The Role of Waves on Flow Resistance in High-speed Shear Flow

The role of waves on flow resistance in high-speed shear were examined by numerical simulation over a range of convective Froude numbers from sub-critical to super-critical flow. At low convective Froude numbers, the exchanges of mass and momentum across the shear flow are dominated by a string of eddies. The coalescence and merging between the neighboring eddies decide the mixing rate. At higher convective Froude numbers on the other hand, the exchanges are decided by the radiation of the gravity waves and the development of the eddy-shocklets. The growth in width of the sub-critical shear flow was nearly the same as the super-critical flow. The nature of mass and momentum exchanges by the eddies were fundamentally different from the exchanges by the shocklets.