COMPUTATION OF VORTEX LOCK-IN IN THE LAMINAR WAKE OF A CIRCULAR-CYLINDER USING UNSTEADY MONOPOLE SOURCES

The vortex lock-in in the laminar wake behind a circular cylinder indu ced by the unsteady monopole source is numerically simulated in this p aper. The artificial compressibility method is employed to solve the i ncompressible Navier-Stokes equations. A high-order accurate upwind fl ux-difference finite-volume scheme is used to discretize the flow fiel d. The unsteady monopole source is simulated by a pulsating volume flu x through the cylinder surface at a prescribed forcing frequency and a mplitude. The forcing amplitude is set to a fixed value while the freq uency is varied to search for the lock-in region. The flow field of th e periodic lock-in state is examined in detail. Finally, the effects o f a higher amplitude and a different source location are briefly inves tigated.