference format converts flux solution in an Euler equation into high-precision discrete solution by selecting lattice points of a space template, so that numerical value oscillation is reduced while precision is ensured; the Level-Set method can effectively track the position change of the complex multi-medium interface; the RGFM method processes the interface state by setting a virtual flow field, and keeps the pressure and speed continuity of the interface; the WGFM method realizes the multi-substance coupling numerical simulation of the fluid and the rigid body by setting a virtual wall surface interface state at the interface of the fluid and the rigid body; the method for accurately solving the Riemann problem of the multi-substance arbitrary state equation can obtain the accurate interface state of the interaction of the multi-substance by accurately solving the Riemann problem of the arbitrary state equation, and improves the numerical simulation precision. The invention can effectively realize high-precision numerical solution on the problem of multi-substance interaction.

The invention discloses a high-precision numerical simulation method based on Riemann problem accurate solution, which realizes multi-substance interaction high-precision numerical simulation based on Riemann problem accurate solution and comprises the following steps:

step 1: determining a calculation region according to an actual problem, establishing an Euler rectangular coordinate system, dividing the x direction of the calculation region into m grids, dividing the y direction into n grids, dividing the z direction into l grids, and counting m × n × l grids.

Step 2: defining a level set level-set function in the calculation area for distinguishing the initial state interface position of each substance, defining the initial physical quantity, the material state equation and the conservation type Euler control equation set of each substance according to the area divided by the level-set, and simultaneously setting boundary conditions.

The conservation-oriented Euler control equation system is as follows:

wherein the content of the first and second substances,

e is the total energy of unit mass of the material, E is the specific internal energy of the material,g is the gravity acceleration, u, v, w are the velocities in the x, y, z directions, respectively, p is the pressure of the material, and ρ is the density of the material.

And step 3: and taking a calculation parameter CFL to calculate the time step.

And 4, step 4: solving the normal vector of the material interface in each area, and establishing a Riemann problem along the normal direction of the material interface according to the properties of the materials on two sides of the interface.

And 5: and (4) obtaining the physical state of the two sides of the interface after the substances interact by using a multi-substance Riemann problem accurate solving method MERS.

Step 5.1: along the normal direction, L and R denote the substances on both sides of the interface, and L and R denote the substances on both sides of the interface after the interaction, respectively.

Step 5.2: according to the physical state of the substances on the two sides of the interface, the speed of the wave generated by the interaction of the substances on the two sides of the interface and the interface speed are preliminarily calculated, and the formula is as follows:

wherein s is_L、s_RRespectively the velocity of the two side waves, s_cIs the interface velocity, u_L、u_RRespectively the velocity of the two side materials, p_L、ρ_RDensity of bilateral substances, p_L、p_RRespectively the pressure of the two side materials.

Step 5.3: and (3) preliminarily calculating the physical state of the two sides of the interface after the substances interact according to the wave velocity obtained in the step 5.2 by utilizing the R-H relation of the shock wave, wherein the general formula is as follows:

where ρ is_L*、ρ_R*Respectively the density of the substances on both sides of the interface after interaction, u_L*、u_R*Respectively the velocities of the substances on both sides of the interface after interaction, E_L*、E_R*Respectively, specific energy of substances on both sides of the interface after interaction, p_L*、p_R*Respectively, the pressure of the substances on both sides of the interface after interaction, E_L、E_RThe specific energy of the two side materials is respectively.

Step 5.4: and judging the types of waves generated by the interaction of substances on two sides of the interface according to the entropy condition, wherein the types comprise shock waves and rarefaction waves.

Step 5.5: according to the judgment of the wave types at the two sides in the step 5.4, different calculation methods are adopted according to different wave types to obtain the wave velocity s corresponding to the wave velocity_L、s_RThe precise physical state of the material on both sides of the interface after interaction.

Step 5.5 a: for shock wave, the relation of R-H of shock wave is used to solve the wave speed s_LOr s_RThe physical state of the single side after the interaction of the substances on both sides of the interface.

Step 5.5a said solving out wave velocity s_LOr s_RThe method for the physical state of the single side after the interaction of the substances on the two sides of the interface comprises the following steps: adopting a Newton iteration method, wherein the formula is as follows:

orWherein R is_s＝F_L-F_L*-s_L(U_L-U_L*) Or R_s＝F_R-F_R*-s_R(U_R-U_R*)

OrU_L、U_RRespectively, the conservation variables of the two side substances, U_L*、U_R*As a conservation variable of the substances on both sides of the interface after interaction, F_L、F_RRespectively, the conservation variables of the two side substances, F_L*、F_R*Is the conservation variable of substances on two sides of the interface after interaction, and further obtains the wave velocity s_LOr s_RThe physical state of the single side after the interaction of the substances on both sides of the interface.

