spectral les of turbulent flows over bluff bodies: from the ... - BBAA VI

Minguez Matthieu, Pasquetti Richard and Serre Eric3.2.1 Mean velocity and stress tensor components profilesThe mean profiles of the streamwise velocity and components of the stress tensor have beenaveraged both in time and in the z-spanwise homogeneous direction. Results obtained with thestandard SVV-LES and the SVV-NW approaches are plotted in Figure 2 and 3, together withthose of the experimental and numerical reference studies [13, 20].21.81.6Exp LynLES Rodi UK2SVV−LES with smoothingSVV−LES + NW21.81.6Exp LynLES Rodi UK2SVV−LES with smoothingSVV−LES + NW1.41.4y1.2y1.2110.80.80.60.6a0.4−0.4 −0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6Ub0.4−0.4 −0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6U21.81.6Exp LynLES Rodi UK2SVV−LES with smoothingSVV−LES + NW21.81.6Exp LynLES Rodi UK2SVV−LES with smoothingSVV−LES + NW1.41.4y1.2y1.2110.80.80.60.6c0.4−0.4 −0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6Ud0.4−0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6UFigure 2: y-profiles of the mean streamwise velocity U =< u x > in the boundary layer of the square cylinder atx = −0.375D (a), x = −0.125D (b), x = 0.25D (c) and x = 0.5D(d), obtained with the standard and improvedSVV-LES approaches. Comparisons with the LES of Rodi et al. [20]) and with the experiments of Lyn [13].Present results are globally in good agreement with the experimental data despite of a coarserresolution than in Rodi et al. [20]. The NW treatment considerably improves the present LESresults.In near-wall region, the SVV-NW simulations give a satisfactory estimation of the extremumof the mean streamwise velocity U as well as its location, within the boundary layer, see Figure2. The results are even better than those provided, 15 years ago, by Rodi et al. [20] whichtend to overestimate the maximum of U. The recirculation zone on the cylinder is particularlywell described, with a maximal relative error of about 10% with respect to the first experimentalmeasurement point from the wall in Figure 2b). Within the shear layer generated by the juxtapositionof the recirculation zone and the external velocity field (at y ≃ 0.8), all the LES resultsoverestimate the streamwise velocity in an intermediate region of height ∆y ≃ 0.5. This ten-7