Numerical study of fluid flow past a rotating elliptic cylinder

Numerical solutions are presented for fluid flow past a rotating elliptic cylinder for different non-dimensional rotational rates (0.5, 1.0 and 1.5) and various axis ratios (0.1, 0.3, 0.5, 0.7 and 1.0). The two-dimensional, incompressible Navier–Stokes equations are solved using Immersed Boundary method on a non-body conforming Cartesian grid. Reynolds number based on the perimeter of the elliptic cylinder is 100. Periodic flow after an impulsive start of the elliptic cylinder is studied. Flow patterns and variation of aerodynamic force coefficients are reported for different set of parameters and it is observed to be very different from that of rotating circular cylinder. As the cylinder rotates, the trailing edge of the cylinder aids the flow while the leading edge deters the flow. This has significant effect on the wake region and vortex shedding pattern. Complex interactions between cylinder and shed vortices result in many interesting phenomenon, such as formation of hovering vortex. Parameters affecting the formation of hovering vortex and its underlying mechanism are analyzed. Aerodynamic force coefficients and vortex shedding frequencies are presented and it is observed that force coefficients have multiple amplitudes and frequencies.