Geometry Effects on Quasi-Steadiness of the Flow Around a Heaving Rectangular Cylinder at Low Reynolds Number

In last year’s APS-DFD meeting (abstract G03.00003), we showed that in the limit of sufficiently low Reynolds number (below ≈ 10,000<!--[if gte msEquation 12]> style='mso-bidi-font-style:normal'>≈10,000), attainment of quasi-steady conditions for the flow around a heaving sharp-corner rectangular cylinder depends on the reduced velocity-Reynolds number product (U_r Re_d; d is the cylinder thickness).This finding augments the established understanding in literature in which quasi-steadiness depends on U_r alone. In the present study, we conduct experiments to examine the influences of geometrical parameters on the quasi-steady behavior of the cylinder in the same Reynolds number range (1,000 ≤ Re_d ≤ 10,000). As we vary these parameters, which include the cylinder’s corner radius and side ratio, we investigate the presence of non-quasi-steady behavior over a range of reduced velocities, oscillation amplitudes and Reynolds numbers. The experiments are conducted in a water tunnel to characterize the unsteady force on a cylinder undergoing forced harmonic oscillation. Analysis of the force, and associated oscillation energy, are used to examine the quasi-steady behavior of the cylinders.