Hydrodynamics of the Flow Around a Circular Cylinder Sheathed by a Porous Layer

A detailed study of the turbulent flow at Re = 3900 around a circular cylinder, sheathed at some small distance by a porous layer, has been performed by means of Direct Numerical Simulation with a commercial unstructured finite volume based Computational Fluid Dynamics solver. First, to benchmark the performance of this code and the validity of the applied local grid refinement, simulations of the flow around a bare circular cylinder at the same Re were performed. Results were compared to that of an academic CFD solver and to numerical and experimental data from literature and good agreement was found. Subsequently, a detailed study of the flow around a porous layer sheathed cylinder at the same Re, was performed. The flow in the space between the outer porous and the inner solid cylinder was found to be laminar and periodic, with a frequency locked to that of the vortex shedding in the wake behind the cylinder. A good agreement was found to experimental data from literature.