Experimental Studies for Shear Stress and Local Scour on the Bed with Plants

Abstract

The shear stress acting on the bed around vertical circular cylinders and artificial seaweeds installed in a wave flume with multiple rows are measured by using a shear stress sensor. The sand movement and local scour around these plant models are also observed. The close agreement between the time variation of shear stress measured by the shear sensor and the estimated values from the theoretical values of boundary layer equation in harmonic flow with laminar flow are obtained in the case of regular wave with smooth bed. The shear stress on the smooth bed with vertical circular cylinders increase compare to the shear stress on the bed without circular cylinders. The sand in side of these plant models move mainly in the direction of shoreline. These phenomena may be due to the disappearance of ripple on the sand bed with circular cylinders.