JPH05307590A - Space mesh generating device for numerical analysis and numerical analytical device - Google Patents

Abstract

PURPOSE:To automatically divide the space on the surface of the earth into meshes. CONSTITUTION:Two-dimensional contour data is inputted by a data input/output device 101 and a topographic information input part 104, and an analysis area defining part 105 and a two-dimensional mesh generating part 106 are used to generate two-dimensional meshes, and three-dimensional mesh data is automatically generated from them by a three-dimensional mesh generating part 107. Since three-dimensional meshes on the surface of the earth are automatically generated only with two-dimensional meshing operation after map information is inputted by the interactive system to a computer, the input data generation time for fluid analysis is considerably shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical analysis spatial mesh generator, and in particular, generates an analytical mesh for analyzing a spatially (three-dimensionally) distributed physical quantity using the finite element method. The present invention relates to a numerical analysis spatial mesh generation device and a numerical analysis device that are suitable for performing.

[0002]

2. Description of the Related Art As a method of generating a three-dimensional mesh for analysis using the finite element method, as shown in Japanese Patent Application Laid-Open No. 63-6671, there are three contours on a ground surface from contour data on a map. There is a method of creating three-dimensional mesh data, a method of using three-dimensional ground surface shape data proposed in JP-A-2-236782, etc. for various calculations.

[0003]

When analyzing a spatial physical quantity such as analysis of flow, temperature, movement / diffusion of pollutants, or air flow in a wide area such as lakes and oceans, when analyzing a spatial physical quantity, Not only the surface or the bottom of the sea / lake, but also the space above it needs to be three-dimensionally meshed. However, the above-mentioned conventional technique does not automatically generate a mesh in the upper space of a surface defined by a shape such as the ground surface, and thus has a problem that a great amount of labor is required to generate this mesh.

An object of the present invention is to provide a numerical analysis spatial mesh generator for automatically dividing the upper space such as the ground surface into meshes so that the above-mentioned work such as flow analysis can be performed easily. And to provide an analysis device.

[0005]

According to the present invention, a topographical information input means for inputting a ground surface height distribution on a two-dimensional topographical map defined by contour lines, and a two-dimensional topographical map input by the means. Analysis area definition means for extracting an area to be analyzed by the instruction information, two-dimensional mesh generation means for dividing the analysis area defined by the means into a two-dimensional mesh that is a two-dimensional small area, and A three-dimensional mesh generation means is provided for dividing each columnar space in the height direction of the two-dimensional mesh defined by the means into a three-dimensional mesh which is a three-dimensional small area having a size corresponding to the instruction information. Further, the present invention provides a concrete method for each of the above means. Furthermore, it was decided to analyze the movement of the flow, temperature, substances, etc. inside the space above the surface of the earth using this generated mesh.

[0006]

The operator only needs to perform a simple operation such as specifying the analysis area, the number of divisions, or the division width, and the three-dimensional mesh data is automatically generated according to the instruction information obtained by receiving the instruction. Will be easy to analyze.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention. A data input / output device 101 through which an operator interactively inputs data and input data for analysis (topographic data, analysis area data, two-dimensional data) from topographic information. Mesh data, 3
Preprocessor 102 for creating three-dimensional mesh data)
And a database 103 that stores the input data for analysis created by the preprocessor 102. Further, the preprocessor 102 includes a topographic information input unit 104, an analysis region definition unit 105, a two-dimensional mesh generation unit 106, and a three-dimensional mesh generation unit 107, and each processing unit receives data from an instruction from the data input / output device 101. Conversion process, display on the display, and data access to the database.

