KR101003456B1 - Post-processing method and computer-readable storage medium - Google Patents

Abstract

PURPOSE: A method for post-processing a floating analysis result and a computer readable storage media are provided to express the floating analysis result by reducing the computational complexity. CONSTITUTION: A structure is latticed to a plurality of 3D(Dimensional) lattice cells(S210). An intersection point or an intersection line is acquired by intersecting 3D orthogonal planes(S220). A lattice cell crossing with the surface of the structure is extracted(S230). A patch boundary on the edge of each boundary cell reflects each lattice cell(S240). The outside of the structure uses the patch boundary(S250).

Description

Post-processing method and computer-readable storage medium

The present invention relates to a post-processing method and a computer-readable storage medium, and to a post-processing method and a computer-readable storage medium which can express the flow analysis results in a realistic manner and at the same time reduce the amount of calculations.

For flow analysis, the structures are generally represented as Stereolithography Tessellation Language (STL) files, and pre-processing is performed on the structures represented as STL files. Pretreatment means, for example, a mesh generation process. After the preprocessing, the equations for flow analysis are calculated using the preprocessed information. For example, after preprocessing, the solver calculates a number of complex partial differential equations for flow numerical analysis. Based on the calculated information, the result is a post-process.

The finite difference method (FDM), the finite element method (FEM), and the finite volume method (FVM) may be used to generate the lattice. have.

In the case of using FDM, the structure is latticed using a hexahedron cell, and automatic lattice is possible at a relatively fast time. For example, when the structure shown in Fig. 1A is latticeed by the FDM method, as shown in Fig. 1B, the boundary surface of the boundary region is lattice-shaped. That is, since the boundary region of the structure, in particular, the boundary surface cannot be finely gridded, problems such as a decrease in convergence, loss of excessive pressure, and prediction error in the flow direction may occur. Using FEM or FVM can reduce the error of interpretation of FDM, but automatic lattice is impossible or time-consuming.

In addition, when the flow analysis is performed by the FDM method during the post-processing, and the result is displayed, the step shape is displayed, thereby reducing the accuracy and the realism. In other words, the result is derived in the shape of a staircase. In this case, accuracy and realism are poor, and errors are large.

An object of the present invention is to provide a post-treatment method that can express the flow analysis results in a realistic manner and at the same time reduce the amount of calculations so as to solve the above problems.

In order to solve the above problems, the present invention provides a computer-readable storage medium for storing a program for executing a post-method method which can express the flow analysis results in a realistic manner and at the same time reduce the amount of calculations for fast processing. There is this.

The object of the present invention is not limited to the above-mentioned object, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

A post-processing method according to an aspect of the present invention for achieving the above object is a method for post-processing a flow analysis result inside a structure gridized into a plurality of grid cells, a triangle of the structure of the grid cells Receiving information about boundary cells intersecting a triangular mesh, and body surfaces that are planes in which the triangular network intersects the boundary cell, calculating an amount of fluid filled in each of the grid cells; For a grid cell that intersects the fluid surface that separates the filled and unfilled portion from within the structure, the grid cell has the same reference value using the calculated amount of fluid in the grid cell. Calculating an iso surface, cutting out a portion of the isosurface outside the body surface of the boundary cell and indicating that the fluid is filled. It is.

Among the grid cells that do not intersect the fluid surface, the grid cells filled with the fluid may further include indicating that the rapeseed is filled using at least one of the boundary cell and the body surface. .

On the other hand, the step of calculating the amount of fluid for the grid point of each grid cell using the amount of the fluid for the center point obtained from the calculating step, the amount of fluid for the center point and the And extracting the position of the reference flow value using the amount of fluid with respect to a grid point, and connecting the extracted positions to calculate the equisurface.

The calculating of the amount of fluid with respect to the lattice point and the calculating of the isosurface may be performed only for the lattice cells that intersect the fluid surface.

In addition, the step of indicating that the portion of the back surface is cut off and the remaining surface inside the boundary cell and the body surface, the interior of the grid cell intersects with the fluid surface indicates that the fluid is filled through the color change Steps.

A computer readable storage medium according to another aspect of the present invention stores a program for executing the grid generating method described above.

Specific details of other embodiments are included in the detailed description and the drawings.

According to the present invention, it is possible to express the flow analysis results in a realistic manner and at the same time reduce the amount of calculation and to speed up processing.

