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dc.contributor.authorIssler, Dieter
dc.date.accessioned2017-11-07T10:59:32Z
dc.date.available2017-11-07T10:59:32Z
dc.date.created2014-10-30T07:22:41Z
dc.date.issued2014
dc.identifier.citationJournal of Fluid Mechanics. 2014, 759 701-738.nb_NO
dc.identifier.issn0022-1120
dc.identifier.urihttp://hdl.handle.net/11250/2464577
dc.description.abstractThe bed entrainment rate in a gravity mass flow (GMF) is uniquely determined by the properties of the bed and the flow. In depth-averaging, however, critical information on the flow variables near the bed is lost and empirical assumptions usually are made instead. We study the interplay between bed and flow assuming a perfectly brittle bed, characterized by its shear strength , and erosion along the bottom surface of the flow; frontal entrainment is neglected here. The brittleness assumption implies that the shear stress at the bed surface cannot exceed . For quasi-stationary flows in a simplified setting, analytic solutions are found for Bingham and frictional–collisional (FC) fluids. Extending this theory to non-stationary flows requires some assumptions for the velocity profile. For the Bingham fluid, the profile of a ‘proxy’ quasi-stationary eroding flow is used; the rheological parameters are chosen to match the instantaneous velocity and shear-layer depth of the non-stationary flow. For the FC fluid, a two-parameter family of functions that closely match the profiles obtained in depth-resolved numerical simulations is assumed; the boundary conditions determine the instantaneous parameter values and allow computation of the erosion rate. Preliminary tests with the FC erosion formula incorporated in a simple slab model indicate that the non-stationary erosion formula matches the depth-resolved simulations asymptotically, but differs in the start-up phase. The non-stationary erosion formulae are valid only up to a limit velocity (and to a limit flow depth if there is Coulomb friction). This appears to mark the transition to another erosion regime – to be described by a different model – where chunks of bed material are intermittently ripped out and gradually entrained into the flow.nb_NO
dc.language.isoengnb_NO
dc.titleDynamically consistent entrainment laws for depth-averaged avalanche modelsnb_NO
dc.typeJournal articlenb_NO
dc.typePeer reviewednb_NO
dc.description.versionsubmittedVersionnb_NO
dc.source.pagenumber701-738nb_NO
dc.source.volume759nb_NO
dc.source.journalJournal of Fluid Mechanicsnb_NO
dc.identifier.doi10.1017/jfm.2014.584
dc.identifier.cristin1168230
dc.subject.keywordAvalanche-RnD
dc.subject.keywordSnøskred-FoU
cristin.unitcode7452,3,1,0
cristin.unitnameSnø- og steinskred
cristin.ispublishedtrue
cristin.fulltextpostprint
cristin.qualitycode2


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