Step 5.5 b: for sparse waves, the wave velocity s is obtained by utilizing the relation of sparse waves_LOr s_RThe physical state of the single side after the interaction of the substances on both sides of the interface.

The specific implementation method of the step 5.5b is as follows:

wherein u is_L-c_L≤ξ≤u_L*-c_L*Or u_R+c_R≤ξ≤u_R*+c_R*

Or

Obtaining a wave velocity of s_LOr s_RThe physical state of the single side after the interaction of the substances on both sides of the interface.

Step 5.6: and 5.5, correcting the speed of the wave generated by the interaction of the substances on the two sides of the interface according to the physical state obtained in the step 5.5 after the substances on the two sides of the interface interact.

The specific implementation method of the step 5.6 comprises the following steps: newton iteration is adopted, and the formula is as follows:

wherein the content of the first and second substances,calculating by adopting a perturbation method:

step 5.7: and (5.5) repeating the steps 5.5-5.6 until the precision requirement is met, and obtaining the precise wave velocity and the interface speed of the wave generated by the interaction of the substances on the two sides of the interface and the precise physical state of the substances on the two sides of the interface corresponding to the precise wave velocity after the interaction.

Step 6: and obtaining the physical state of the grid near the multi-substance interaction interface by adopting different GFM methods according to different properties of substances on two sides of the interface.

Adopting an RGFM method aiming at the interaction between the fluid and adopting a WGFM method aiming at the interaction between the fluid and the rigid body; and then determining the physical state of the multilayer grid near each material interface according to the precise physical state obtained in the step 5 after the materials on the two sides of the interface interact, and calculating other materials in the same way to obtain the physical state of the multilayer grid near each material interface.

And 7: respectively carrying out space dispersion and time dispersion on the calculation area of each substance by adopting a high-precision finite difference WENO format and a TVD Runge-Kutta format to obtain tⁿ⁺¹The physical state of each material region at that time.

And 8: a level-set function is advanced to obtain tⁿ⁺¹Level-Set function of each material region at time, i.e. tⁿ⁺¹The position of the interface of each substance at the moment.

And step 9: t obtained according to step 8ⁿ⁺¹At the moment, the position of each material interface is determined, and t is obtained in the step 7ⁿ⁺¹Integrating the physical states of the material regions at the moment to obtain tⁿ⁺¹The physical state of the entire computing area at the moment.

Step 10: judging the current calculation time tⁿ⁺¹Whether the end of the setting is exceededTime t^endIf t isⁿ⁺¹＞t^endIf so, ending the numerical calculation and outputting the physical state of the whole calculation area at the moment; if tⁿ⁺¹＜t^endAnd returning to the step 3, and continuing to perform the multi-substance interaction high-precision numerical simulation.

Further comprising the step 11: the Riemann-based problem accurate solving is carried out by utilizing the steps 1 to 10, the high-precision numerical simulation of the multi-substance interaction is realized, the precision of the numerical simulation of the multi-substance interaction process is improved, the goodness of fit with an experimental result is improved, the prediction precision of the multi-substance interaction process can be improved, and further the related engineering technical problem in the field of the multi-substance interaction is solved.

The fields of multi-substance interaction comprise high-speed/ultrahigh-speed penetration and protection, aerospace navigation and mechanical engineering fields.

Predicting a multi-substance interaction process in the engineering field, wherein the multi-substance interaction process comprises explosive air explosion, near-ground explosion, deep water explosion, water surface explosion, energy-gathering jet flow, ultra-high speed collision problem, supernova explosion and Rayleigh Taylor instability problem.

Has the advantages that:

1. the high-precision numerical value simulation method based on the Riemann problem accurate solution can improve the precision of numerical calculation results in the multi-substance interaction process, improve the goodness of fit with experimental results, and further accurately predict the multi-substance interaction problems in the engineering field such as explosive air explosion, near-ground explosion, deep water explosion, water surface explosion, energy-gathering jet flow, ultra-high speed collision problem, supernova explosion, Rayleigh Taylor instability problem and the like.

2. The invention discloses a high-precision numerical simulation method based on Riemann problem accurate solution, which is characterized in that a WENO format is adopted to disperse a space derivative term of an Euler equation, and a TVD Runge-Kutta format is adopted to disperse a time derivative term of the Euler equation.

3. The invention discloses a high-precision numerical simulation method based on Riemann problem accurate solution, which adopts a multi-substance arbitrary state equation Riemann problem accurate solution method combined with RGFM and WGFM methods according to different substance properties at two sides of an interface to process the strong discontinuity problem of multi-substance interface interaction and has the discontinuity characteristic of high resolution of a substance interface; compared with the classical GFM method, the method can effectively process various complex state equations, can effectively improve the precision of processing the interaction of multiple substances, can effectively inhibit the non-physical oscillation phenomenon generated at the interface when the Euler equation is solved, and can ensure the stable operation of the numerical simulation process.

