Effect of a slip splitter plate on vortex shedding from a cylinder

The effect of placing a "slip" splitter plate in the wake of a circular cylinder along the line of symmetry is studied. Such a hypothetical plate allows slip of velocity along itself but prevents any flow normal to it. Unlike the conventional splitter plate the slip plate does not have a wake of its own. The objective of the present study is to increase our understanding of vortex shedding by tracking down that part of the wake that needs to be constrained to suppress it completely. Computations for various configurations of the plate for the Re=100 flow are carried out using a finite element formulation. It is found that the shortest length of the plate required to suppress vortex shedding is two cylinder diameters, approximately, and needs to be located in the latter part of the wake bubble of the basic unperturbed flow. In this region the vertical component of velocity in each of the two standing vortices is towards the centerline. The upstream edge of the optimal plate is located very close to the region in the wake bubble where the vertical velocity component changes direction. As compared to the downstream edge, the location of the upstream edge of the plate has a much more significant effect on the unsteadiness of the flow. This study establishes that the latter part of the wake bubble of the basic unperturbed solution plays an important role in vortex shedding.