COMPUTATIONS ON MEANDERING COMPOUND OPEN CHANNEL FLOWS USING 3D URANS MODEL

Abstract

A meandering compound open channel flows show a complicated three-dimensional flow structures because of the combined effects of the secondary currents of the first kind, and the horizontal vortices at the junction between the main channel and the floodplain. The secondary current of the first kind is generated by the unbalance of the centrifugal force and the lateral pressure gradient. The horizontal vortices are generated due to the shear layer instability. Clarification of the flow is important for both flood control and river environment. URANS computations have more computational efficiency compared with LES or DNS. The applicability of 3D CFD model based on a URANS non-linear k-epsilon model was examined through the comparison with the experimental results by Sanjo et al, in which detailed steady and unsteady flow structures have been illustrated clearly through PIV measurement. The present URANS computations could reproduce the secondary flow patterns excellently. The horizontal vortex shedding observed in the experiment could also be captured though shape of the row of vortices was not replicated well.