Study on translating and oscillating body near a Free surface*

In this numerical study of fluid flow past elliptic cylinder, the effect of the presence of a free surface is analyzed. The fluid-fluid interface is tracked by the Level set method proposed by Osher and Sethian and the rigid elliptical cylinder is approximated by immersed boundary projection method, both of these methods are incorporated in an in-house code.

The effect of the interface is observed for the forces experienced by the ellipse and the wake of the ellipse. The shape of the interface is also compared for different configurations and kinematics. The parameters investigated are Froude number and kinematics for a fixed Reynolds number. The considered motions are oscillation parallel to the interface with pure pitching motion near the interface.

The interface vicinity changes the wake dynamics significantly for stationary bodies. While in some cases where flow becomes stabilized. Similarly, the forces on the body also vary as the interface proximity is changed. This study also compares the interfacial topology for various cases. Motion of the body causes instability in the shear layers present in the flow that leads to different vortex shedding mechanisms.