| Much more recent research works focus on unstructured grids for its simplicity in dealing with complex boundary conditions and more easily being constructed compared with structured grids. In this thesis, Advancing Front Method (AFM) is studied and used to generate 2D and 3D unstructured grids.Advancing front approaches start from a discretization of the domain boundaries as a set of edges in two dimensions or a set of triangular faces in three dimensions, (i.e., the domains are considered as bounded regions). The name of this class of methods refers to a strategy that consists of creating the mesh sequentially, element by element, creating new points and connecting them with previously created elements, thus marching into as yet unmeshed space and sweeping a front across the domain. The process stops when the front is empty, i.e., when the domain is entirely meshed.In this thesis, the automatic generation of 3D unstructured grids for complex geometric configuration object using AFM is described. The required geometric data is available in the form of CAD parametric curves and surfaces. The data format is compatible with that of a CAD system. If a definition of surface as a mapping from a 2D region, this can be used to generate a grid in the 2D region, which, at a later stage, will be transformed onto the surface. The background-mesh is used to refine location grids. A mesh refinement technique is also discussed to obtain more accurate solution. In addition, ADT structure is applied to the generation of grid for improving the efficiency. Unstructured meshing with moving boundaries is also investigated using AFM.Finally, the developed mesh generation code is employed to simulate the propagation phenomena of a blast wave in a T channel with a round roof. Numerical results show that the mesh generation based on Advancing Front Method is robust, efficient and flexible. Besides, surface meshes can be constructed by taking advantage of the surface transformation. |
PDF Full Text Request