Numerical Study of Reynolds Number Effects on Flow over a Wall-Mounted Cube in a Channel Using LES

Abstract

Turbulent flow over wall-mounted cube in a channel was investigated numerically using Large Eddy Simulation. The Selective Structure Function model was used to determine eddy viscosity that appeared in the subgrid scale stress terms in momentum equations. Studies were carried out for the flows with Reynolds number ranging from 1000 to 40000. To evaluate the computational results, data was compared with experimental results at Re=40000, showing a good correspondence. In this study the effect of Reynolds numbers on flow characteristics such as time-averaged streamlines, turbulent intensity and Reynolds stresses were investigated. Results of computations show that the flow with higher Reynolds number has a shorter reattachment length and by increasing the Reynolds number, the number of horseshoe vortex in the upstream decreases. The vortex structures were similar in the upstream of the cube for time-averaged and instantaneous flow field. While on the downstream, the vortex structure does not show any similarity and had complex flow field structure. Reynolds stress was became stronger at the sides of the cube where the horseshoe vortexes were built and its become more significant at the higher Reynolds number.