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Intermittent particle distribution in synthetic free-surface turbulent flows

2008; American Physical Society; Volume: 77; Issue: 6 Linguagem: Inglês

10.1103/physreve.77.066304

1550-2376

Lauris Ducasse, Alain Pumir,

Fluid Dynamics and Turbulent Flows

Tracer particles on the surface of a turbulent flow have a very intermittent distribution. This preferential concentration effect is studied in a two-dimensional synthetic compressible flow, both in the inertial (self-similar) and in the dissipative (smooth) range of scales, as a function of the compressibility $\mathcal{C}$. The second moment of the concentration coarse grained over a scale $\mathit{r}$, $⟨{n}_{r}^{2}⟩$, behaves as a power law in both the inertial and the dissipative ranges of scale, with two different exponents. The shapes of the probability distribution functions of the coarse-grained density ${\mathit{n}}_{\mathit{r}}$ vary as a function of scale $\mathit{r}$ and of compressibility $\mathcal{C}$ through the combination $\mathcal{C}/{r}^{\ensuremath{\kappa}}$ $(\ensuremath{\kappa}\ensuremath{\simeq}0.5)$, corresponding to the compressibility, coarse grained over a domain of scale $\mathit{r}$, averaged over Lagrangian trajectories.