Whither the Zeroth Law of Turbulence?

Experimental and numerical studies of incompressible turbulence suggest that the mean dissipation rate of kinetic energy remains constant as the Reynolds number tends to infinity (or the non-dimensional viscosity tends to zero). This anomalous behavior is central to many theories of high-Reynolds-number turbulence and for this reason has been termed the "zeroth law". Here we report a sequence of direct numerical simulations of incompressible Navier-Stokes in a box with periodic boundary conditions, which indicate that the anomaly vanishes at a rate that agrees with the scaling of third-moment of absolute velocity increments. Our results suggest that turbulence without boundaries may not develop strong enough singularities to sustain the zeroth law.