Extreme fluctuations of the relative velocities between droplets in turbulent airflow

Abstract

We compare experiments and direct numerical simulations to evaluate the accuracy of the Stokes-drag model, which is used widely in studies of inertial particles in turbulence. We focus on statistics at the dissipation scale and on extreme values of relative particle velocities for moderately inertial particles (St < 1). The probability distributions of relative velocities in the simulations were qualitatively similar to those in the experiments. The agreement improved with increasing Stokes number and decreasing relative velocity. Simulations underestimated the probability of extreme events, which suggests that the Stokes drag model misses important dynamics. Nevertheless, the scaling behavior of the extreme events in both the experiments and the simulations can be captured by the same multi-fractal model.

7 pages, 9 figures. Also published in Physics of Fluid (Letters)

References in corpus (6)

• The multifractal nature of turbulent energy dissipation
• Heavy particle concentration in turbulence at dissipative and inertial scales
• Caustic activation of rain showers
• Sling effect in collisions of water droplets in turbulent clouds
• Observation of the sling effect
• Relative velocities of inertial particles in turbulent aerosols

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