Scaling laws and intermittency in homogeneous shear flow

In this article we discuss the dynamical features of intermittent fluctuations in homogeneous shear flow turbulence. In this flow the energy cascade is strongly modified by the production of turbulent kinetic energy related to the presence of vortical structures induced by the shear. As a consequence, the intermittency of velocity fluctuations increases with respect to homogeneous and isotropic turbulence. By using direct numerical simulations, we show that the refined Kolmogorov similarity is broken and a new form of similarity is observed, in agreement with previous results obtained in turbulent boundary layers. We find here that the statistical properties of the energy dissipation are practically unchanged with respect to homogeneous isotropic conditions, while the increased intermittency is entirely captured in terms of the new similarity law. (C) 2002 American Institute of Physics.