Scaling of structure functions in homogeneous shear-flow turbulence

We apply spectral dynamics and non-Gaussian statistical model of velocity difference to study the scaling of structure functions in homogeneous shear-flow turbulence. Let L(S) be the shear length scale and eta the viscous scale. It is found that, when L(S)/eta is finite, due to a combined effect of viscosity and mean shear, the scaling deviates from normal scaling, and the deviation increases as L(S)/eta decreases. In the presence of a strong shear (L(S)/eta<100), the deviation is substantially larger than the prediction of typical intermittency models, in agreement with recent experiments. As L(S)/eta-->infinity, the normal scaling is valid in the inertial range where viscous and shear effects are negligible.