  In this paper 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. By using direct numerical
simulations, we show that the refined Kolmogorov similarity is broken and a new
form of similarity is observed, in agreement to previous results obtained in
turbulent boundary layers. As a consequence, the intermittency of velocity
fluctuations increases with respect to homogeneous and isotropic turbulence. 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.
