Effect of a vegetation patch on turbulent channel flow

Abstract

The effect of a vegetation patch (VP) on the flow and turbulence characteristics is studied. Two turbulence models are used to simulate patch presence. Numerical results for both mean and turbulence flow characteristics are compared with available measurements to assess the performance of these models for dense and sparse submerged VPs. The mechanisms which control the turbulent development inside the VP are also discussed, and the patch effect on the downstream flow and turbulence is assessed. The results indicate that the patch length and the vegetation density dominate the turbulent development. An increase in the vegetation density causes acceleration of the development of flow velocity and turbulence characteristics inside the patch and increases the channel length downstream of the patch where its effect is significant. Also areas with increased and decreased values of bed shear stresses are observed at the initial part and at the end of the patch, respectively.