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SUMMARY:EESS talk on "Physics and modeling of wind-blown sand and snow"
DTSTART:20160927T121500
DTEND:20160927T131500
DTSTAMP:20260928T184149Z
UID:64f73e635f9b76958fb54bf3a1436e836856ecce36a6608689602440
CATEGORIES:Conferences - Seminars
DESCRIPTION:Mr Francesco Comola\, CRYOS\nAbstract: The aeolian transport o
 f granular materials\, such as sand and snow\, is responsible for a wide r
 ange of environmental effects. Drifting sand forms dunes and ripples\, ero
 des geological features\, generates dust emission and provides a limited a
 mount of nutrients to several ecosystems. Drifting snow\, on the other han
 d\, controls mass and energy budgets of polar and alpine regions\, with re
 levant impacts on sea level rise\, avalanche triggering\, and water resour
 ces management. Here\, we provide a better insight into the physics of sed
 iment transport by investigating two fundamental surface processes\, namel
 y particle ejection and particle fragmentation. Impact-ejection dynamics\,
  the so-called splash entrainment\, is modeled through a stochastic ejecti
 on function derived from energy and momentum conservation laws. Our analys
 is suggests the ejection regime of saltating snow is strongly controlled b
 y cohesion and that the anti-correlation between mass and velocity of ejec
 ted grains significantly increases the average number of ejecta. We review
  recent advances in the field of dust aggregate fragmentation and propose 
 a new fragmentation theory for fractal snow crystals during wind-driven sa
 ltation. Our theoretical framework successfully explains the typical featu
 res of blowing-snow size distributions\, i.e. the emergence of a self-simi
 lar scaling for large diameters and the deviation from the power-law distr
 ibution for small diameters. Finally\, we account for the improved underst
 anding of surface processes in a sediment transport model based on Large E
 ddy Simulations and Lagrangian-stochastic particle tracking. An Immersed B
 oundary Method is also adopted to effectively reproduce the surface drag e
 xerted by complex terrains. The comprehensive modeling approach proves a s
 olid base for studies of aeolian transport in arid and polar regions\, as 
 well as on other planets.\n\nShort biography: Francesco Comola received hi
 s B.Sc. and M.Sc. degrees in Civil Engineering at University of Padova\, I
 taly. His master project in hydraulics was carried out at Aalborg Universi
 ty\, Denmark\, with the support of an Erasmus scholarship. He is currently
  Ph.D. student in the CRYOS Lab. at EPFL. His research focuses on transpor
 t phenomena in snow-covered environments.  He seeks to cast complex trans
 port processes in statistical-mechanics frameworks\, which he employed to 
 model temperature dynamics in alpine streams and wind-driven transport of 
 snow in polar regions. He was recently granted the EDCE mobility scholarsh
 ip to conduct research on fragmentation of wind-blown snow crystals at the
  University of California\, Los Angeles.
LOCATION:GR A3 31 http://plan.epfl.ch/?room=GR%20A3%2031
STATUS:CONFIRMED
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