Numerical analysis of flow around porous rectangular cylinders with uniform injection or suction

The flow around rectangular cylinders of various aspect ratios of B/H = 2, 3 and 4 with uniform injection or suction through the rear and top/bottom surfaces has been studied numerically at a Reynolds number Re = 21,400. The effects of injection or suction through the cylinder surfaces have been linked to the analysis via the wall functions of the viscous sub-layer and log-law layer. The injection or suction has been characterised by an injection coefficient CQ = v(w)/u(infinity), which takes negative values for suction. The governing equations, which are a combination of the ensemble-averaged Navier-Stokes equations for incompressible flow in conjunction with the equations of a modified k-epsilon turbulence model, have been solved by the finite volume method. A non-uniform staggered grid arrangement has been used to economise on computing time. The results show that the vortex structure in the wake is influenced primarily by suction through the top and bottom surfaces of the rectangular cylinders. In addition, the parameters taken into account such as drag coefficient and Strouhal number are also affected by the injection coefficient as well as the injection/suction surfaces of the rectangular cylinders.