Simulation of vortex dynamics in a cylinder wake by the Immersed Boundary technique

Abstract

The dynamics of flow past a circular cylinder is investigated at Reynolds number (Re) between 20 and 3900 using the rectangular mesh. The Re is defined based on the cylinder diameter D and the free-stream velocity U∞. This is achieved by using the Immersed Boundary (IB) method that helps to impose boundary conditions on a given surface not coinciding with the computational grid. Two interpolation techniques, namely bi-linear proposed by the authors and unidirectional quadratic by Muldoon and Acharya (2005), are compared for both the laminar and the turbulent flow regime. The unsteady Navier?Stokes (N?S) equations are solved using a symmetry-preserving finite-difference scheme of second-order spatial and temporal accuracy. Large-Eddy Simulations (LES) with the dynamic subgrid model are used to resolve the turbulent flow at Re = 1000 and 3900. When compared with experiments, it reveals that the IB method is worth pursuing and both the interpolations generate almost identical results for a wide range of Reynolds numbers. The bi-linear interpolation is easy to implement and take less computational time because of its simplicity.