Large-Eddy Simulation Of Turbulent Separated Flow Over Rough Hills

Large-eddy simulations (LES) have been performed ofneutral turbulent flow over two-dimensional ridges steepenough to cause separation. Both periodic and isolated ridges havebeen considered. The results are compared with wind-tunnel observations and with the predictions of various turbulence closure models.For the periodic case the LES results are qualitatively reasonable,although the depth of the separated region appears to besensitive to the use of a distributed drag near the lower boundary.The isolated ridge results compare very favourably with the experimentaldata, with the LES performance appearing to be at least as good as that ofthe closure models.