Effect of Different Compositions in Unsubmerged L-head Groynes to Mean and Turbulent Flow Characteristics

Abstract

L-head groynes are extensively used for river bank protection, therefore encouraging the present study for the comparison of the near-bed turbulent flow characteristics among different compositions of L-head groynes. The turbulence characteristics near to the bed are needed to explore the turbulent structures fluctuations to achieve structure’s safety assurance for bank protection work; and their comparison can be used to utilize the efficiency of groynes according to the practical field requirement. In the present study, the mean and turbulent flow characteristics such as three-dimensional velocity distribution, turbulent Reynolds stresses, turbulent kinetic energy, and bed shear stress have been compared by conducting 36 experiments with varying compositions of groyne. With the increase in the groyne’s configuration and constriction ratio; the magnitude of the vertical Reynolds stress, turbulent kinetic energy and the bed shear stress decrease accordingly within the wake zone. Application of higher constriction to the flow creates comparative increased transverse and the vertical velocity region at the upstream of the groyne, leading to a state of maximum risk to the groyne’s foundation. The dominancy of horizontal turbulent mixing compared to vertical turbulent mixing; and the amplification of bed shear stress around the groyne are explored.