Numerical study of flow over a circular cylinder in oscillatory flows with zero-mean and non-zero-mean velocities

Abstract

This paper numerically investigates flow over a circular cylinder in oscillatory flows with zero-mean and non-zero-mean velocities. The effects of Keulegan–Carpenter number and amplitude ratio number on vortex shedding around a cylinder are investigated. The applicability of Morrison's equation to prediction of the time histories of drag and lift forces is discussed. Results of the present study show that the unsteady flow pattern around a circular cylinder depends strongly on both Keulegan–Carpenter number and amplitude ratio number, in addition to Reynolds number. Although the time history of drag force can be acceptably approximated by Morrison's equation in both zero-mean and non-zero-mean velocity flows, multiple vortex shedding frequencies need to be included if Morrison's equation is extended to approximate the time history of lift force.