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Direct numerical simulation of unsheared turbulence diffusing toward a free-slip or no-slip surface

Bodart, Julien and Cazalbou, Jean-Bernard and Joly, Laurent Direct numerical simulation of unsheared turbulence diffusing toward a free-slip or no-slip surface. (2010) Journal of Turbulence, vol. 11 (n° 48). pp. 1-18. ISSN 1468-5248

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Official URL: http://dx.doi.org/10.1080/14685248.2010.521632

Abstract

The physics involved in the interaction between statistically steady, shearless turbulence and a blocking surface is investigated with the aid of direct numerical simulation. The original conguration introduced by Campagne et al. [ECCOMAS CFD 2006] serves as the basis for comparing cases in which the blocking surface can be either a free-slip surface or a no-slip wall. It is shown that in both cases, the evolutions of the anisotropy state are the same throughout the surface-influenced layer (down to the surface), despite the essentially different natures of the inner layers. The extent of the blocking effect can thereby be measured through a local (surface) quantity identically defined in the two cases. Examination of the evolution and content of the pressure-strain correlation brings information on the mechanisms by which energy is exchanged between the normal and tangential directions: In agreement with an earlier analysis by Perot and Moin [J. Fluid Mech. 295 (1995)], it appears that the level of the pressure strain correlation is governed by a splat/antisplat disequilibrium which is larger in the case of the solid wall due to viscous effects. However, in contradiction with the latter, the pressure-strain correlation remains as a signicant contributor to both Reynolds-stress budgets; it is argued that the net level of the splat/antisplat disequilibrium is set, in the first place, by the normal-velocity skewness of the interacting turbulent field. The influence of viscous friction on the intercomponent energy transfer at the solid wall only comes in the second place and part of it can also be measured by the skewness. The remainder seems to originate from interactions between the strain field and ring-like vortices in the vicinity of the splats.

Item Type:Article
Audience (journal):International peer-reviewed journal
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Institution: Université de Toulouse > Institut Supérieur de l'Aéronautique et de l'Espace - ISAE
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Deposited By: J.-B. Cazalbou
Deposited On:02 Sep 2010 07:10

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