4. The invention discloses a high-precision numerical simulation method based on Riemann problem accurate solution, which adopts a Riemann problem accurate solution method of a multi-substance arbitrary state equation, can accurately process various complex state equations compared with the traditional multi-substance approximate Riemann solution method, can obtain accurate physical states of substances on two sides of a multi-substance interaction interface, improves the accuracy of multi-substance interaction calculation, reduces errors with experimental results, and has obvious advantages in processing the multi-substance complex state equation interaction problem in the engineering field.

Drawings

FIG. 1 is a structural diagram of a Riemannian problem and a wave system, wherein a is a schematic diagram of the Riemannian problem, and b is a schematic diagram of the wave system structure of the Riemannian problem;

FIG. 2 is a schematic diagram of entropy conditional decision wave types;

FIG. 3 is a schematic diagram of precision Riemann's solution in conjunction with RGFM;

FIG. 4 is a schematic diagram of precision Riemann's solution in conjunction with WGFM;

FIG. 5 is a schematic view of an initial geometric model of example 1;

FIG. 6 is a blast protected structure of example 1;

FIG. 7 is a schematic view of the explosion shock wave pressure monitoring points in example 1;

FIG. 8 is a pressure contour plot at different times of the detonation flow field of example 1;

FIG. 9 is a cloud of numerically simulated pressures for interaction of the blast shock wave with the containment structure of example 1;

FIG. 10 is a comparison of the numerical simulation of the explosion shock wave pressure monitoring points and the test pressure curves of example 1;

fig. 11 is a flowchart of an embodiment 1 disclosing a high-precision numerical simulation method for multi-substance interaction based on the riemann problem accurate solution.

Detailed Description

Example 1:

for better illustrating the objects and advantages of the present invention, the present invention will be further described with reference to the accompanying drawings and examples.

The embodiment is applied to the interaction calculation example of explosive blast and protective structures.

The initial geometric model in the calculation example disclosed in the embodiment is shown in the attached drawing (5), the shock wave protection structure and the pressure monitoring points are respectively shown in the attached drawings (6) and (7), the pressure isosurface maps of different moments of the explosion flow field are shown in the attached drawing (8), the numerical simulation pressure cloud map of the interaction between the explosion shock wave and the protection structure is shown in the attached drawing (9), and the comparison of the numerical simulation and the test shock wave pressure curve is shown in the attached drawing (10).

As shown in fig. 11, the embodiment discloses a high-precision numerical simulation method based on the precision solving of the riemann problem, and the specific implementation method is as follows:

step 1: according to the actual physical problem, a calculation area is determined to be 58m 22m 11m, an Euler rectangular coordinate system is established, the x direction of the calculation area is divided into 696 grids, the y direction is divided into 264 grids, the z direction is divided into 132 grids, and 24254208 grids are counted.

Step 2: as shown in attached drawings (5) and (6), the overall span and height of the protective structure are respectively 13m and 6.8m, the thickness of the main wall structure is 0.3m, the length of the main wall structure is 9m, the height of the main wall structure is 6.8m, the height of the supporting structure is 0.25m, the length of the supporting structure is 0.9m, the wing wall structure is L-shaped and is the same as the thickness and height of the main wall, the length of the wing wall structure is 2m, the length of a part of the wing wall perpendicular to the main wall surface is 1.05m, 1t TNT explosive is arranged at a position 45m away from the main wall surface, and according to the defined level-set function, the calculation area is divided into air, explosive and the protective structure. The values of the initial states of the air and the explosive and the parameters of the state equation are shown in the following table:

table 1:

according to the practical physical problem, a non-reflection boundary condition is set at the boundary so as to realize an infinite air domain.

And step 3: the CFL parameter takes 0.3 and calculates the time step.

Step 4, solving the normal vector of the material interface in each area by using a level-set function, wherein the solving formula is as follows:

step 4.2: and establishing the Riemann problem between the substances on the two sides of the interface along the normal direction of the substance interface according to the normal vector of the substance interface and the properties of the substances on the two sides of the interface.

Aiming at the interaction between the fluid and the fluid, a Riemann problem is established according to different physical states of the fluid on two sides of the interface along the normal direction of the interface; aiming at the interaction between the fluid and the solid, a wall Riemann problem is established according to the physical state of the fluid on one side of the interface along the normal direction of the interface.

