Flow Control Around a Cylinder With a Perforated Cylinder

Abstract

In this work, periodic vortex shedding at both sides of a circular cylinder is aimed to be suppressed using a concentrically located perforated cylinder under laminar flow conditions at Re = 200. A code is developed in comsolmultiphysics, 5.3a, and validated using the outcomes of ansysfluent, and previous studies in the open literature, which exhibit a good agreement. In this study, the porosity, β is varied within 0.5 ≤ β ≤ 0.9, and the gap ratio, D/d is varied within 1.5 ≤ D/d ≤ 3.5. The results of the present numerical investigation are evaluated using instantaneous and time-averaged vorticity, streamwise, and transverse components of the velocity and pressure. The drag, CD and lift, CL coefficients are calculated. The Strouhal number, St from the pointwise spectral analysis of the streamwise velocity component is plotted for various cases. It is observed that porosity, β has a dominant effect rather than the gap ratio, D/d on the flow past a solid cylinder. The low-velocity and low-pressure regions are getting large in the transverse direction as the porosity, β increases. The separated layers from solid and perforated cylinders merge for low gap ratios, D/d. However, individual movement of these layers is evident for larger gap ratios, D/d with low porosity, β values. A perfect suppression of the periodicity of vortex shedding is obtained for the cases of D/d = 3.5 with β = 0.5, 0.6, and D/d = 3 with β = 0.5.