VISCOSITY AND FORCE CORRECTIONS INDUCED BY THE ELIMINATION OF SCALES OF MOTION IN RANDOMLY FORCED TURBULENCE

Systematic scale elimination in the description of randomly forced tur bulence leads to a hierarchy of new terms in the dynamical equations. We consider two of these terms: the viscosity and random forcing corre ctions. We show how these corrections can be estimated using direct nu merical simulation data of homogeneous isotropic turbulence. In the ca se of hyperviscous dissipation, the energy spectrum shows, between the inertial range and the dissipative range, an intermediate range chara cterized by a reduction of the eddy viscosity and a correction to the forcing representing a backward energy flux.