Vortex shedding in shear flow past tandem square cylinders in the vicinity of a plane wall

The flow of incompressible fluid past a pair of square cylinders in tandem placed close to a flat wall is studied in the presence of an incident linear velocity profile. The flow field is considered for a separation distance between the wall and the cylinders wall-side face at 0.5 times the height of the cylinder, at various values of spacing distance between the cylinders. The flow field is assumed to be laminar and two-dimensional for Reynolds number (based on the height of the cylinder D and the incident stream U at the centreline of the cylinders) up to 200. The governing unsteady Navier–Stokes equations are computed through a finite volume method over a staggered grid arrangement. A QUICK scheme is employed for the convective terms. The code has been tested for accuracy by comparing with the published results for certain values of the flow parameters. With the aid of vorticity contours, Strouhal number and velocity profiles, the interactions of the asymmetric separated shear layers emerging from either side of each cylinder and the wall boundary layer are studied for low to moderate values of inter-cylinder spacing distance. The effects on the force experienced by the cylinders is also considered in the present study. The flow field is found to be steady up to a certain critical Re. This critical value of Re depends on the spacing ratio of the cylinders. The plane wall encounters unsteady separation when cylinders exhibit vortex shedding. The flow characteristics for the present configuration is compared with the corresponding unbounded case and the case where a single cylinder exposed to shear flow in close proximity of a plane wall.