Show simple item record

Efficient mixing in stratified flows: experimental study of a Rayleigh-Taylor unstable interface within an otherwise stable stratification

dc.creatorDavies-Wykes, Megan S
dc.creatorDalziel, Stuart Bruce
dc.date.accessioned2018-11-24T23:17:59Z
dc.date.available2015-03-16T10:05:35Z
dc.date.available2018-11-24T23:17:59Z
dc.date.issued2014-09-09
dc.identifierhttps://www.repository.cam.ac.uk/handle/1810/247008
dc.identifier.urihttp://repository.aust.edu.ng/xmlui/handle/123456789/3205
dc.description.abstractBoussinesq salt-water laboratory experiments of Rayleigh–Taylor instability (RTI) can achieve mixing efficiencies greater than 0.75 when the unstable interface is confined between two stable stratifications. This is much greater than that found when RTI occurs between two homogeneous layers when the mixing efficiency has been found to approach 0.5. Here, the mixing efficiency is defined as the ratio of energy used in mixing compared with the energy available for mixing. If the initial and final states are quiescent then the mixing efficiency can be calculated from experiments by comparison of the corresponding density profiles. Varying the functional form of the confining stratifications has a strong effect on the mixing efficiency. We derive a buoyancy-diffusion model for the rate of growth of the turbulent mixing region, h˙=2αAgh−−−−−√ (where A=A(h) is the Atwood number across the mixing region when it extends a height h, g is acceleration due to gravity and α is a constant). This model shows good agreement with experiments when the value of the constant α is set to 0.07, the value found in experiments of RTI between two homogeneous layers (where the height of the turbulent mixing region increases as h=αAgt2, an expression which is equivalent to that derived for h˙).
dc.languageen
dc.publisherCambridge University Press
dc.publisherJournal of Fluid Mechanics
dc.rightshttp://creativecommons.org/licenses/by-nc/2.0/uk/
dc.rightsAttribution-NonCommercial 2.0 UK: England & Wales
dc.subjectbuoyancy-driven instability
dc.subjectturbulent mixing
dc.subjectmixing efficiency
dc.subjectRayleigh-Taylor instability
dc.titleEfficient mixing in stratified flows: experimental study of a Rayleigh-Taylor unstable interface within an otherwise stable stratification
dc.typeArticle


Files in this item

FilesSizeFormatView
Davies-Wykes 2014 Journal of Fluid Mechanics.pdf12.83Mbapplication/pdfView/Open

This item appears in the following Collection(s)

Show simple item record