Large-eddy simulation of turbulent flow over an array of wall-mounted cubes submerged in an emulated atmospheric boundary-layer

Abstract

Turbulent flow over an array of wall-mounted cubic obstacles has been numerically investigated using large-eddy simulation. The simulations have been performed using high- performance computations with local cluster systems. The array of cubes is fully submerged in a simulated deep rough-wall atmospheric boundary-layer with high turbulence intensity characteristics of environmental turbulent flows. Four different approaches have been tested to reproduce the approaching highly turbulent inflow condition. Significant influence of the inlet boundary condition on the predictive streamwise root mean squared velocity (and second-order turbulence statistics if generalized) have been observed. A pro- posed method based on inserting a solid grid at the inlet of the domain with superimposed correlated random fluctuations has been selected as the inlet boundary condition to conduct the simulations. Three different subgrid-scale (SGS) models have been also used to compare their predictive performance in turbulence statistics and temporal energy spectra. It was observed that the choice SGS model does not have considerable effect on the second-order turbulence statistics, however, it was influential on the predicted energy level in the energy spectra. It was also observed that the flow reaches a self-similar states after the second row of obstacles which was different from the reported value in some of the previous studies.