Abstract

Turbulence energy transfer through scales is arguably one of the most central and important processes in turbulent flows. Much of turbulence theory and modelling over the past 70 years has been based on the Kolmogorov (1941) stationary cascade which implies a particular well-known scaling of the turbulence dissipation rate. However, accumulating evidence from laboratory experiments and, more recently, numerical simulations is pointing at a very different turbulence dissipation scaling in important regions of various turbulent flows. There are consequences for boundary-free turbulent shear flows such as self-similar turbulent wakes and jets because their growth rates are closely linked to the centreline turbulence dissipation scaling. These consequences include new turbulent mean flow scalings with streamwise distance, and consequences concerning entrainement through the turbulent/non-turbulent interface. Direct Numerical Simulations of unsteady periodic turbulence suggest that the turbulence dissipation scalings are related to unsteady interscale energy transfer processes. Different dissipation scalings result from different types of unsteady interscale energy transfers.