Theoretical Foundation of Rapid Distortion Theory on Transversely Sheared Mean Flows

• Main Author: Marvin E. Goldstein
• Format: Article
• Language: English
• Published: MDPI AG 2020-04-01
• Series: Fluids
• Subjects: turbulent flow; Rapid Distortion Theory; compressible flow; aeroacoustics; shear flow
• Online Access: https://www.mdpi.com/2311-5521/5/2/62

The focus of this paper is on Rapid Distortion Theory on transversely sheared mean flows, which is often used to investigate turbulence-solid surface interactions. The main purpose of the paper is to bring together and present in a consistent fashion a general theory that has been developed in several different papers that have been published in the Journal of Fluid Mechanics. The equations for the unsteady pressure and velocity flections (which decouple from the entropy fluctuations) are rewritten in terms of a gauge function in order to obtain expressions that involve two arbitrarily convected quantities. A pair of very general conservation laws are used to derive upstream boundary conditions that relate these quantities to the actual physical variables. The entropy fluctuations can be determined after the fact once the solutions for the pressure and velocity fluctuations are known. The result involves a third arbitrary convected quantity that is equal to the entropy fluctuations at upstream infinity and can, therefore, be specified as an additional upstream boundary condition. A secondary purpose of the paper is to summarize a number of applications of the theory that have also appeared in the literature and show how they compare with an experiment.