Development of Two-layered model for compound open-channel flow

Abstract

Present study deals with the development of two-dimensional two-layered model for straight compound open-channel flow using Smagorinsky-based subgrid-scale turbulence model, based on large eddy simulation approach. The two-layer depth averaged governing equations are solved using finite volume method based on MacCormack predictor-corrector explicit scheme. Model results for symmetric and asymmetric straight compound channel flows are verified with the available numerical and experimental data. Variations of flow variables in symmetric and asymmetric straight compound channels in terms of shear stress distributions and spanwise and vertical velocities are analyzed at the horizontal interface between the lower layer and the upper layer. Spanwise and vertical velocities at the horizontal interface revealed the existence of horizontal vortices near the junction of the main channel and the floodplain where momentum exchange takes place. Further, the model result, showing the spanwise shear stresses distribution at the interface of symmetric and asymmetric compound channel, revealed the existence of peak shear stress near the channel junction. Sensitivity of the two important model parameters is also undertaken and their roles in longitudinal velocity distribution along the channel width are discussed.