Next, a general procedure for creating analysis input data using this system will be described. First, the operator
Using the data input device 101 such as a digitizer, the contour lines and the height of the map are input as the instruction information. The input contour lines (polygonal lines) are converted into two-dimensional graphic data in the topographic information input unit 104. On the other hand, the height information of contour lines is described as attribute data of polygonal lines representing contour lines. FIG. 2 is an example of the two-dimensional data created here, and the closed polygonal lines L _{1 to} L ₄ mean different heights. It is a contour line. Next, in the analysis area definition unit 105, the operator designates an analysis area for the two-dimensional figure input by the terrain information input unit 104, and the two-dimensional surface (composed of one outer loop and several hole loops) Defined surface area). FIG. 3 shows this example. In the analysis area definition unit 105, the inlet, outlet, and
Input analysis conditions such as walls to the boundary line of the two-dimensional surface,
Describe as the attribute data of the line that constitutes the boundary line. In the two-dimensional mesh generation unit 106, the analysis area definition unit 1 described above is used.
The analysis area defined in 05 is divided into two-dimensional finite elements,
Two-dimensional mesh data as shown in FIG. 4 is created.
Finally, in the three-dimensional mesh generation unit 107, the division information (division number and division width) in the height direction input by the operator,
A three-dimensional mesh is automatically generated from the two-dimensional mesh data generated by the two-dimensional mesh generation unit 106 and the height data of the contour lines input by the terrain information input unit 104. Figure 5
6 and 6 are examples of the three-dimensional mesh created here. (This is an example of printing by a printer, and each line in the figure is notched due to the resolution of the printer. There is no such notch originally.) In addition, here, when generating a three-dimensional mesh, a two-dimensional surface is generated. At the same time, the processing for converting the analysis condition data defined for the boundary line of the above into the analysis condition data for the three-dimensional mesh is performed. Finally, the three-dimensional mesh data and the analysis condition data are passed to the analysis unit 110 as analysis input data, and the analysis calculation is executed.

Next, the details of the processing units 104 to 107 will be described. In the terrain information input unit 104, first, the scale factor of the map is input, and the conversion factor between the size on the map and the actual size created inside the computer is set. Then, the operator uses the data input device 101 such as a digitizer to input a series of points along the contour lines on the map, and the polygonal lines connecting the series of points are converted into actual dimensions by the conversion magnification to calculate two-dimensional graphic data. To generate in.

The analysis area definition unit 105 sets an analysis area. The analysis region is a region sandwiched between adjacent closed loops as seen in the example of FIG. 2 and is a region between L ₁ and L ₂ (see FIG. 3).
E ₁ ), the region between L ₂ and L ₃ (E _{2 in} FIG. 3), the region between L ₃ and L ₄ (E _{3 in} FIG. ₃ ), the internal region of L ₃ (FIG. 3).
E ₄ ) of the four areas. Obtain the analysis area in the order of E ₁ → E ₂ → E ₃ → E ₄ . For example, in order to obtain the E ₁ area, first, the operator designates a part (line segment) L ₁₁ of the polygonal line L ₁ which becomes the outer shape loop of the analysis area, and the line segment L ₁₃ ... L connected to the line segment. ₁₆ and L _1n are searched in order. Then, when the start point and the end point of the searched polygonal line match (match at P ₁ point) to form a closed loop, the closed loop is set as the outer shape loop of the analysis area. Next, a closed loop group is searched for the line segment groups existing in the outer shape loop in the same manner as the outer shape loop.
When a closed loop exists inside another closed loop in the closed loop group, the operation of deleting the closed loop existing inside from the closed loop group is repeated. The last remaining closed loop group is the hole loop for the outer shape loop. By the above operation, a pattern including the outer shape loop and several hole loops as shown in FIG. 3 is obtained, and is defined as the outermost closed area (two-dimensional surface) E ₁ analysis area. When the analysis area is composed of a plurality of two-dimensional surfaces, the above operation is repeated. In the example of FIG. 3, four two-dimensional planes E ₁ , E ₂ ,
E ₃ and E ₄ are separate analysis areas. Although the analysis areas are selected in the order from the outer loop to the inner loop, there is also a method of selecting the analysis areas in the order from the inner loop to the outer loop. In addition, various analysis conditions necessary for fluid analysis are input by designating a surface, a line, and a point of a two-dimensional figure, and are described as surface attribute data, line attribute data, and point attribute data, respectively. FIG. 7 shows a data structure of a two-dimensional figure representing a two-dimensional topography and an analysis area. A surface data table 701 and a line data table 70 are shown.
2. Point data table 703, pointer table 70
4, a surface attribute data table 705, a line attribute data table 706, and a point attribute data table 707. Each surface on the surface data table 701 is associated with a set of lines on the line data table 702 consisting of outer shape loops and hole loops via the pointer table 704. Further, each line on the line data table 702 is associated with a set of points on the point data table 703 indicating the start point and the end point of the line via the pointer table 704. On the other hand, the surface attribute data, line attribute data, and point attribute data on each table 705 to 707 are associated with the surface data, line data, and point data on each table 701 to 703 via the pointer table 704. For example, water and oil existing on the surface are described as surface attribute data, and the inflow amount of the fluid inlet is the fluid inlet.
It is described as line attribute data of a line on a three-dimensional figure. Further, the height information of contour lines is also described as line attribute data of all the lines forming the contour line (closed polygonal line).

