Turbulent particle pair diffusion: Numerical simulations

PLoS One. 2019 May 20;14(5):e0216207. doi: 10.1371/journal.pone.0216207. eCollection 2019.

Abstract

A theory for turbulent particle pair diffusion in the inertial subrange [Malik NA, PLoS ONE 13(10):e0202940 (2018)] is investigated numerically using a Lagrangian diffusion model, Kinematic Simulations [Kraichnan RH, Phys. Fluids 13:22 (1970); Malik NA, PLoS ONE 12(12):e0189917 (2017)]. All predictions of the theory are observed in flow fields with generalised energy spectra of the type, E(k) ∼ k-p. Most importantly, two non-Richardson regimes are observed: for short inertial subrange of size 102 the simulations yield quasi-local regimes for the pair diffusion coefficient, [Formula: see text]; and for asymptotically infinite inertial subrange the simulations yield non-local regimes [Formula: see text], with γ intermediate between the purely local scaling γl = (1 + p)/2 and the purely non-local scaling γnl = 2. For intermittent turbulence spectra, E(k) ∼ k-1.72, the simulations yield [Formula: see text], in agreement with the revised 1926 dataset [Formula: see text] [Richardson LF, Proc. Roy. Soc. Lond. A 100:709 (1926); Malik NA, PLoS ONE 13(10):e0202940 (2018)]. These results lend support to the physical picture proposed in the new theory that turbulent diffusion in the inertial subrange is governed by both local and non-local diffusion transport processes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomechanical Phenomena / physiology*
  • Computer Simulation
  • Diffusion
  • Motion
  • Physical Phenomena

Grants and funding

NAM received funding from SABIC (Saudi Arabian Basic Industries Corporation) through grant number SB101011. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.