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SUMMARY:Particle entrainment into avalanches: Driven by pore pressures? - 
 Barbara Turnbull\, University of Nottingham
DTSTART:20140509T150000Z
DTEND:20140509T160000Z
UID:TALK52223@talks.cam.ac.uk
CONTACT:Dr C. P.  Caulfield
DESCRIPTION:There is compelling field\, laboratory and DNS evidence of lar
 ge vortex structures within the heads of snow avalanches. In this work we 
 propose that the pore pressures these structures induce within the snow pa
 ck are sufficient to fluidize the pack and feed the avalanche\, contrastin
 g with a traditional approach that assumes particle entrainment is a resul
 t of bed shear stresses. We model the powder snow avalanche as a potential
  flow consisting of a dense source of material thrust into a uniform airfl
 ow. The resulting flow field yields pressure gradients that lead to furthe
 r snow entrainment allowing the powder avalanche to sustain itself. Stabil
 ity analysis of a mass balance involving snow cover and powder cloud yield
 s relations for scouring depth\, frontal height\, speed\, density\, and im
 pact pressure when the frontal region achieves a stable growth rate.
LOCATION:MR2\, Centre for Mathematical Sciences\, Wilberforce Road\, Cambr
 idge
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