Accession Number : ADA309955

Title :   A Study of Compressible Turbulence.

Descriptive Note : Final rept. 25 Sep 93-24 Mar 96,

Corporate Author : NIELSEN ENGINEERING AND RESEARCH INC MOUNTAIN VIEW CA

Personal Author(s) : Childs, Robert E. ; Reisenthel, Patrick H.

PDF Url : ADA309955

Report Date : 29 MAY 1996

Pagination or Media Count : 32

Abstract : Numerical simulations have been used to study the effects of compressibility on turbulence. Statistical and structural changes in turbulence are observed in both mixing layers and boundary layers due to dynamical compressibility effects. In mixing layers, the coherent large-scale vortices which dominate turbulent momentum transport change from being roughly spanwise at low convective Mach numbers to being oblique at elevated convective Mach numbers, roughly Mc > 0.7. Simulations of boundary layers have been performed up to M = 5, for adiabatic wall and mean-isothermal conditions; the latter is achieved by the computational artifice of deleting the mean dissipative heating. The mean-isothermal case experiences none of the classical compressible boundary layer effects, which are due to variable properties, and it increases the effective Mach number by lowering the near-wall sound speed. Numerous changes are observed in turbulent statistics and structures of the mean-isothermal flow, relative to low-speed flows. Perhaps the most striking change occurs in the structure of viscous sublayer streaks. The streaks are sinuous at low Mach numbers, but they become straighter at elevated Mach numbers. Features of the dilatation suggest that dynamical compressibility effects cause these changes.

Descriptors :   *TURBULENCE, *COMPRESSIBLE FLOW, *BOUNDARY LAYER FLOW, ALGORITHMS, COMPUTERIZED SIMULATION, OPTIMIZATION, TAYLORS SERIES, TIME SERIES ANALYSIS, ACCURACY, TURBULENT FLOW, VORTICES, COMPUTATIONAL FLUID DYNAMICS, ERROR ANALYSIS, INTERPOLATION, MACH NUMBER, CONVECTION(HEAT TRANSFER), NAVIER STOKES EQUATIONS, FREE STREAM, VISCOUS FLOW, VISCOSITY, AERODYNAMIC HEATING, SKIN FRICTION, RUNGE KUTTA METHOD, MOMENTUM TRANSFER, JET MIXING FLOW, ADIABATIC GAS FLOW.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE