Evidence and physical mechanism for vortex-induced vibration of a bluff body without an afterbody

Afterbody—the portion of the body downstream shear layer separation points—was believed to be essential for vortex-induced vibration (VIV) a bluff body. A recent study by Zhao et al. [“Flow-induced D-section cylinders: An afterbody is not vibration,” J. Fluid Mech. 851, 317–343 (2018)] made an important forward demonstrate “an required VIV” through water tunnel experiments reversed prism. However, our direct numerical visualization showed that appears at curved front surface prism, leaving part afterbody, which makes their evidence questionable. The present aims provide solid and experimental statement using elastically mounted triangular prism with one vertex pointing upstream. By conducting two- three-dimensional simulations experiments, we verified even without can freely vibrate. Furthermore, physical mechanisms excitation sustenance VIV are investigated. decomposing lift force into pressure viscous parts, discover excited sustained component acting on forebody, in contrast circular cylinder always results energy dissipation damps vibration. Some does occur reasons also explained: absence due either high-Re or large mass ratio (structural damping) but owing lack afterbody.