And 5: solving the Riemann problem in the normal direction established in the step 4, firstly, preliminarily calculating the speed of the wave generated by the interaction of the substances on the two sides of the interface and the interface speed, and preliminarily calculating the physical state of the substances on the two sides of the interface after the interaction by utilizing the R-H relation of the shock wave; secondly, accurately judging the types of waves on two sides of the interface according to the entropy condition; then, different calculation methods are adopted according to different wave types on two sides of the interface, for shock waves, a shock wave R-H relation formula and a Newton iteration method are combined, for sparse waves, a sparse wave relation and a classical 4-order Runge Kutta method are combined, and a physical state corresponding to the wave speed obtained through preliminary calculation after the substances on the two sides of the interface interact is obtained; then, according to the contact interruption condition, Newton iteration is adopted to correct the wave speeds of the two sides of the interface; and finally, repeating the process until the precision requirement is met, and obtaining the precise speed of the wave generated by the interaction of the substances on the two sides of the interface, the interface speed and the precise physical state of the interacted substances on the two sides of the interface corresponding to the precise wave speed.

Step 6: and obtaining the physical state of the grid near the multi-substance interaction interface by adopting different GFM methods according to different properties of substances on two sides of the interface.

Adopting an RGFM method aiming at the interaction between the fluid and the fluid, adopting a WGFM method aiming at the interaction between the fluid and the rigid body, and then determining the physical state of the multilayer grid near each material interface according to the accurate physical state obtained in the step 5 after the materials on the two sides of the interface interact, wherein the method comprises the following specific steps:

when the material 1 is calculated, setting the calculation area of other materials as a virtual grid, wherein the information on the virtual grid is obtained by extending the accurate physical state after the interaction of the materials on the two sides of the interface obtained in the step 5, and the extension equation is as follows:

wherein, I represents physical quantities such as density, speed, pressure and the like, and n is a gradient direction vector of the point. The physical state of the multi-layer lattice in the vicinity of the interface of the substance 1 is thus obtained. And calculating other substances in the same way to obtain the physical state of the multilayer grid near each substance interface.

And 7: respectively carrying out space dispersion and time dispersion on the calculation area of each substance by adopting a high-precision finite difference WENO format and a TVD Runge-Kutta format to obtain tⁿ⁺¹The physical state of each material region at that time.

Step 7.1: preferably, a 5 th-order WENO format is adopted to discretize the spatial derivative term in the conservation-oriented Euler control equation set in the step 2.3, so as to obtain an ordinary differential equation set of the conservation variable relative to the time derivative:

step 7.2: preferably, the third-order TVD change-Kutta format is adopted to discretize the time derivative term of formula (14), the term at the right end of the equation (11) with the equal sign is denoted as L, and the propulsion time step is Δ t, so as to obtain the fully discrete format of the conservation-oriented euler control equation set:

step 7.3: repeating the steps 7.1-7.2, and performing space dispersion and time dispersion on the calculation region of each substance to obtain tⁿ⁺¹The physical state of each material region at that time.

And 8: adopting HJ-WENO format and TVD Runge-Kutta format to respectively disperse the spatial derivative term and the time derivative term of the Level-Set motion equation to obtain the fully-discrete format of the Level-Set motion equation,

and then obtain tⁿ⁺¹The Level-Set function of each material area at the moment.

And step 9: t obtained according to step 8ⁿ⁺¹At the moment, the position of each material interface is determined, and t is obtained in the step 7ⁿ⁺¹Integrating the physical states of the material regions at the moment to obtain tⁿ⁺¹The physical state of the entire computing area at the moment.

And then, carrying out steps 10 to 11 to obtain a numerical simulation result of the interaction between the explosive blast wave and the protective structure.

And (4) analyzing a calculation result:

the attached figure (8) is a pressure isosurface map of an explosion flow field at different moments, and it can be known from the figure that after an explosive explodes, explosion shock waves are transmitted in the air, after the explosion shock waves reach a protection structure, part of the explosion shock waves form reflection shock waves due to reflection of a main wall surface, and part of the explosion shock waves are influenced by reflection and diffraction of a wing wall structure. The attached drawing (9) is a pressure cloud chart of interaction between the explosion shock wave and the protective structure, and the reflection and diffraction of the explosion shock wave by the wing wall structure can be more obviously seen from the cloud chart, moreover, the Mach reflected wave formed by the explosion shock wave after reflection and diffraction on the wall surface can be seen in the area A, and the explosion shock wave transmitted through a communication structure such as a window can be seen in the area B. The figure (10) is a comparison of numerical simulation of the explosion shock wave pressure monitoring point and a test pressure curve, the comparison of the numerical simulation and the test result shows that the pressure curve has small peak value error and approximate overall trend, and the accuracy and the effectiveness of the numerical simulation technology are proved.

The above detailed description is intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above detailed description is only exemplary of the present invention and is not intended to limit the scope of the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.