3D RANS computations of open channel flows with a sharp bend

This paper describes a 3D computation of an open channel flow with a sharp bend. The flow with a bend is characterized by generation of secondary current of the first kind due to the local unbalance of the centrifugal force and lateral pressure gradient. Since a non-linear k- model combined with a coarser computational grid is applied for the turbulence computation, the present method becomes much less expensive than LES approaches. The computation was performed under the same conditions of the laboratory test conducted by Blanckaert (2002). The present computation could capture qualitatively the main cell of the secondary current as well as a small cell called “outer-bank cell”. The agreement of profiles of velocities and Reynolds stresses is also shown to be satisfactorily. Considering the computational efficiency, it is pointed out that the present RANS approach is a practical tool for prediction of open channel flows with a sharp bend.