Author(s): Richard Mcsherry, Thorsten Stoesser, Roger A. Falconer
Linked Author(s): Richard McSherry
Keywords: Open channel flow, double averaging, turbulent kinetic energy, large eddy simulation.
Abstract: Results from a large eddy simulation of open channel flow over a rough bed with self-affine fractal properties are presented. The surface is considered to be broadly representative of rough bed forms that occur naturally in streams and rivers. The double averaging methodology is applied to enable analysis of the vertical distribution of turbulent and form-induced stresses throughout the depth. It is observed that the form-induced stress is a significant contributor to the streamwise momentum balance in the roughness sub-layer, reaching a peak value equal to approximately 16% of the peak shear stress. Particular attention is given to the distribution of the TKE budget. Important similarities with results from studies of flows over gravel beds, both numerical and experimental, are observed. A relatively large contribution due to wake production (approximately 15% of the peak production due to mean shear) is observed, which is in contrast to gravel bed studies
Year: 2017