1A and 1B are exemplary views for explaining a lattice method according to the prior art.
2 to 10 are flowcharts and conceptual diagrams illustrating a preprocessing method.
11 to 15 are conceptual views for explaining a post-processing method according to an embodiment of the present invention.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, “comprises” and / or “comprising” refers to the presence of one or more other components, steps, operations and / or elements. Or does not exclude additions.

Hereinafter, a post-processing method according to an embodiment of the present invention will be described, but the present invention is not limited to the order described below, but is only an example.

Before describing the post-treatment method according to an embodiment of the present invention, a process to be pre-processed for post-processing will be described first.

A pretreatment method will be described with reference to FIGS. 2 to 10. 2 is a flowchart illustrating a preprocessing method, and FIGS. 3 to 10 are conceptual diagrams for describing the preprocessing method.

Referring to FIG. 2, first, the structure is latticed into a plurality of three-dimensional lattice cells (S210). Here, the three-dimensional lattice cell may be a cube.

As shown in FIG. 3, when the structures are superimposed on a plurality of orthogonal grid lines in the x, y, and z axis directions (three-dimensional), the structure is a minimum unit formed by the grid lines as shown in FIG. The grid is gridized into three-dimensional grid cells. Here, the size and volume of the grating cell are adjustable.

On the other hand, the structure is represented by Streolithography Tessellation Language (STL), for example, as shown in Figure 5, by dividing the surface of the structure into a plurality of triangles, it can be represented by a triangular mesh (triangular mesh).

6, a plurality of orthogonal planes (x-axis plane, y-axis plane, z-axis plane) are generated in three dimensions so that the three-dimensional orthogonal planes cross the triangle network of the structure. Intersections or intersection lines (hereinafter referred to as section curves) generated by obtaining a signal are obtained (S220). Here, the three-dimensional orthogonal planes are planes orthogonal to the x, y, and z-axis directions (three-dimensional), and may be planes formed by extending each surface of the lattice cells, which are cubes illustrated in FIG. 3.

That is, when the plurality of three-dimensional orthogonal planes extend each surface of the plurality of lattice cells, the cross-sectional curve on each three-dimensional orthogonal plane may be the intersection or intersection of the planes of the plurality of lattice cells and the triangular network. have. And, with each cross-sectional curve, as shown in Fig. 7, a closed two-dimensional polygon (2D polygon) is obtained. Depending on the structure of the structure, two or more separate two-dimensional polygons may be obtained per section, and all two-dimensional polygons store edges of the two-dimensional polygon along the counterclockwise direction.

As shown in FIG. 7, the surface of the structure (the boundary that separates the inside and the outside of the structure) and the intersecting lattice cell (hereinafter referred to as the boundary cell) are extracted from the plurality of lattice cells. (S230). For example, among a plurality of grid cells, grid cells through which cross-sectional curves pass are classified as boundary cells.

Specifically, the types of the grid cells from the cross-sectional curves may be classified as follows.

1. boundary cell: lattice cell that intersects the boundary of the structure

2. Inside-cell: Lattice cell existing inside the structure corresponding to the flow field

3. Outside-cell: A cell outside the structure

As such, after classifying the boundary cells, the classification of the inside-cell and the outside-cell can be easily performed using a flood-fill algorithm.

On the other hand, classifying the boundary cells may be performed from the 2D scan-converting line algorithm of Bresenham using the aforementioned cross-sectional curves. As shown in FIG. 6, Brasonham's 2D scan-converting line follows cross-sectional curves generated from the intersection of three-dimensional orthogonal planes in the x, y and z axis directions with a triangular network. By performing the algorithm, the grid cells visited by the cross-sectional curves may be classified as boundary cells.

And, as shown in Figure 8, by reflecting the cross-sectional curves on the three-dimensional orthogonal plane in the x, y, z axis direction to each lattice cell, the boundary surface of the structure and each boundary cell is generated by the intersection of each boundary cell A patch boundary on each side is generated (S240).

That is, by using cross-sectional curves on the three-dimensional orthogonal plane, for each grid cell, portions of the cross-sectional curve passing through each side of the grid cell are extracted and combined. Since portions of the cross-sectional curves of the three-dimensional orthogonal planes in the x, y, and z axis directions are combined or fitted (reflected) for each lattice cell, a boundary is generated on one lattice cell six faces. The boundary created on the six faces of the grid cells of is called a patch boundary.

Then, the outside of the structure is cut at each boundary cell using the patch boundary (S250).

