STUDY ON LOCAL SCOUR AROUND CIRCULAR CYLINDER WITH RIBLET

Abstract

It is very important for bride safety to prevent a local scour around a bridge pier. The down flows from horseshoe vortex have an important role on the scour around the pier. Local scours should be controlled if we can handle horseshoe vortexes. Saito et. al. have investigated the local scour around the pier with a horizontal rectangular groove that is called a horizontal riblet. They have reported that the horizontal riblet can reduce the maximum scour depth by 20-50% comparing with the depth obtained by pier with no riblet. However, the effect of the riblet on the prevention of the local scour decreases as time goes.
We have attempted to add not single riblet but many riblets to the pier in order to improve the effect of the riblet on the local scour and studied the characteristics of the local scour experimentally. It is found in this study that the pier having the riblets under the sand bed surface is most effective for the local scour.