Abstract
This study investigates changes of flow pattern of wake behind an obstacle by the horse-shoe vortex system. The experiments were carried out by flow visualization and PIV for flows around the obstacle (40mm height (h) and 20mm width (d)) mounted on a flat plate in a water channel. Features of flow patterns appeared were examined by flow visualization and the results of PIV which are u, u_<rms>, and -<u'v'>^^^-. As a result, it was found that there are only two kinds of flow patterns as well as the case of h/d=0.5 in previous work. Also, the Reynold's number distinguishing both flow patterns is about 400,which is very small in comparison with <Re>_d=1300 obtained in the previous work.
