PREDICTION OF TURBULENT-FLOW OVER ROUGH ASYMMETRICAL BED FORMS

This paper is concerned with a numerical investigation of the turbulent flow over a train of immobilized two-dimensional asymmetric bed forms. The results from a differential second moment (DSM) closure turbulence model, together with two simpler eddy-viscosity based models, are compared with experimental data. The DSM model is then used to calculate the drag coefficient over bedforms of varying steepness, and the result is compared with a number of empirical formulas that have previously been proposed Finally, the partitioning of the total drag into form drag and skin friction contributions as a function of bedform steepness is investigated.