Effect of frontbody and afterbody on flow-induced vibration of a cylinder*

The effect of frontbody and afterbody on Flow-Induced Vibration (FIV) of an elastically mounted rigid cylinder has been a subject of major interest for the past decade. We present a numerical study on the FIV of the cylinder at Re=100, and the fluid-structure interaction solver is based on a sharp interface immersed boundary method (Sharma et al. J. Fluids Strut, 2022). The cylinders with the following cross-section are considered: circular, inverted D, C, D and inverted C. D and inverted C cylinders exhibit a combined VIV-galloping response, and we discuss the effect of reducing frontbody on these two cylinders. We explain the initiation of lock-in for these cylinders prior to Strouhal frequency approaching the structural natural frequency by a "modified Strouhal number" and discuss its origin using a quasi-steady galloping analysis.