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The relaxation time for viscous and porous gravity currents following a change in flux

dc.creatorBall, Thomasina
dc.creatorHuppert, Herbert Eric
dc.creatorLister, John Ronald
dc.creatorNeufeld, Jerome Anthony
dc.date.accessioned2017-03-27
dc.date.accessioned2018-11-24T23:20:13Z
dc.date.available2017-07-05T11:46:59Z
dc.date.available2018-11-24T23:20:13Z
dc.date.issued2017-06-01
dc.identifierhttps://www.repository.cam.ac.uk/handle/1810/265188
dc.identifier.urihttp://repository.aust.edu.ng/xmlui/handle/123456789/3568
dc.description.abstractThe equilibration time in response to a change in flux from Q to $\Lambda$Q after an injection period applied to either a low-Reynolds-number gravity current or one propagating through a porous medium, in both axisymmetric and one-dimensional geometries, is shown to be of the form $\tau$ = Tf($\Lambda$) , independent of all the remaining physical parameters. Numerical solutions are used to investigate f($\Lambda$) for each of these situations and compare very well with experimental results in the case of an axisymmetric current propagating over a rigid horizontal boundary. Analysis of the relaxation towards self-similarity provides an illuminating connection between the excess (deficit) volume from early times and an asymptotically equivalent shift in time origin, and hence a good quantitative estimate of $\tau$ . The case of $\Lambda$ = 0 equilibration after ceasing injection at time T is a singular limit. Extensions to high-Reynolds-number currents and to the case of a constant-volume release followed by constant-flux injection are discussed briefly.
dc.languageen
dc.publisherCambridge University Press
dc.publisherJournal of Fluid Mechanics
dc.titleThe relaxation time for viscous and porous gravity currents following a change in flux
dc.typeArticle


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