Characterizing intense rotation and dissipation in turbulent flows

Lanterman, Daniel; Lathrop, Daniel P.; Zeff, Benjamin W.; McAllister, Ryan; Roy, Rajarshi; Kostelich, Eric J.

doi:10.1063/1.1821715

Cited by 3 publications

(1 citation statement)

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“…trajectories [9]. While the latter behavior is a matter of common experience, the interpenetration of trajectories has until now not been seen, except in a two-dimensional flow [10].…”

Section: Introductionmentioning

confidence: 99%

Observation of the sling effect

2013

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When cloud particles are small enough, they move with the turbulent air in the cloud. On the other hand, as particles become larger their inertia affects their motions, and they move differently than the air. These inertial dynamics impact cloud evolution and ultimately climate prediction, since clouds govern the Earth's energy balances. However, we lack a simple description of the dynamics. Falkovich et al describe theoretically a new dynamical mechanism called the 'sling effect' by which extreme events in the turbulent air cause idealized inertial cloud particles to break free from the airflow (Falkovich et al 2002 Nature 419 151). The sling effect thereafter causes particle trajectories to cross each other within isolated pockets in the flow, which increases the chance of collisions that forms larger particles. We combined experimental techniques that allow for precise control of a turbulent flow with three-dimensional tracking of multiple particles at unprecedented resolution. In this way, we could observe both the sling effect and crossing trajectories between real particles. We isolated the inertial sling dynamics from those caused by turbulent advection by conditionally averaging the data. We found the dynamics to be universal in terms of a local Stokes number that quantifies the local particle velocity gradients. We measured the probability density of this quantity, which shows that sharp

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“…trajectories [9]. While the latter behavior is a matter of common experience, the interpenetration of trajectories has until now not been seen, except in a two-dimensional flow [10].…”

Section: Introductionmentioning

confidence: 99%