The Effects of Boundary Turbulence on Canyon Flows Forced by Periodic Along-Shelf Currents

Abstract Previous laboratory experiments and associated numerical models of laminar flows forced by oscillatory, along-shelf background currents are extended to include some of the effects of boundary-generated turbulence. The experiments are conducted in the 13-m-diameter rotating-flow facility in Grenoble, France. Two pairs of case studies, one at a large forcing velocity (designated as FAST) for which the boundary layers are fully turbulent during part of the flow cycle and one at relatively smaller forcing (SLOW) for which transitional boundary layers are operative at the higher speeds of the background flow, are conducted. Smooth and artificially roughened boundaries are considered, respectively, for each of these pairs. Phase-averaged and time-mean velocity, vertical vorticity, and horizontal divergence fields are found to be qualitatively similar to those of previous laminar experiments. The similarities in the time-mean fields are that (i) within the canyon they are dominated by cyclonic vorticity...