Numerical evidence of a new similarity law in shear dominated flows

Recent theoretical results concerning the effect of shear on scaling laws in turbulence are discussed. DNS data for a turbulent channel flow and a homogeneous shear flow are used to investigate the statistical properties of turbulent fluctuations. As expected, the shear increases the level of intermittency of velocity increments. Instead, the statistical properties of the dissipation field remain similar to those of homogeneous isotropic turbulence. In fact, the increase of intermittency is found to be associated with the failure of the refined Kolmogorov similarity and the establishment of a new similarity law accounting for the prevailing role of the energy production related to the Reynolds stresses in mean shear. The relevance of these findings for eddy viscosity closures in LES of shear dominated flows is briefly outlined.