INVESTIGATION OF ROUGH BOTTOM BOUNDARY LAYER UNDER IRREGULAR WAVES

Abstract

Most of investigations on bottom boundary layer are for sinusoidal waves. In this study, flow properties in bottom boundary layer under irregular waves has been investigated from experimental data for rough bed condition. A method has been proposed to calculate instantaneous turbulent bottom shear stress from the variation in free stream velocity under irregular waves for rough bed condition. Instantaneous free stream velocity and a friction factor for significant wave or each waves included irregular wave have been introduced. Instantaneous bottom shear stress computed by the proposed method has been compared with experimental data. Proposed method presents a good agreement and has been found to be very convenient to use from the viewpoint of practical application.