Velocity Profiles in Smooth and Rough Open Channel Flows

Abstract

Analysis of different flows is influenced by the different flow parameters. An experimental investigation concerning the longitudinal velocity distribution and depth averaged velocity distribution in an open channel flow has been conducted. Four sets of roughness have been chosen to investigate the effect of roughness on the prediction of the vertical velocity profile in an open channel flow. Vertical velocity profile depends on upon the geometric surface and hydraulic conditions. From the critical review of various researchers, the dip phenomenon depends on the small aspect ratio. Dip phenomenon is the phenomenon in which the maximum velocity occurs below the surface of the water. It is an important phenomenon which influences the vertical velocity profiles. Dip correction factor is found to depend on upon the roughness of the channel and other geometry and flow conditions. A laboratory investigation has been done to evaluate the dip correction factor and to study the variation of dip correction factor due to roughness changes. Keeping the geometry constant, roughness has been varied to study the effect of dip phenomenon. A multi-linear regression has been done to develop a mathematical expression for the smooth and rough channel. The comparison is found to provide more accurate velocity profiles as compared to Yang et al. (2004) method. The present work can be used to predict the longitudinal velocity profiles of a rough open channel flow. The experimental research work has been well compared with two numerical hydrodynamic tools i.e., CES (Conveyance Estimation System) and SURFER software.