CFD analysis of 2D unsteady flow around a square cylinder

Unsteady flow around bluff bodies is an area of great research for scientist for several years. Flows around buildings, chimneys are examples where the fluid is in motion. Atmospheric dispersion of pollutants around bluff bodies has intensified the need to understand wake behavior. The vortex shedding frequency depends on different aspects of the flow field such as the end conditions, blockage ratio of the flow passage. In the present work a numerical simulation was carried out for flow past a square cylinder to see the wake behaviour. A twodimensional unsteady flow past a square cylinder has been investigated numerically for the Reynold number (Re) considered in the range 50250 so that flow is laminar. The main objectives of this study were to capture the features of flows past a square cylinder in a domain with the use of CFD. Finite volume method has been used with staggered grid arrangement. The incompressible SIMPLE algorithm was used for the velocity pressure coupling. The second order discretisation was used both for space and time. Power law scheme was used on a nonuniform grid and for time discretisation CrankNicholson was used. A high resolution grid has been used to avoid spurious oscillations and to keep the errors within limits. The lift coefficient and velocity component in the wake region were monitored for calculation of Strouhal number. The variation of Strouhal number with Reynold number was found from the analysis.