Numerical Experiment of Flow around a Self-Oscillating Circular Cylinder by a Vortex Method Combined with Boundary Layer Calculation. (The Flow Features and the Motion of Circular Cylinder in the Initial Stage of Self-Oscillation)

Abstract

In this study, the flow features of vortex shedding from a self-oscillating circular cylinder and the characteristics of fluid force were examined using a vortex method simulation combined with boundary layer calculation in a uniform flow at high Reynolds number in order to investigate validity and applicability to the analysis of the flow-induced vibration problems. The calculations were performed for the parameters of the mass ratio M (=1.78, 5.15), the damping factor C (=0.0, 0.0153) and the reduced velocity Vr (=1.38-4.13) at the Reynolds number Re=1×105 based on the uniform flow velocity U and the cylinder diameter D. As a result of the calculations, two typical patterns of vortex shedding were observed, one of which is symmetric twin vortex shedding and the other is antisymmetric twin vortex shedding. It was confirmed that the calculated flow patterns and the free-oscillation motions of the cylinder, were in reasonable agreement with experimental results. The relationship between the fluid force and the resultant cylinder's displacement was investigated.