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PRODID:-//Columba Systems Ltd//NONSGML CPNG/SpringViewer/ICal Output/3.3-
 M3//EN
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20190926T092423Z
DTSTART:20191002T130000Z
DTEND:20191002T135000Z
SUMMARY:Yuri Sobral - Collapse of immersed granular columns
UID:{http://www.columbasystems.com/customers/uom/gpp/eventid/}mhi-k0fes8h
 v-w0hb7i
DESCRIPTION:Yuri Dumaresq Sobral (University of Brasilia) joins us for th
 e Physical Applied Mathematics Series. Note the unusual room - 5.210 in 
 University Place.\n\n\nThe collapse of granular columns in a viscous flu
 id is a common model case for submarine geophysical flows. In a column c
 ollapse\, an initial granular column of grains is suddenly put into moti
 on by gravity\, which then spreads and deposits over a certain runout di
 stance. In dry collapses\, the initial aspect ratio of the column is kno
 wn to be the major controlling parameter of the final runout. However\, 
 when the granular column is immersed in a fluid\, this problem is not ye
 t fully understood. This talk addresses two major parameters\, i.e.\, th
 e initial aspect ratio and the initial packing density\, based on two ty
 pes of fluid-particle coupling schemes. In the first part of this talk\,
  results on local-averaged fluid-particle simulations for a wide range o
 f initial aspect ratios will be presented. Both similar and distinct fea
 tures are observed in immersed collapses compared to their dry counterpa
 rts. Underwater collapses for large aspect ratios exhibit unique dynamic
 s as the eddies generated in water erode the surface of the granular lay
 er\, thus modifying the deposit morphology. The influence of the sample 
 size and of the model parameters will also be discussed. In the second p
 art\, an investigation of the influence of packing density based on pore
 -scale direct numerical simulations will be presented. Dense packings re
 sult in slow dynamics and short runout distances\, while loose packings 
 are associated with fast dynamics and long runout distances. The simulat
 ions provide micromechanical evidence of the pore pressure feedback mech
 anism on the triggering and runout stages of the immersed granular colla
 pse. Comparisons with results obtained over a wide range of length scale
 s\, including small-scale numerical and experimental data and large-scal
 e field data\, will be presented.
STATUS:TENTATIVE
TRANSP:TRANSPARENT
CLASS:PUBLIC
LOCATION:5.210\, University Place\, Manchester
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