Two-Particle Dispersion in Model Velocity Fields

Abstract

We consider two-particle dispersion in a velocity field, where the relative two-point velocity scales according to $v^2(r)\propto r^{\alpha }$ and the corresponding correlation time scales as $\tau (r)\propto r^{\beta }$, and fix $\alpha =2/3$, as typical for turbulent flows. We show that two generic types of dispersion behavior arize: For $\alpha /2+\beta <1$ the correlations in relative velocities decouple and the diffusion approximation holds. In the opposite case, $\alpha /2+\beta >1$, the relative motion is strongly correlated. The case of Kolmogorov flows corresponds to a marginal, nongeneric situation.

4 pages, 4 figures, Latex

References in corpus (2)

• Intermittency in passive scalar advection
• Relative dispersion in fully developed turbulence: from Eulerian to Lagrangian statistics in synthetic flows

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