Efficient strategies for adaptive 3-D mesh generation over complex orography

Abstract

In the FEM simulation of processes that occur in a three-dimensional domain defined over an irregular terrain, it is fundamental to have a mesh generator being capable of adapting itself to the topographic characteristics. The objective of this work is to develop a code able to generate a tetrahedral mesh from an optimal node distribution in the domain. This last one is limited in its lower part by the terrain, and in its upper part by a horizontal plane placed in such a height that the magnitudes under study may be considered steady. The lateral walls are formed by four vertical planes. The main ideas for the construction of the initial mesh combine, on one hand, the use of a refinement/derefinement algorithm for two-dimensional domains; and, on the other hand, a tetrahedral mesh generator algorithm based on Delaunay triangulation. Moreover, it is proposed a procedure to optimise the resulting mesh. It is also analysed a function to define the vertical distance between nodes distributed in the domain, and several strategies for the appropriate generation of the corresponding set of points are proposed. Finally, in order to show the efficiency of these techniques, every strategy is applied to the construction of meshes adapted to the topography of a south part of La Palma (Canary Islands).