Lagrangian description of the unsteady flow induced by a single pulse of a jellyfish

Research output: Contribution to journalArticle

Abstract

Lagrangian statistics and pair dispersion induced by an isolated pulse of a small jellyfish, Aurelia aurita, were quantified and characterized using 3D particle tracking velocimetry (3D-PTV). Probability density functions (PDF) of the Lagrangian velocity components indicated more intense mixing in the radial direction and revealed three stages dominated by flow acceleration, mixing, and dissipation. Time evolution of the Lagrangian acceleration variance further illustrates each phase. During the mixing phase, the flow shares characteristics of homogeneous isotropic turbulence. In addition, we show that a single pulse may induce rich wake dynamics characterized by pair dispersion with a super-diffusive t3 regime due to large-scale flow inhomogeneity, followed by a coherent t2-Batchelor scaling and then t1-Brownian motions. The first trend occurred in the accelerated flow, whereas the second dynamic was observed in the mixed wake and depended on the initial separation. The Brownian motion was present in the late stage dominated by flow dissipation. Kolmogorov microscales during the fully mixed phase were obtained with three distinct approaches, namely, Heisenberg-Yaglom relation of the Lagrangian acceleration variance, the fluctuating rate of the strain tensor in the Eulerian frame of reference as well as the Batchelor scaling in pair dispersion, which showed good agreement.

Original languageEnglish (US)
Article number064605
JournalPhysical Review Fluids
Volume4
Issue number6
DOIs
StatePublished - Jun 6 2019

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Unsteady Flow
Unsteady flow
Brownian movement
Wake
Brownian motion
Dissipation
Velocity measurement
Probability density function
Tensors
Scaling
Turbulence
Particle Tracking
Statistics
Inhomogeneity
Tensor
Distinct

ASJC Scopus subject areas

  • Computational Mechanics
  • Modeling and Simulation
  • Fluid Flow and Transfer Processes

Cite this

Lagrangian description of the unsteady flow induced by a single pulse of a jellyfish. / Kim, Jin Tae; Chamorro Chavez, Leonardo Patricio.

In: Physical Review Fluids, Vol. 4, No. 6, 064605, 06.06.2019.

Research output: Contribution to journalArticle

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