Large Eddy Simulation of a Turbulent Boundary Layer Flow over Urban-Like Roughness

Abstract

In this study, Large Eddy Simulation of a boundary layer flow over large-scale roughness was performed targeting the experiments conducted by Cheng and Castro [2]. In order to duplicate the experimental conditions, the quasi-periodic boundary method for rough-wall boundary flows was applied to the inlet boundary conditions. The characteristics of the turbulent boundary layer flows over urban-like roughness (with a roughness area density of 25% and a boundary layer height ratio δ/h around 7) are different from the common homogenous with δ/h larger than 50. The spatial variation of vertical profiles of mean and fluctuation velocities are studied in detail and compared to the experimental data. We focus on the influence on the spatial variations of turbulence structure deduced by large-scale roughness.