Effect of inlet shear on turbulent flow past a wall-mounted finite-size square cylinder

Abstract

The present study analyzes the effect of incoming shear flow on the wake behind a wall-mounted finite-length square cylinder of aspect ratio (AR=7) using large eddy simulation (LES). All the simulations were performed at a Reynolds number (Re) of 10000, based on cylinder width (d) and average inlet velocity (uavg), with different shear parameters, K=0.0,0.025,0.050 and 0.075. The shear-improved Smagorinsky model Lévêque et al. (2007) is used to account for the subgrid scale stress. It is found that the incoming flow shear has a profound effect on the modes of shedding. With increasing shear parameter anti-symmetric modes of shedding tends to dominate along the cylinder height, except close to the free-end where both symmetric and anti-symmetric modes of shedding co-exist. The incoming shear flow has also significant influence on the downwash flow from the free-end, the strength of which decreases with an increase in shear parameter. The resolved turbulent kinetic energy (TKE) associated with the cylinder wake is found to have maximum contribution from the transverse component of normal stress compared to the other components of normal stresses.