Numerical Study of Flow in Skewed Compound Channel Using k-ε Turbulence Model

In this paper, an effort was made to model velocity and boundary shear stress distributions in a compound channel with skewed floodplains. A three-dimensional computational fluid dynamics model (CFD) was used to solve the time-averaged Navier-Stokes equations. Based on the k-epsilon turbulence model, the ANSYS-CFX software was used to evaluate the velocity, bed shear stress distributions, and secondary flow circulations in a skewed compound channel with skew angle of 5.1 degrees and different overbank flow depths. The results of numerical modelling at two selected sections were then compared to the published experimental data. The study shows that the k-epsilon turbulence model is able to evaluate the flow field in the skewed compound channel fairly well. The numerical modelling also reveals the existence of the helical secondary flow with the horizontal axis in the main channel which created by the mass exchange between the converging floodplain and the main channel.