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  • Letter
  • Open Access

Paths to caustic formation in turbulent aerosols

Jan Meibohm1, Vikash Pandey2, Akshay Bhatnagar3, Kristian Gustavsson1, Dhrubaditya Mitra3, Prasad Perlekar2, and Bernhard Mehlig1

  • 1Department of Physics, Gothenburg University, SE-41296 Gothenburg, Sweden
  • 2TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Gopanpally, Hyderabad 500046, India
  • 3NORDITA, Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden

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Phys. Rev. Fluids 6, L062302 – Published 9 June, 2021

DOI: https://doi.org/10.1103/PhysRevFluids.6.L062302

Abstract

The dynamics of small, yet heavy, identical particles in turbulence exhibits singularities, called caustics, that lead to large fluctuations in the spatial particle-number density, and in collision velocities. For large particle inertia, the fluid velocity at the particle position is essentially a white-noise signal and caustic formation is analogous to Kramers escape. Here we show that caustic formation at small particle inertia is different. Caustics tend to form in the vicinity of particle trajectories that experience a specific history of fluid-velocity gradients, characterized by low vorticity and a violent strain exceeding a large threshold. We develop a theory that explains our findings in terms of an optimal path to caustic formation that is approached in the small inertia limit.

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Phys. Rev. Fluids 6, L062302– Published 9 June, 2021
  • Received 26 November 2020
  • Accepted 11 May 2021
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by Bibsam.

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