A novel method to promote parallel vortex shedding in the wake of circular cylinders

Slanted vortex shedding dominates the wake of circular cylinders of finite aspect ratio in the Reynolds number range of 72–158. Parallel vortex shedding can be induced in the wake of a circular cylinder by imposing a symmetric pressure boundary condition at the two ends of the cylinder. This condition can be achieved by positioning two upstream circular cylinders of larger diameter normal to it. The resulting Strouhal–Reynolds number curve shows no discontinuity. Also, the turbulent transition in the wake of a circular cylinder could be delayed by using this technique.