On the onset of vortex shedding past a two-dimensional porous square cylinder

Vortex shedding is an interesting phenomenon and a fundamental problem when it comes to flow across bluff bodies. Generation of vortices behind a porous bluff body is further compelling to study. In this paper, a numerical investigation on the onset of vortex shedding behind a porous square cylinder is presented for 41 <= Re <= 50 and the computations are performed for different values of permeability (Darcy number, Da = 10(-6) - 10(-2)) and porosity (epsilon = 0.629 - 0.993). Besides, an outlook on unsteady flow across the permeable cylinder is provided for Re = 50 - 150. The numerical simulations are performed by modifying pimpleFoam solver of OpenFOAM 4.1 coupled with Darcy-Brinkman-Forchheimer model, using a single domain approach. Current study provides an insight on the influence of permeability on the initiation of vortex shedding behind the porous bluff body. A brief discussion is provided on the jump in flow characteristics, at intermediate values of Darcy number, comparing square with other bluff shapes. Also, a correlation for the frequency of vortex shedding is given in terms of the flow and material parameters. Optimistically, scholars and engineers working on flow control using porous media will benefit from the information presented in this article.