Behavior of turbulent boundary layers after a strong disturbance

The effect of strong disturbances caused by sudden changes in wall roughness was investigated both experimentally and theoretically. Experimental results show the flow to have a three layer structure, each of these layers being characterized by a different scaling behavior. Calculations based on a model show that the experimentally determined flow structure can only be partially predicted. An integral method is presented for calculating the turbulent boundary layer after a jump in wall roughness; it takes the three layer structure into account and involves an entrainment concept. The results obtained in this way for the magnitude of the various flow parameters are good.