EVALUATION OF GMSH MESHING ALGORITHMS IN PREPARATION OF HIGH-RESOLUTION WIND SPEED SIMULATIONS IN URBAN AREAS

Abstract. This paper aims to evaluate the applicability of automatically generated meshes produced within the gmsh meshing framework in preparation for high resolution wind speed and atmospheric pressure simulations for detailed urban environments. The process of creating a skeleton geometry for the meshing process based on level of detail (LOD) 2 CityGML data is described. Gmsh itself offers several approaches for the 2D and 3D meshing process respectively. The different algorithms are shortly introduced and preliminary rated in regard to the mesh quality that is to be expected, as they differ inversely in terms of robustness and resulting mesh element quality. A test area was chosen to simulate the turbulent flow of wind around an urban environment to evaluate the different mesh incarnations by means of a relative comparison of the residuals resulting from the finite-element computational fluid dynamics (CFD) calculations. The applied mesh cases are assessed regarding their convergence evolution as well as final residual values, showing that gmsh 2D and 3D algorithm combinations utilizing the Frontal meshing approach are the preferable choice for the kind of underlying geometry as used in the on hand experiments.