Dispersion and mixing in quasi-two-dimensional rotating flows

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Abstract

A new rotating-tank experiment has been set up to investigate several aspects of dispersion in forced quasi-two-dimensional turbulence. By superimposing a harmonically varying perturbation on the mean rotation rate the mean flow continually interacts with the no-slip boundaries and forms boundary layers with high-amplitude vorticity twice during the forcing period. By choosing the proper amplitude and frequency of the perturbation it is possible to continuously inject small-scale vorticity in the interior of the flow, either in the form of filamentary structures (detached boundary layers) or as small vortices (after the roll-up of detached boundary layers). We present measurements of the passive scalar spectrum which show good agreement with the k -1 spectrum predicted by Batchelor (J. Fluid Mech. 5:113, 1959). Using particle image velocimetry we are able to reconstruct the Lagrangian trajectories of particles. The relative dispersion rates of particle pairs show an initial exponential separation followed by the classical Richardson dispersion, R 2 ¿ t3.0± 0.1. The variance of the absolute particle displacement grows as s ¿ t1.4, similar to the observations in the previous experiments by Solomon et al. (Phys. Rev. Lett. 71:3975, 1993) and Hansen et al. (Phys. Rev. E 58:7261, 1998). Finally, and indicating future directions of research, we present results of a simple chemical reaction in forced quasi-2D turbulence and show how the bulk reaction rate is controlled by the mixing and filamentation processes.
Original languageEnglish
Title of host publicationTransport and mixing in geophysical flows
EditorsJ.B. Weiss, A. Provenzale
Place of PublicationBerlin
PublisherSpringer
Pages119-136
ISBN (Print)978-3-540-75214-1
DOIs
Publication statusPublished - 2008
Eventconference; Summer Course on Transport in Geophysical Flows ; (Valle d'Aosta, Italy) : 2004.06.14-24; 2004-06-14; 2004-06-24 -
Duration: 14 Jun 200424 Jun 2004

Publication series

NameLecture Notes in Physics
Volume744
ISSN (Print)0075-8450

Conference

Conferenceconference; Summer Course on Transport in Geophysical Flows ; (Valle d'Aosta, Italy) : 2004.06.14-24; 2004-06-14; 2004-06-24
Period14/06/0424/06/04
OtherSummer Course on Transport in Geophysical Flows ; (Valle d'Aosta, Italy) : 2004.06.14-24

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    Wells, M. G., Clercx, H. J. H., & Heijst, van, G. J. F. (2008). Dispersion and mixing in quasi-two-dimensional rotating flows. In J. B. Weiss, & A. Provenzale (Eds.), Transport and mixing in geophysical flows (pp. 119-136). (Lecture Notes in Physics; Vol. 744). Springer. https://doi.org/10.1007/978-3-540-75215-8_6