Turbulence transport in the presence of a macroscale gradient

In the absence of kinetic energy production, the intermediate asymptotics of the turbulent shear-free mixing layer is considered. By means of a theoretical analysis based on the use of the two-point correlation equations and their intermediate-similarity solutions, we examine the following two results obtained via numerical experiments on the interaction between different decaying homogeneous and isotropic turbulences: \begin{enumerate} \item mixing is highly intermittent for shear-free decaying homogeneous isotropic interacting flows with kinetic-energy ratios far from unity in contrast to a Gaussian asymptotic state, and \item the intermittency increases/decreases when the kinetic-energy gradients and integral-scale gradients are aligned/opposite. \end{enumerate}