Specifically, by using a patch boundary, the cell surface consisting of the edge of the patch boundary and the boundary cell, and the body surface consisting of the patch boundary inside the boundary cell.

Specifically, the cell surface may be configured by cutting out some surfaces (two-dimensional clipping) from each surface of the grid cell using a patch boundary. As shown in (a), (b), (c) and (d) illustrated in FIG. 9, the cell surface may be configured by performing two-dimensional clipping according to the type of the patch boundary. On the other hand, since each plane is shared with adjacent grid cells, two-dimensional clipping is performed using a Weiler-Atherton Algorithm on three planes of each grid cell to prevent duplication of the two-dimensional clipping process. Can be done.

The body surface may be constructed by three-dimensionally cutting (three-dimensional clipping) a portion of the boundary cell using a patch boundary. Through this process, part of the surface of the structure is composed of the body surface.

In the case of (d) of FIG. 9, the patch boundary forms a closed curve on one surface of the boundary cell. As shown in FIG. 10, when a part of the structure does not pass through the lattice cell, for example, an edge exists inside. to be. In this case, three-dimensional clipping cannot be performed using only the patch boundary. In such a case, three-dimensional clipping may be performed using triangular network information (edge and vertex information, etc.) of a part of the structure inside the grid cell. That is, the outer surface of the patch boundary of the closed curve corresponding to the outside of the structure is cut out from one surface of the boundary cell, and the triangular network of the structure may be the body surface. Boundary cells can be referred to as cut cells because part of the boundary cells are cut along the surface of the structure (the triangular net for the structure).

This process cuts the outside of the structure in the boundary cell, calculates the area and volume of the remainder, and provides the calculated data to the solver for flow numerical analysis. And the data calculated by the solver is provided to the post-processor, and is post-processed according to the post-processing method according to an embodiment of the present invention described below.

A post-processing method according to an embodiment of the present invention will be described with reference to FIGS. 11 to 15. 11 to 15 are conceptual views illustrating a post-processing method according to an embodiment of the present invention.

First, the flow rate in each lattice cell of the structure is calculated. For example, the flow rate is calculated at the center point of each lattice cell (ie, the center of the cube cell in three dimensions). The flow rate may refer to the cell volume occupancy of the fluid. When the lattice cell is filled with fluid, as shown in FIG. 11, the analysis result is represented in a staircase shape.

For the lattice cells that do not intersect the surface of the fluid in the lattice cells, the fluid is filled using the information on the boundary cells of the structure obtained in the above-described pretreatment.

Specifically, for the lattice cell LC inside the structure that does not intersect the fluid surface in FIG. 11, as shown in FIG. 12, the color of the lattice cell is changed to indicate that the fluid is filled in the lattice cell. For the boundary cell BC, the color of the body surface, the cell surface, and / or the boundary cell is changed to indicate that the fluid is filled in the structure of the boundary cell. Thus, it can be realistically indicated that the fluid is filled in the shape of the structure.

On the other hand, for the grating cells that intersect the surface of the fluid in Figure 11, Iso surface having the same flow rate of the same reference value (Iso-value) is calculated, information about the calculated isosurface and the boundary cell To indicate that the fluid is filled.

Specifically, referring to FIG. 13 in which the portion S of FIG. 11 is enlarged, an equal surface is calculated for the grid cell intersecting with the fluid surface. For example, the flow rate is 0.3 at the center point C1 of the first lattice cell, the flow rate is 0.0 at the center point C2 of the second lattice cell, the flow rate is 0.0 at the center point C3 of the third lattice cell, and the flow rate is at the center point C4 of the fourth lattice cell. 0.95, the flow rate is 0.6 at the center point C5 of the fifth lattice cell, the flow rate is 0.0 at the center point C6 of the sixth lattice cell, the flow rate is 1.0 at the center point C7 of the seventh lattice cell, and at the center point C8 of the eighth lattice cell The flow rate is 0.3, and the flow rate is 0.0 at the center point C9 of the ninth lattice cell. Then, the flow rate of the grid point of each grid cell is calculated using the flow rate information of the center points C1 to C9 of each grid cell. For example, the flow rate of the grid point A2 may be an average value of the flow rates of the center points C1, C2, C4 and C5 of each cell. That is, the flow rate of the grid point A2 is (0.3 + 0.0 + 0.95 + 0.6) /4=0.46. In this way, the flow rates to the grid points A1 to A5 are calculated. In this embodiment, the flow rate of each lattice point is calculated by averaging the flow rate of each center point, but the present invention is not limited thereto, and may be calculated by other equations or methods.

