Computational Study of Vortex Shedding Control for Flow Past Circular Cylinder

Abstract

A Numerical investigation on flow past cylinder has been carried out in laminar flow regime. The possibilities of vortex shedding suppression and its control for the case of both confined and unconfined cylinder has been studied. For the case of cylinder confined by walls parallel to the cylinder axis, a new technique local waviness in the confining wall has been implemented for vortex shedding suppression and drag reduction. Two different waviness configurations, viz., in-phase configurations (IPC) and out-phase configurations (OPC) are considered and the effect of location of the local waviness with respect to the cylinder has been studied. The finite volume based CFD solver Ansys Fluent (Version 15.0) is used for computations. Flow characteristics such as drag, lift and Strouhal number are computed. Interesting shedding characteristics and drag reduction are observed due to the presence of local waviness. Among various locations and configurations of waviness studied, OPC in the downstream suppresses the vortex shedding completely with reduced drag. Therefore for this location and configuration, the study is further continued to identify the effect of amplitude of local waviness. It is found that local waviness with amplitude A=0.15D is an optimum value for effective vortex shedding suppression with reduced drag on the cylinder at Re=200. As the amplitude of waviness increases, the wake size is reduced significantly as compared with plain wall confined cylinder. The presence of crest closer to the cylinder in the downstream generates a favorable pressure gradient and prevents flow separation at Reynolds number 20. newline