Performance of a turbulence model for flows in partially vegetated open channels

Abstract

A non-linear k-ε model coupled with a vegetation model has been applied to three turbulent flows in partially vegetated open channels to scrutinize its performance. Three test cases include flow in a straight rectangular channel with vegetation belts along both sides of the channel and flows in a compound channel with different emergent vegetation zones over a floodplain, where experimental data have been obtained by the authors. Comparison with the experimental results demonstrates that the non-linear k-ε model can reasonably captures secondary flows of the second kind and a row of large vortices along the interface between main channel and vegetated zones, which the standard k-ε model fails to produce. The calculated results are found to show fairly good agreement with the measurements in terms of mean streamwise velocity, secondary currents of the second kind and Reynolds shear stresses components.