Next, the position P1 to P4 of the reference flow rate value (Iso-value) is extracted using the flow rate information of the center points C1 to C9 and the grid point A1 to A5 flow rate information of each lattice cell. Here, the reference flow rate is a value that can be variably set by the user. For example, when 0.5 is used as an example, the flow rate information of the center points C1 to C9 of each grid cell and the flow rate information of each grid point A1 to A5 are used. On a plurality of grid lines constituting each grid cell, a position having a reference flow rate value of 0.5 is extracted. That is, as shown in FIG. 13, positions P1, P2, P3, and P4, which are 0.5 on each lattice line, are extracted and P1, P2, P3, and P4 are followed to produce an isosurface. In FIG. 13, the fifth grating cell BC5 is shown in FIG. 14 in three dimensions. Here, the isosurface is off the outside of the structure (outside the surface of the structure). That is, the back surface is out of the body surface of the boundary cell.

Accordingly, as shown in FIG. 15, the portion where the body surface and the back surface intersect is extracted, and the part that leaves the body surface of the back surface is cut out by using the boundary cell information (information on the body surface) obtained in the pretreatment process. The remaining portion is shown as filled with fluid. For example, when the intersection occurs, the body surface may be cut into the plane (representative plane) of the body surface having the longest length of the surface line among the body surfaces, and the representative plane may be found and cut in the same manner with respect to the remaining body surfaces.

According to the post-processing method according to the embodiment of the present invention, since the flow analysis results are displayed using the body surface obtained in the pre-treatment process, it is possible to exhibit a realistic result. In addition, the processing speed is increased by calculating the post-processing of the isosurface only for the lattice cells that intersect the fluid surface, and displaying the flow analysis results without calculating the isosurface for the lattice cells that do not intersect the fluid surface.

On the other hand, the above-described post-processing method according to an embodiment of the present invention can be written in a program that can be executed in a computer, it can be implemented in a general-purpose digital computer to operate the program using a computer-readable storage medium.

In addition, the post-processing method according to the embodiment of the present invention described above may be recorded and / or stored in a computer-readable storage medium through various means. Computer-readable storage media include magnetic storage media (e.g., ROMs, floppy disks, hard disks, etc.), optical read media (e.g., CD-ROMs, DVDs, etc.) and carrier waves (e.g., transmission over the Internet). Storage media such as

Those skilled in the art will appreciate that the present invention can be embodied in other specific forms without changing the technical spirit or essential features of the present invention. For example, a program for realizing the control method of the present invention may be implemented in various forms such as a recording medium in which a program is recorded. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the claims and their equivalents should be construed as being included in the scope of the present invention.

Claims (6)

A method of post-processing an internal flow analysis result for a structure gridized into a plurality of grid cells,
Receiving information about boundary cells intersecting a triangular mesh of the structure among the grid cells, and body surfaces that are planes on which the triangular network intersects the boundary cell;
Calculating an amount of fluid filled in each of the grid cells; And
For a grid cell that intersects the fluid surface that separates the filled and unfilled portion from within the structure, the grid cell has the same reference value using the calculated amount of fluid in the grid cell. Calculating an iso surface, cutting out portions of the iso surface out of the body surface with the body surface as a boundary, and indicating that the fluid is filled;
The above step shows
And cutting off portions outside the body surface and indicating that the fluid is filled by changing the color inside the lattice cell that intersects the fluid surface with the remaining back surface and the body surface as a boundary.
Post-processing method of phosphorus flow analysis results. The method of claim 1,
Indicating that the fluid is filled by using at least one of the boundary cell and the body surface of the grid cells filled with the fluid among the grid cells that do not intersect the fluid surface.
Post-processing method of phosphorus flow analysis results. The method of claim 1, wherein the step
Calculating an amount of fluid at a grid point of each grid cell using the amount of fluid at a center point of the grid cell obtained from the calculating step;
Extracting the position of the reference flow value using the amount of fluid relative to the center point and the amount of fluid relative to the grid point, and connecting the extracted positions to calculate the equisurface
Post-processing method of phosphorus flow analysis results. The method of claim 3,
Calculating the amount of fluid with respect to the grid point, and calculating the equisurface
For grid cells intersecting the fluid surface only
Post-processing method of phosphorus flow analysis results. delete A computer-readable storage medium storing a program for executing the post-processing method according to any one of claims 1 to 4.

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