The two-dimensional mesh generation unit 106 sequentially subdivides the two-dimensional surface E ₁ defined by the analysis region definition unit 105 and divides the entire analysis region into a two-dimensional mesh. The other two-dimensional planes E ₂ , E ₃ and E ₄ are similarly divided into a secondary mesh. FIG. 4 shows an example of the result of dividing the _four two-dimensional surfaces E _{1 to} E ₄ into a secondary mesh. For example, the left end E _{11 of} the two-dimensional surface E ₁ is shown as being divided into 24 meshes. It should be noted that the reason for hatching a part of the two-dimensional surface E ₂ in FIG. 4 is to facilitate the understanding of the division between E ₁ and E ₂ in the drawing, and it does not actually exist. Contour height information is added to the nodes (lattice points, that is, the intersections of the meshes) located on the contour lines as attribute data of the nodes.

In the three-dimensional mesh generation unit 107, the above-mentioned two-dimensional mesh data and the height data of the nodes on the contour lines and the height direction division information (the number of divisions in the height direction or the height direction division information inputted by the operator). Three-dimensional mesh data is created from the division width). Figure 8 shows the algorithm.
Shown in. First, in step 801, the two-dimensional mesh data created by the two-dimensional mesh generation unit 106 and the nodal height data on the contour lines are input from the database 103. Next, in step 802, the operator inputs the number of divisions or the division width in the height direction from the data input device 101.
In step 803, using the above two-dimensional mesh data and the nodal height data on the contour line, a Poisson equation with the nodal height on the contour line as a boundary condition is derived, and the heights of all the nodal points of the two-dimensional mesh are obtained. .. Next, in step 804, the division method is selected according to the division information input by the operator. If the number of divisions is specified, step 80
Move to processing of 5. Here, the height of each node is divided by the number of divisions to obtain a division width, three-dimensional nodes for each division width are generated in the height direction, and in step 806 the three-dimensional nodes are connected to form a three-dimensional element. To generate. The figure Q _{1 in} FIG. 9 is an example of a cross-sectional view of a three-dimensional mesh when the number of divisions is constant. on the other hand,
When the division width is specified, the height average of the nodes forming the two-dimensional element is obtained in step 807, and the three-dimensional element having the specified division width is generated in the height direction until the height average is exceeded. However, if the difference between the height of the last created three-dimensional element and the height average exceeds 1/2 of the division width, the last created three-dimensional element is deleted. Then, in step 808, among the nodes on the ground surface, the nodes on the same straight line in the height direction move 1/3 of the element width in the downward direction at the uppermost node and in the upward direction at the lowermost node. By doing so, nodes on the ground surface are smoothed. The figure Q _{2 in} FIG. 10 is an example of a cross-sectional view of a three-dimensional mesh before smoothing when the division width is constant, and the figure Q ₄ in FIG. 11 is an example in which a partial figure Q ₃ in FIG. 10 is extracted and smoothed. Is shown. 5 and 6 are examples of the three-dimensional mesh with respect to FIG. 2. FIG. 5 is a side view of the three-dimensional mesh, showing that a three-dimensional contour mesh is formed between the water surface and the ground. Show.
FIG. 6 is a perspective view of the three-dimensional mesh.

As an application example when the number of divisions is specified, the number of divisions and the height of the mesh layer are input, the region from the ground surface to the height of the mesh layer is divided by the specified number of divisions, and a three-dimensional mesh is obtained. May be generated. That is, the two-dimensional mesh generated by the two-dimensional mesh generation unit 106 is projected on the ground surface, and the coordinate values in the height direction of the nodes of the two-dimensional mesh are obtained.
Generate a ground surface mesh. Next, the height of the mesh layer is divided by the number of divisions to obtain a division width, and the division width is sequentially added to the coordinate values in the height direction of the ground surface mesh to generate three-dimensional nodes. Finally, the three-dimensional nodes are connected to generate a three-dimensional mesh. In this case, a rectangular parallelepiped region including the entire three-dimensional mesh is defined, and the three-dimensional mesh obtained by dividing the rectangular parallelepiped region into orthogonal grids is also passed to the analysis unit. The figure Q _{5 in} FIG. 12 shows an example of the cross section of the three-dimensional mesh and the three-dimensional mesh of the orthogonal lattice in this application example, that is, when the number of divisions and the height of the mesh layer are input. The mesh data and analysis condition data generated as above are
It is used in the analysis program to calculate the flow, temperature, movement of substances, etc. in the space above the surface of the earth.

