NUMERICAL-SIMULATION OF VORTEX-WEDGE INTERACTION

Abstract

Interactions between vortical flows and a solid surface cause one of the primary sources of noise and unsteady loading. The mechanism of the interaction is studied numerically for a single Rankine vortex impinging upon a wedge. An Euler-Lagrangian method is employed to calculate the unsteady, viscous, incompressible flows in two dimensions. A random vortex method is used to describe the vorticity dominant field. A fast vortex method is used to reduce the computational time in the calculation of the convection velocity of each vortex particle. A Schwarz-Christoffel transformation is used to map the numerical domain onto the physical domain. Vortex particle plots, velocity vectors, and streamlines are presented at selected times for both inviscid and viscous interactions. It is observed that the incident Rankine vortex distorts and is split by the wedge as it nears and passes the wedge, and the vortices generated from the leading edge toward the underside of the wedge form into a single vortex. The vorticity orientation of the shed vortex is opposite to that of the incident vortex. It is found that the convection velocity of the shed vortex is changed when it comes off the leading edge of the wedge, and the strength of the shed vortex varies with time during the vortex-wedge interaction. This strength variation is presumed to influence the shed vortex convection velocity. The overall features for the interaction agree well with the experimental results of Ziada and Rockwell.1