Dissipation in Turbulent Flows

This article reviews evidence concerning the cornerstone dissipation scaling of turbulence theory: epsilon = C epsilon U3/L, with C-epsilon = const., epsilon the dissipation rate of turbulent kinetic energy U-2, and L an integral length scale characterizing the energy-containing turbulent eddies. This scaling is intimately linked to the Richardson-Kolmogorov equilibrium cascade. Accumulating evidence shows that a significant nonequilibrium region exists in various turbulent flows in which the energy spectrum has Kolmogorov's -5/3 wave-number scaling over a wide wave-number range, yet C-epsilon similar to Re-I(m)/Re-L(n), with m approximate to 1 approximate to n, Re-I a global/inlet Reynolds number, and Re-L a local turbulence Reynolds number.