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SUMMARY:Richard Mott &amp\; Seung Yeon Lee: BPI Research Colloquium - Rich
 ard Mott &amp\; Seung Yeon Lee
DTSTART:20101202T113000Z
DTEND:20101202T123000Z
UID:TALK28270@talks.cam.ac.uk
CONTACT:Helen Mawdsley
DESCRIPTION:Richard Mott\n\nNatural ventilation of an enclosed space drive
 n by periodic gusting of wind\n \nWe investigate the mixing of a warm encl
 osed space by a series of discrete gusts of cold air from a high level ope
 ning. Initially we examine the case of a series of gusts of identical size
  each modelled as a turbulent buoyant thermal and develop a model of the f
 illing box like flow which develops in the space.  We successfully test th
 e predictions of the model with a series of new laboratory experiments. Th
 e experiments combined with the model also provide a new independent estim
 ate for the entrainment coefficient of a thermal\, based on the propagatio
 n speed of a filling box front. We then examine the mixing produced by a s
 eries of thermals of non identical size which we characterise in terms of 
 a mean size and coefficient of variation. We find that as the coefficient 
 of variation increases\, the density profile becomes progressively more st
 ratified owing to the asymmetry of dilution through entrainment of large a
 nd small thermals. \n\nSeung Yeon Lee\n\nInterfacial Studies on a Charged 
 Surface in Oil by Contact Angle Measurements\n\nContact angles are depende
 nt upon three interfacial energies: γsolid/liquid\, γsolid/vapour\, and 
 γliquid/vapour according to Young’s relation. Solid\, liquid and vapour
  phases in this work are respectively amorphous silicates\, water droplets
  and oil media. Due to the three variables\, contact angles could be insuf
 ficient but necessary to study the surface modification and water adsorpti
 on on the surfaces in situ. Surfactants\, Ca(AOT)2 added in the oil phase 
 can modify the surface via a cation bridging and hence the surface tension
 \, γsolid/liquid. Added electrolytes in water droplets can vary the water
  adsorption on the modified surfaces.
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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