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Patterns of solidification in channel flows with surface cooling

Griffiths, Ross; Kerr, Ross; Cashman, Katharine

Description

Understanding the rates of cooling and solidification in laminar flows down sloping channels is central to predicting the advance of lava flows. The mechanisms involved include thermal convection and a competition between shear strain rate and the rate of formation of solid at the chilled surface of the flow. We report experiments in which polyethylene glycol wax flows in a laminar fashion down an inclined, open channel of rectangular cross-section under cold water. Two distinctly different...[Show more]

dc.contributor.authorGriffiths, Ross
dc.contributor.authorKerr, Ross
dc.contributor.authorCashman, Katharine
dc.date.accessioned2015-12-13T22:36:40Z
dc.date.available2015-12-13T22:36:40Z
dc.identifier.issn0022-1120
dc.identifier.urihttp://hdl.handle.net/1885/76878
dc.description.abstractUnderstanding the rates of cooling and solidification in laminar flows down sloping channels is central to predicting the advance of lava flows. The mechanisms involved include thermal convection and a competition between shear strain rate and the rate of formation of solid at the chilled surface of the flow. We report experiments in which polyethylene glycol wax flows in a laminar fashion down an inclined, open channel of rectangular cross-section under cold water. Two distinctly different flow regimes are recognized: 'tube' flow in which solidification of the flow surface creates a stationary roof while melt continues to flow through a relatively well-insulated 'tube' beneath, and a 'mobile crust' regime in which a solid surface crust develops only in the centre of the channel. In the latter regime the crust is carried down the channel, separated from the walls by crust-free shear regions in which cooling produces only dispersed fragments of solid owing to the effects of shearing. This flow structure is quasi-invariant over a large distance downstream. We show that thermal convection takes place in organized rolls that have axes aligned with the shear flow, and conclude that transition between the two flow regimes occurs at a critical value of the combined parameter ν = Ψ(Ra/R0)1/3, where Ψ = U0ts/Ho is the ratio of a surface solidification timescale ts to a shearing timescale H0/U0, H0 and U0 are the flow depth and centreline surface velocity in the absence of solidification, Ra is a Rayleigh number and R0 is a constant.
dc.publisherCambridge University Press
dc.sourceJournal of Fluid Mechanics
dc.subjectKeywords: Channel flow; Heat convection; Laminar flow; Shear flow; Solidification; Flow structures; Surface cooling; Fluid mechanics; fluid mechanics; solidification
dc.titlePatterns of solidification in channel flows with surface cooling
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume496
dc.date.issued2003
local.identifier.absfor040403 - Geophysical Fluid Dynamics
local.identifier.absfor040314 - Volcanology
local.identifier.ariespublicationMigratedxPub5677
local.type.statusPublished Version
local.contributor.affiliationGriffiths, Ross, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationKerr, Ross, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationCashman, Katharine, University of Oregon
local.bibliographicCitation.startpage33
local.bibliographicCitation.lastpage62
local.identifier.doi10.1017/S0022112003006517
dc.date.updated2015-12-11T09:32:50Z
local.identifier.scopusID2-s2.0-1142281930
CollectionsANU Research Publications

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