Turbulent spots in a compressible boundary-layer flow

Abstract

Direct simulation of an isolated turbulent spot in a compressible isothermal wall boundary-layer flow has been performed. A bypass transition scenario at Mach 2,4 and 6 is considered. The flow field associated with the transitional and turbulent spots is studied in detail, with results in broad agreement with previous experimental work. The evolved spots are found to have an arrowhead shaped front with a leading edge overhang, followed by a turbulent core and a calmed region at the rear interface. The lateral spreading of the spot is found to decrease substantially with the flow. Evidence for a supersonic (Mack) mode is found in the Mach 6 case: spanwise-coherent structures are observed under the spot overhang region. © 2006 Springer.