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

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 configuration introduced by Campagne et al. (G. Campagne, J.B. Cazalbou, L. Joly, and P. Chassaing, Direct numerical simulation of the interaction between unsheared turbulence and a free-slip surface, in ECCOMAS CFD 2006, P. Wesseling, E. Onate, and J. Periaux eds., TU Delft, The Netherlands, 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 the 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 ...