LES analysis of the aerodynamic surface properties for turbulent flows over building arrays with various geometries

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

This paper describes the applicability of roughness-length and drag-force approaches of mesoscale meteorological models to actual urban areas. We first investigated building morphological characteristics. Then, we performed large-eddy simulations (LESs) of turbulent flows over building arrays with various surface geometries that are characterized by a wide range of values for not only roughness density and but also building height variability. Then, we evaluated the aerodynamic roughness parameters such as roughness length and drag coefficient for central Tokyo area using the LES results. The values of roughness length and drag coefficient as a function of both roughness length and building height variability is comparable to those in the previous studies. The roughness aerodynamic parameters as a function of roughness length and drag coefficient obtained from our LES results are useful to incorporate the urban effects into weather forecasting models.