DNS of compressible turbulent boundary layers and assessment of data/scaling-law quality. (12th March 2018)

• Record Type: Journal Article
• Authors: Wenzel, Christoph; Selent, Björn; Kloker, Markus; Rist, Ulrich
• Is Part Of: Journal of fluid mechanics. Volume 842(2018)
• Page Start: 428
• Page End: 468
• Publication Date: 2018-03-12
• Subjects: compressible boundary layers, -- compressible turbulence, -- turbulent boundary layers; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2018.179
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract : A direct-numerical-simulation study of spatially evolving compressible zero-pressure-gradient turbulent boundary layers is presented for a fine-meshed range of Mach numbers from 0.3 to 2.5. The use of an identical set-up for all subsonic and supersonic cases warrants proper comparability and allows a highly reliable quantitative evaluation of compressible mean-flow scaling laws and the settlement on a commonly accepted compressible mean-flow velocity profile in the considered Mach and Reynolds number range. All data are compared to the literature data-base where significant data scattering can be observed. The skin-friction distribution was found in excellent agreement with the prediction by the van Driest-II transformation. Contrary to the prevailing appraisal, the wake region of the mean-velocity profile is observed to scale much better with the momentum-thickness Reynolds number calculated with the far-field-viscosity than with the wall-viscosity. The time-averaged velocity fluctuations, density-scaled according to Morkovin's hypothesis, are found to be noticeably influenced by compressibility effects in the inner layer as well as in the wake region. Allowing wall-temperature fluctuations affects neither the density nor velocity fluctuations.