Unsteady Turbulent Vortex Structure Downstream of a Three Dimensional Cylinder

Abstract

This study examines the near wake behavior of the turbulent, unsteady flow over a three dimensional circular cylinder at Re=20,000, based on cylinder diameter, computationally. From a CFD perspective, this work assesses the capability of unstructured grids and large eddy Simulations without a subgrid scale model, for the prediction of flow behavior at transitional Reynolds numbers for the time-dependent flow over a circular cylinder. Proper orthogonal decomposition is also applied to the computational results in order to investigate the flow structure further and examine the energy content of the turbulent flow at hand. The results of the computations arc in close agreement with the experimental results in literature. The energy content of the POD modes reveals that only four spatial modes have 98% of the total energy in the flow and arc enough to represent the flow.