Simulation of Flow over a Rotationally Oscillating Square Cylinder at Low Reynolds Numbers

Abstract

Simulation of uniform flow past a square cylinder undergoing rotational oscillations at various frequencies is performed using the ANSYS Fluent CFD package. The frequency ratios FR chosen for the study are 0.4, 0.8 and 1.0. At each frequency ratio, a number of angular amplitudes are selected, and the simulations are performed using a dynamically deforming mesh. The results are obtained from the simulations in terms of the non-dimensional drag and lift forces, vorticity contours, power spectral density plots of lift coefficients and Strouhal number. A general increase in lift and drag coefficients with increasing frequency ratios as well as with increasing amplitudes at a particular frequency ratio, except a few anomalies, is seen. The flow features in the wake and the vicinity of the cylinder are compared for the various parameters. The use of convective boundary condition for the problem is demonstrated.