Flow and sediment transport across oblique channels

A 3D numerical investigation of flow across channels aligned obliquely to the main flow direction has been conducted. The applied numerical model solves the Reynolds-averaged Navier-Stokes equations using the k-ε model for turbulence closure on a curvilinear grid. Three momentum equations are solved, but the computational domain is 2D due to a uniformity along the channel alignment.

Two important flow features arise when the flow crosses the channel: (i) the flow will be refracted in the direction of the channel alignment. This may be described by a depth-averaged model. (ii) due to shear in the velocity profile secondary flow will be introduced. This can only be described by a 3D approach.

The secondary flow will cause a horizontal displacement of streamlines over the vertical. Only by capturing the latter flow feature the direction and magnitude of the bed shear stress are well estimated. Results of the numerical model are compared to existing experimental data.