Toward high-fidelity simulations of urban flows: mean-flow statistics

This paper demonstrates the capabilities of high-fidelity wall-modeled large-eddy simulations (LES) in characterizing the flow features of a neutral atmospheric boundary-layer over a full-scale urban geometry. Two idealized geometries are considered: an array of three-dimensional square prisms and the "Michelstadt" geometry model. In both cases, the incident wind angle is 0°, and the Reynolds number is ReH = Ure ƒH/¿ ~ O(6), where Ure ƒ denotes the reference velocity, H the height of the tallest building, and ¿ the kinematic viscosity. The LES employs a high-order, low-dissipation numerical scheme with a spatial resolution of 0.75m within the urban canopy. The numerical results exhibit good agreements with experimental data. The discussion focuses on the region below the roughness sublayer, presenting both first- and second-order mean statistics.