Development And Study Of Boundary Element Method Automatic Mesh Generation System

The Preprocessing Technology of Boundary Element Method (BEM) is the precondition of BEM kernel program and Postprocessing program. And Mesh Generation is the key point in Preprocessing. The dissertation mainly focuses on how to generate 2D structured and unstructured mesh and how to generate 3D structured and unstructured surface mesh. The dissertation utilizes Computer Graphics, Geometry, Theory of Data Structure and OpenGL programming in the programming environment of Visual Basic to study BEM mesh generation in details, It mainly includes the realization method and steps of structured and unstructured triangulation in 2D complicated connected region, the realization method and steps of structured and unstructured triangulation in 3D surface region, BEM mesh generation of intersecting tunnels, BEM 3D terrain mesh generation which bases on the data extracted from terrain contours, and Visualization in displaying the result of triangulation, and so on.The dissertation studies structured mesh generation in details. And it includes the method of cells and nodes numbering, constructing data structure and how to get the nodes coordinates. The technique unwrapping surface to deploy nodes and triangulating 3D surface is brought forward and it brings effective result.Unstructured mesh generation is the main trend of mesh generation. It can be used widely and the deployment of cells is not be restricted by the amount of neighboring cells. The dissertation also bats around the approach and detailed steps of unstructured mesh generation in 2D complicated connected plane area. Mapping method and amendatory measures are put forward in 3D surface mesh generation.As to the mesh generation in 3D surface joint by two different tunnels which have random cross sections, the normal way to construct the line of intersection is to get the intersecting line equation through solving the two surface equations of intersecting tunnels. However, the dissertation avoids complicated computation by introducing Tracing Method to construct the nodes on the line of intersection, and the method can solve the mesh close problem near the intersecting line effectively.The key of simulating terrain boundary condition is that constructing BEM 3D terrain...