Numerical modeling of turbulent flows over an urban-type surface: Computations for neutral stratification

Computations of turbulent flows over surfaces with explicitly specified roughness elements that imitate an urban built-up area have been performed using a large-eddy simulation (LES) model. Results are presented for neutral stratification. Some statistics of the flow over an inhomogeneous surface are compared with those over a flat surface. Results of spectral analysis performed to identify characteristic length scales are discussed. A relation is established between the Prandtl mixing length and the turbulence scale defined through the cospectrum-weighted-mean wave number. Values of the roughness parameter and displacement height are determined for three different configurations of objects on the surface.