The roles of shear and cross-correlations on the fluctuation levels in simple stochastic models
- Princeton University, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States)
Highly simplified models of random flows interacting with background microturbulence are analyzed. In the limit of very rapid velocity fluctuations, it is shown rigorously that the fluctuation level of a passively advected scalar is not controlled by the rms shear. In a model with random velocities dependent only on time, the level of cross-correlations between the flows and the background turbulence regulates the saturation level. This effect is illustrated by considering a simple stochastic-oscillator model, both exactly and with analysis and numerical solutions of the direct-interaction approximation. Implications for the understanding of self-consistent turbulence are discussed briefly. (c) 2000 American Institute of Physics.
- OSTI ID:
- 20215727
- Journal Information:
- Physics of Plasmas, Vol. 7, Issue 4; Other Information: PBD: Apr 2000; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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