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SUMMARY:A Maxwell-Elasto-Brittle model for the drift and deformation of se
 a ice - Veronique Dansereau (CNRS (Centre national de la recherche scienti
 fique))
DTSTART:20171208T090000Z
DTEND:20171208T100000Z
UID:TALK96364@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:In recent years\, the viscous hypothesis and other underlying 
 physical assumptions of the viscous-plastic (VP) rheology widely used in c
 urrent climate and operational models have been revisited and found to be 
 inconsistent with the observed mechanical behaviour of sea ice. Other stud
 ies have suggested that while the VP model can represent the mean global d
 rift of sea ice with a certain level of accuracy\, it fails at reproducing
  some key observed properties of sea ice deformation. We developed a new m
 echanical model\, named Maxwell-Elasto-Brittle\, as an alternative to the 
 VP rheology in the view of accurately reproducing the drift and deformatio
 n of the ice cover in continuum sea ice models. The model builds on a dama
 ge mechanics framework used for ice and rocks. A viscous-like relaxation t
 erm is added to a linear-elastic constitutive relationship together with a
 n effective viscosity that evolves with the local level of damage of the m
 aterial\, like its elastic modulus. This framework allows the internal str
 ess to dissipate in large\, permanent deformations along faults\, or leads
 \, once the material is highly damaged\, while reproducing the small defor
 mations associated with the fracturing process and retaining the memory of
  elastic deformations over relatively low damage areas. A healing mechanis
 m counterbalances the effects of damaging over large time scales.  <br><sp
 an><br>Idealized simulations have confirmed that the Maxwell-EB model repr
 oduces the important characteristics of sea ice mechanics revealed by the 
 analyses of available ice buoy and satellite data: the anisotropy of the d
 eformation\, the strain localization and intermittency\, as well as the as
 sociated scaling laws. Sensitivity analyses show that the model\, with few
  independent variables\, can represent a large range of mechanical behavio
 urs\, with both the persistence of creeping leads and the activation of ne
 w leads with different shapes and orientations. Realistic simulations will
  be presented\, in particular\, simulations of the flow of ice through Nar
 es Strait. These will demonstrate that the model reproduces the formation 
 of stable ice bridges as well as the stoppage of the flow\, a common pheno
 menon within numerous channels of the Arctic. In agreement with observatio
 ns\, the propagation of damage along narrow arch-like kinematic features\,
  the discontinuities in the velocity field across these features\, definin
 g floes\, and the eventual opening of polynyas downstream of the Strait ar
 e all represented.</span>
LOCATION:Seminar Room 1\, Newton Institute
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