HYDRODYNAMIC FORCE EXERTING ON A SQURE PILLAR IN UNSTEADY FREE SURFACE FLOWS

Abstract

Flow characteristics of 1-D dam break flows and hydrodynamic force exerted on a square pillar placed by the flow were measured by a 2-component load cell. The angle of attack of the pillar and the ratio of channel width to the pillar width (blockage-ratio) were kept 0 degree and 10, respectively. It is found that the velocity profile of the flow with no presence of a pillar follows approximately logarithmic velocity distribution on the smooth wall, and that the ratio of surface to depth-averaged velocity is about 1.12. The magnitude of drag coefficient of the pillar 1-D dam break flows is compared with that of steady uniform flows. The former increases very slowly with t_* after t_*>70.