Surface waves enhance particle dispersion
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fluids-04-00055.pdf
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1.29 MB
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9804bd6f0b324ae78df80a9298bde3ee
Author(s)
Farazmand, Mohammad M
Sapsis, Themistoklis Panagiotis
Date Issued
March 19, 2019
Journal
Fluids
Publisher
Multidisciplinary Digital Publishing Institute
Citation
Farazmand, Mohammad, and Themistoklis Sapsis, "Surface waves enhance particle dispersion." Fluids 4, 1 (Mar. 2019): no. 55 doi 10.3390/fluids4010055 ©2019 Author(s)
Version
Final published version
Abstract
We study the horizontal dispersion of passive tracer particles on the free surface of gravity waves in deep water. For random linear waves with the JONSWAP spectrum, the Lagrangian particle trajectories are computed using an exact nonlinear model known as the John–Sclavounos equation. We show that the single-particle dispersion exhibits an unusual super-diffusive behavior. In particular, for large times t, the variance of the tracer h|X(t)|² i increases as a quadratic function of time, i.e., h|X(t)|² i ∼ t² . This dispersion is markedly faster than Taylor’s single-particle dispersion theory which predicts that the variance of passive tracers grows linearly with time for large t. Our results imply that the wave motion significantly enhances the dispersion of fluid particles. We show that this super-diffusive behavior is a result of the long-term correlation of the Lagrangian velocities of fluid parcels on the free surface. Keywords: turbulent dispersion; waves; stokes drift
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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Creative Commons Attribution
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DOI of Published Version
https://doi.org/10.3390/fluids4010055
