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SUMMARY:Turbulent miscible fountains - height\, rhythm and scales. - Dr He
 nry Burridge\, CUED 
DTSTART:20130531T120000Z
DTEND:20130531T131500Z
UID:TALK44744@talks.cam.ac.uk
CONTACT:ROBERTA TRUPIANO
DESCRIPTION:Miscible turbulent fountains dilute the concentration of any c
 ontaminants present in the vertical release of fluid\, including for examp
 le the buoyancy scalar (temperature or solute concentration). This process
  occurs through the action of turbulent entrainment and is similarly prese
 nt in positively buoyant plumes. Unlike plumes\, however\, fountains descr
 ibe a vertical release of fluid such that the density difference\, between
  the source fluid and the environment\, gives rise to a buoyancy force whi
 ch opposes the source momentum. As such\, fountains travel vertically with
 in the environment before the buoyancy acts to reverse the flow\, which th
 en turns back towards the source. In this way\, fountains dilute the prope
 rties of the source fluid over a limited\, and known\, vertical extent\; t
 hereby offering the potential to assist in any situation where localised m
 ixing is required. Fountain-induced mixing has previously been applied in 
 low-energy ventilation schemes but\, with better understanding\, offers sc
 ope to contribute in a number of applications.\n\nResults will be presente
 d from an experimental study in which fountains were generated by ejecting
  dense saline solution vertically upwards into a freshwater environment. A
 n investigation into fountain rise height proposes a new classification of
  fountains. Analysis of the turbulent fluctuations in fountain height iden
 tifies dominant a time scale within each fountain class\, these time scale
 s are consistent with the dominant length (height) scales and physically a
 pparent velocity scales. On dimensional grounds\, we develop expressions f
 or the fluxes of volume\, momentum and buoyancy within the fountain outflo
 w (the reverse-flow in the plane of the source) and show these fluxes atta
 in a constant ratio which is invariant with the fountain's source conditio
 ns.
LOCATION:LR10\, Baker Building (South wing).
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