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SUMMARY:See Below - Patrick Mortimer\, BPI and Eric Newland\, BPI
DTSTART:20201105T113000Z
DTEND:20201105T123000Z
UID:TALK151804@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:Paddy Mortimer - Capillary driven flows in a non-uniform Hele-
 Shaw cell\n\nWe consider flow driven by capillary forces in a channel with
  a non-uniform gap width. We first present similarity solutions for a fini
 te release of fluid in a channel where the cross-sectional profile is desc
 ribed by some power law.  We find that this power law significantly influe
 nces the shape of the current and the rate of migration through the channe
 l. We then we look to relate the well-known confined solution from Romero 
 and Yost (1996) to the unconfined solution from Wieslogel and Lichter (199
 8) by showing the transition time from the former to the latter is a funct
 ion of the aspect ratio of the confined current. Then by including gravity
  effects in the cross-channel direction we show a transition from early ti
 me gravity current to later time capillary current behaviour. We also show
  experimentally\, that an along channel component of gravity can lead to s
 hock solutions with a capillary dominated boundary layer\, migrating throu
 gh the thinnest section of the channel. In the final section we present so
 me calculations in the context of CO2 sequestration\, which show that post
 -injection\,  late time capillary behaviour may lead to an increase the fi
 nal extent of the current and a decrease in the trapping efficiency.\n\nEr
 ic Newland - On Particle Fountains in a Stratified Environment\n\nThere ar
 e a number of situations in which particle laden fluid is released into th
 e environment\, leading to the formation of a particle laden flow. Importa
 nt examples include volcanic eruption columns in both sub-aqueous and sub-
 aerial settings\; turbidity currents which run down the continental shelf 
 and particle plumes formed during deep sea mining. The dynamics of these f
 lows are complex\, involving both the buoyancy of the particle laden suspe
 nsion and also the separation of the particles and the fluid\, especially 
 when the convective flow speeds become comparable to the particle fall spe
 ed. Although the dynamics of particle laden buoyant plumes and gravity cur
 rents have received considerable attention \, there has been less attentio
 n placed on particle laden fountains\, although these are of considerable 
 relevance for the dynamics of volcanic eruption columns in both sub-aerial
  and sub-aqueous environments.\n\nI present a series of experiments explor
 ing the dynamics of particle-laden fountains rising through a stratified e
 nvironment with zero buoyancy flux at the source. We find that the ratio U
  between the particle sedimentation speed Vs and the characteristic founta
 in velocity has a profound effect on the structure of the fountain and the
  dispersal of the particles. We compare the observations with some simple 
 integral models of the fountain flow\, to predict the height of rise of th
 e fountain and of the intrusions which develop as the particles separate f
 rom the flow and the fountain fluid spreads radially from the fountain. We
  also describe the radial extent of the particles as they settle from the 
 flow.
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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