LES analysis of the aerodynamic surface properties for turbulent flows over building arrays with various geometries and its application to actual urban area

Nakayama, Hiromasa   ; Takemi, Tetsuya*; Nagai, Haruyasu  

There are important issues of treatment of urban ground surfaces for both the roughness and drag force approaches in mesoscale meteorological models. Thus, for using the roughness approach, the geometry type of urban surface where the roughness length is appropriately estimated should be considered. On the other hand, for using the drag force approach, the drag coefficient values also should be evaluated by considering the complex geometry of urban surface. Therefore, in this study, we first examine the building morphological characteristics in some actual urban areas and set up building arrays that represent realistic urban surface geometries. Then, we perform LES of turbulent flows over various urban-type surfaces of building arrays and investigate the relationship between the aerodynamic roughness parameters and the building morphological characteristics.