Study on Transition Process of Unsteady Horse-shoe Vortex by PIV

The present study quantitatively analyzes changes of flow patterns occurring in unsteady horse-shoe vortex systems, using a flow visualization and spectral analysis for fluctuations of velocity, u', measured by PIV. Experiments were performed for flows around an obstacle (prism or cylinder) mounted on a flat plate in a water channel. As a result, it was proved that the changes of flow patterns in the transient process enable to clarify quantitatively, using the results of the auto-correlation, the power spectrum and the cross-correlation.