Large eddy simulation of flows in some curved flumes

The curvature of the flow in river bends and in curved flumes leads to secondary flow normal to the main flow direction. Reynolds averaged numerical simulations (RANS), e.g. by k-epsilon models or RSM, fail to reproduce sufficiently the sometimes complicated secondary flow pattern observed. In the computation of the flow in a rotating annular flume both the separation of the flow from the outside wall and the turbulence energy are not reproduced correctly. For the river bend flow the reproduction of a second counter rotating secondary flow cell proved problematic. Recently executed large eddy simulations (LES) gave better results. The computed main flow, but also the secondary flow and the turbulence energy in the rotating annular flume deviate hardly from the measurements. For the river bend a good reproduction of the main flow and the secondary flow is obtained, showing the second counter rotating secondary flow cell.