A prototype mesh generation tool development for CFD simulations in architecture domain

Computational Fluid Dynamics (CFD) has been introduced to the architectural engineering and HVAC (Heating Ventilation and Air Conditioning) industry for decades. Its effectiveness in assisting the architects and engineers in the design process has been well acknowledged. However, the mesh generation process is complicated and time consuming, especially for modeling free form geometric artifacts, e.g., buildings in complex terrains or human bodies in the room. This paper presents the effort to apply quality mesh generation to CFD simulations in architectural applications. A prototype meshing tool is developed to construct adaptive quadrilateral meshes from two-dimensional image data, e.g., architecture drawings. First the quad-tree based isocontouring method is utilized to generate initial uniform quadrilateral meshes in the immediate region surrounding the boundary of the objects. Boundary vertices are recalculated to improve the geometry accuracy. Meshes are decomposed into finer quads adaptively near the surface of the object without introducing any hanging nodes. Boundary layers are generated using the pillowing technique and the thickness of the boundary layer is controlled to achieve the desired y+ values, according to various requirements of near wall turbulence models. After generating fine meshes in the immediate region, the meshes are extended to the ambient domain with desired sizes, where flow fields are relatively steady. The developed tool has been employed to generate meshes for two demonstrations: the wind flow field at the ambient of the Reichstag Building (high-Reynolds-number flow), and the natural convection around an occupant in the indoor environment (low-Reynolds-number flow).