Study of Turbulent Flow Structure and Qualitative Investigation of Sediment Entering Lateral Intake in River Bend Using 3D Numerical Model

In this paper the 3D turbulent flow field through lateral intake in a 180 degree curved channel is numerically simulated using the RSM turbulence model as implemented in the Fluent software and the VOF technique is used to model the free surface at junction region and along the intake system. The used turbulence model and the VOF technique are able to predict the velocity field and furthermore the simulated water surface profiles have good agreement with measurements.Results of simulations show that in this case, similar to the lateral diversion in the straight channel, a separation zone forms along the intake and moreover due to the presence of the strong lateral flow, a stagnation zone forms along the inner bank of the main channel, downstream of the junction region. The flow field through the intake is so that the separation zone and the oblique near bed stream lines cause the formation of a wedge like zone at intake entrance. Investigation of previous experimental observations shows that this zone coincides with a triangular shaped sediment point bar in movable bed case.The depth varying structure of the dividing stream surface is completely different from the lateral diversion in the straight channel and this difference highlights the role of secondary flows in curved channels in controlling the sediment entry to the lateral intakes.