Laboratory investigation of flow and turbulent characteristics around permeable and impermeable groynes in a strongly curved meandering channel

Abstract

ABSTRACT The study investigates the role of cocolog, an eco-friendly material, as groyne, in protecting the river banks in meandering channels. Laboratory experiments were conducted to compare the flow pattern and sediment dynamics in a mobile-bed meandering channel for cocolog (permeable) and impermeable groynes. It is observed that as the permeability increases, the vertical and transverse velocities are seen to be reduced in the groyne fields. The results also indicate that places of maximum scour depth display amplified velocity, turbulent intensity and turbulent kinetic energy. However, considerable reduction in these characteristics is being observed in the case of permeable groynes that have densities varying between 140 and 160 kg/m3. The eroded volume is seen to be reduced by 60% for permeable groynes of medium density compared to the tests done without groynes. Also impermeable groynes exhibit a wider distribution of the maximum values for scour depth, turbulence intensity and turbulent kinetic energy than that of permeable groynes. It is found that the cocolog groynes with suitable density (or permeability) can perform best in meandering channels by dampening the velocity and turbulence of the groyne fields.