Flow Control Around a Cylinder With a Perforated Cylinder

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, C_D and lift, C_L 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.