A simple model for low-frequency unsteadiness in shock-induced separation

• Published in: Journal of fluid mechanics Vol. 629; pp. 87 - 108
• Main Authors: PIPONNIAU, S., DUSSAUGE, J. P., DEBIÈVE, J. F., DUPONT, P.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 25.06.2009; Cambridge University Press (CUP)
• Subjects: Boundary layer and shear turbulence; Boundary layers; Compressible flows; shock and detonation phenomena; Engineering Sciences; Exact sciences and technology; Fluid dynamics; Fluid mechanics; Fluids mechanics; Fundamental areas of phenomenology (including applications); Mechanics; Physics; Shock waves; Shock-wave interactions and shock effects; Turbulent flows, convection, and heat transfer; Shock waves; Turbulent flow; Flow separation; Separation bubble; Modelling; Velocity distribution; Interactions; Low frequency; Boundary layers; Wave reflection
• ISSN: 0022-1120; 1469-7645
• DOI: 10.1017/S0022112009006417

A model to explain the low-frequency unsteadiness found in shock-induced separation is proposed for cases in which the flow is reattaching downstream. It is based on the properties of fluid entrainment in the mixing layer generated downstream of the separation shock whose low-frequency motions are related to successive contractions and dilatations of the separated bubble. The main aerodynamic parameters on which the process depends are presented. This model is consistent with experimental observations obtained by particle image velocimetry (PIV) in a Mach 2.3 oblique shock wave/turbulent boundary layer interaction, as well as with several different configurations reported in the literature for Mach numbers ranging from 0 to 5.