Large-eddy simulation of turbulent flow and dispersion over a matrix of wall-mounted cubes

Turbulent flow over a matrix of wall-mounted cubic obstacles along with continuous release of a passive scalar from a ground-level point source has been investigated using wall-modeled large-eddy simulation (LES). The cubes are fully submerged in a modeled urban atmospheric boundary layer with high turbulence intensities. An inlet boundary condition has been proposed to reproduce the high turbulence level of the approaching flow based on generation of grid turbulence. Coherent flow structures induced by the cubes and their influences on dispersion of the concentration plume in the context of the highly disturbed flow are also investigated. The spatial evolution and temporal cascades of the kinetic and scalar energies have been examined in terms of their transport equations and resolved spectra. In order to validate the LES approach, numerical predictions of turbulence statistics for both velocity and concentration fields have been thoroughly validated against a set of comprehensive water-channel measurement data.