We present the results of a numerical investigation of three-dimensional homogeneous and isotropic turbulence, stirred by a random forcing with a power-law spectrum, $E_f(k)\sim k^{3-y}$. Numerical simulations are performed at different resolutions up to ${512}^3$. We show that at varying the spectrum slope $y$, small-scale turbulent fluctuations change from a forcing independent to a forcing dominated statistics. We argue that the critical value separating the two behaviors, in three dimensions, is $y_c=4$. When the statistics is forcing dominated, for $y<y_c$, we find dimensional scaling, i.e., intermittency is vanishingly small. On the other hand, for $y>y_c$, we find the same anomalous scaling measured in flows forced only at large scales. We connect these results with the issue of universality in turbulent flows.

• Received 6 October 2003

DOI:https://doi.org/10.1103/PhysRevLett.92.094503