Transition in high-speed free shear layers

The laminar free-shear layers considered in the study are formed by combinations of the velocities and momentum thicknesses of two adjacent parallel flows. Transition in wakes, pure free-shear layers of the Chapman type, and separate and partition flows are discussed. A stability-transition connection is emphasized, and it is suggested that a recurring deficiency in some stability calculations is the use of overly simplified laminar profiles. It is also noted that physical principles can be used for estimating the transition location or providing the factors affecting it. One such approach, a threshold theory, is discussed by way of example.