The Numerical Decomposition of Turbulent Fluctuations in a Compressible Boundary Layer |
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Authors: | Stanislav G Borodai Robert D Moser |
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Institution: | (1) Department of Theoretical and Applied Mechanics, University of Illinois, Urbana, IL 61801, U.S.A., US |
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Abstract: | In many flows the turbulence is weakly compressible even at large Mach number. For example, in a compressible boundary layer
Ma<5, the differences relative to an incompressible boundary layer understood as being caused by density variations that accompany
variations temperature across the layer. Turbulent fluctuations in a boundary layer are therefore expected to be dominated
by the effects nonconstant temperature, and low Mach number theories in which fluctuations are not dominant should be applicable
to the fluctuating field. However, the analysis of compressible boundary layer DNS data reveals presence of significant acoustic
fluctuations. To distinguish acoustic and thermal effects, a numerical decomposition procedure compressible boundary layer
fluctuations is applied to determine the and nonacoustic fluctuations. Except for very near the wall, where decomposition
procedure is not valid, it is found that the fluctuations are only weakly coupled to the acoustic fluctuations at numbers
as high as 6.
Received 13 March 2000 and accepted 21 May 2001 |
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