Modification of flow around a circular cylinder using porous media

Flow around a circular cylinder having a porous surface is studied numerically by means of direct numerical simulation (DNS) and large eddy simulation (LES). The flow in the porous media is represented by a spatially-averaged (i.e., macroscopic) model. The parameters of the most effective porous media are found from a two-dimensional parametric test at the Reynolds number, based on the free stream velocity and the diameter of cylinder, of Re = 1000. The lift force fluctuation is notably reduced in the case of thicker porous surface. The DNS of three-dimensional flow at Re = 1000 reveals that the porous surface works to stabilize the shear layer. The LES at a very high Reynolds number (Re = 10⁵) shows that the vortex shedding is completely suppressed by the porous media, which supports the experimental observation by Sueki et al. (2007). Simulations at different Reynolds numbers show that the stabilization effect works better at higher Reynolds numbers.