Decay of Boundary-Layer Turbulence in Near Wake of a Slender Body

Abstract

A theoretical study of the decay of the fluctuating velocities in the supersonic near wake expansion of boundarylayer turbulence is presented. A model based on linear theories is utilized to predict the change in fluctuation levels and turbulent scale sizes. The effect of the compressibility of the mean flow is included, and mean properties are calculated from method of characteristics solutions. The validity of linear theory is examined, and an analysis of the decay of eddy turbulence associated with the vorticity field is presented. Results indicate that the decay rate is strongly dependent upon proper specification of the anisotropic boundary-layer turbulence. Results consistent with data for the turbulence decay in the near wake of a slender wedge are obtained when a realistic choice of the boundary-layer turbulent energy spectrum and velocity fluctuation levels is made.