Renormalization group, operator product expansion and anomalous scaling in models of passive turbulent advection

Abstract

The field theoretic renormalization group is applied to Kraichnan's model of a passive scalar quantity advected by the Gaussian velocity field with the pair correlation function $\propto \delta (t-t^{\prime })/k^{d+\epsilon }$. Inertial-range anomalous scaling for the structure functions and various pair correlators is established as a consequence of the existence in the corresponding operator product expansions of ``dangerous'' composite operators (powers of the local dissipation rate), whose {\it negative} critical dimensions determine anomalous exponents. The latter are calculated to order ${\epsilon }^3$ of the $\epsilon$ expansion (three-loop approximation).

4 pages