[0014]

According to the present invention, if map information is input interactively with a computer and a two-dimensional meshing operation is performed, the number of divisions in the height direction or the division width can be simply designated.
The dimensional mesh can be automatically generated. As a result, there is an effect that the conventional interactive operation of the operator for creating the three-dimensional mesh can be omitted and the time for creating the three-dimensional mesh can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an apparatus of the present invention.

FIG. 2 is a diagram showing an example of a two-dimensional figure representing two-dimensional topography.

FIG. 3 is an example view of a two-dimensional surface representing a two-dimensional analysis area.

FIG. 4 is a diagram showing an example of a two-dimensional mesh.

FIG. 5 is an example diagram of a three-dimensional mesh.

FIG. 6 is an example diagram of a three-dimensional mesh.

FIG. 7 is an explanatory diagram of a data structure expressing an analysis area and a two-dimensional topography.

FIG. 8 is a diagram showing a three-dimensional mesh generation algorithm.

FIG. 9 is an example of a cross-sectional view of a three-dimensional mesh with a constant number of divisions.

FIG. 10 is an example of a cross-sectional view of a three-dimensional mesh before smoothing with a constant division width.

FIG. 11 is an example of a cross-sectional view after smoothing.

FIG. 12 is a diagram showing an example in which a three-dimensional mesh and an orthogonal lattice are both generated.

[Explanation of symbols]

 101 data input / output device 102 preprocessor 103 database 104 terrain information input unit 105 analysis region definition unit 106 two-dimensional mesh generation unit 107 three-dimensional mesh generation unit

Claims (10)

[Claims] 1. A topographical information input means for inputting a ground surface height distribution on a two-dimensional topographical map defined by contour lines, and an analysis target based on instruction information from the two-dimensional topographical map input by the means. Analysis area defining means for extracting an area to be defined, a two-dimensional mesh generation means for dividing the analysis area defined by the means into a two-dimensional mesh which is a two-dimensional small area, and the above-mentioned means defined by the means. Numerical value characterized by being provided with a three-dimensional mesh generation means for dividing each columnar space in the height direction of the two-dimensional mesh into a three-dimensional mesh which is a three-dimensional small area having a size corresponding to the instruction information. Space mesh generator for analysis. 2. The topographical information input means uses the contour lines on the two-dimensional topographical map as approximate contour lines having the indicated position as a node and connecting adjacent nodes with a straight line.
The spatial mesh generating apparatus for numerical analysis according to claim 1, wherein a three-dimensional topographic map is loaded. 3. The analysis area defining means has instruction information of 1
When a part of one contour line is designated, the closed contour lines inside the designated contour line are sequentially examined, and the area enclosed by the last closed contour line and the first designated contour line is set as the analysis area. The spatial mesh generation device for numerical analysis according to claim 1 or 2. 4. The analysis area defining means has a plurality of analysis areas sandwiched by adjacent contour lines in the analysis area in a two-dimensional topographic map in which one or more contour lines exist inside the outermost contour line. 3. The spatial mesh generation device for numerical analysis according to claim 1, wherein the spatial mesh generation device is set to be a closed region. 5. The three-dimensional mesh generation means is the two
3. The height of the node generated at the intersection of the boundary lines of the two-dimensional mesh generated by the dimensional mesh generating means is calculated from the height information of the node input by the topographical information input means. The described spatial mesh generation device for numerical analysis. 6. The three-dimensional mesh generation means divides the columnar space in the height direction into a small region of the number of divisions when the instruction information inputs the number of divisions in the height direction. The spatial mesh generating device for numerical analysis according to any one of claims 1 or 2 or 3 or 4 or 5. 7. The three-dimensional mesh generation means divides the columnar space in the height direction into a small region of the division width when the operator inputs the division width in the height direction. Claim 1 or 2 or 3 or 4
Alternatively, the spatial mesh generation device for numerical analysis according to one of 5. 8. A rectangular parallelepiped including the entire three-dimensional mesh generated by the three-dimensional mesh generating means,
One of claims 1 or 2 or 3 or 4 or 5 or 6 or 7 is characterized in that another three-dimensional mesh is additionally generated by dividing the rectangular parallelepiped into orthogonal grids.
The spatial mesh generation device for numerical analysis described in No. 3. 9. The spatial mesh generating apparatus for numerical analysis according to claim 1, further comprising a display unit for displaying the generated three-dimensional mesh. 10. A flow generated in the space above the surface of the earth and a movement of temperature, substances, etc. are analyzed by using the mesh generated by the spatial mesh generator for numerical analysis according to any one of claims 1 to 8. Numerical analysis device.