Confinement effects on flows past an in-duct rectangular bluff body with semi-circular leading edge

Abstract

This paper reports a numerical study of a two‐dimensional time‐dependent viscous flow past a rectangular bluff body with a Reynolds number Re = 6 073 based on bluff body height installed in a flow duct. The leading edge of the bluff body takes a semi‐circular profile. The governing equations of the flow are solved with large‐eddy simulation (LES) using a commercial computational fluid dynamics software FLUENT. The focus of the present study is to explore the effects of the ratio of the height of the bluff body H and the separation D between the bluff body and the duct wall surface. The numerical simulations are validated with the results obtained from a separate wind‐tunnel experiment. Numerical simulations with various D∕H are carried out. The numerical results show that the mean and instantaneous flow quantities are strongly dependent on the ratio D∕H. The suppression effects of vortex shedding by the neighboring duct wall are highlighted by comparing the unsteady flow structure topology, dominant Strouhal number, lift and drag forces, etc. The mechanism for the suppression of vortex shedding suppression and its variation with D∕H are analyzed, and its relevance to generation of flow inducing noise by a bluff body in a flow duct is discussed.