Numerical study of flow around an oscillating diamond prism and circular cylinder at low Keulegan-Carpenter number

In order to identify the influence of shape corners on the instantaneous forces in the case of oscillating bodies, the simulated flow field is compared for two kinds of cross sections: diamond prism and circular cylinder. For these two flow configurations, the same Reynolds number and a Keulegan-Carpenter are considered. To compute the dynamic flow field surrounding the body, the Navier-Stokes transport equations in a non-inertial reference frame attached to the body are considered. Hence, a source term is added locally to the momentum equation to take into account the body acceleration. The proposed model is solved using the PHOENICS code. For the oscillating circular cylinder, the simulated results are in good agreement with the experimental data available in the litterature. After validation of this proposed model, flow field for diamond prism is determined. For both bodies, the process of the vortex formation is similar, with the formation of a recirculation zone in the near-wake containing a symmetric pair of vortices of equal strength and opposite rotation. The length of recirculation zone varies approximately linearly with time. However, the in-line force coefficient of the oscillating diamond prism is found to be greatest, since the recirculation zone is longer compared with that of the oscillating circular cylinder.