BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Dynamics of thin liquid sheets: Theory and Experiments - Mahesh Ti
 rumkudulu (IIT Bombay\, INDIA)
DTSTART:20170608T103000Z
DTEND:20170608T113000Z
UID:TALK72632@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:We study the dynamics of a radial liquid sheet produced by hea
 d-on impingement of two equal laminar liquid jets\, which find application
  in atomization processes ranging from spray painting to combustion.  Whi
 le previous work has focused on the interaction between the surrounding ga
 s phase with the liquid sheet to understanding the sheet dynamics\, our wo
 rk focuses on the importance of sheet thickness variations on the overall 
 dynamics. To this end\, we derive linear stability equations from the invi
 scid flow equations for a radially expanding sheet that govern the time-de
 pendent evolution of the two liquid interfaces. The analysis accounts for 
 the varying liquid sheet thickness while the inertial effects due to the s
 urrounding gas phase are ignored. The analysis results in stability equati
 ons for the sinuous and the varicose modes of sheet deformation that are d
 ecoupled at the lowest order of approximation. When the sheet is excited a
 t a fixed frequency\, a small sinuous displacement introduced at the point
  of impingement grows as it is convected downstream suggesting that the di
 sturbance grows at all Weber numbers ($We=\\rho_l U^2 h/\\sigma$) in the 
 absence of the gas phase. Here\, $\\rho_l$ is the density of the liquid\
 , $U$ is the speed of the liquid jet\, $h$ is the local sheet thickness\
 , and $\\sigma$ is the surface tension. The predictions are compared with
  measurements\, where we use a simple non-contact optical technique based
  on the laser induced fluorescence to measure the instantaneous local shee
 t thickness and its displacement over a range of forcing frequencies and $
 We$. When the impingement point is forced sinusoidally\, sinuous waves pro
 duced close to the impingement point travel radially outward. The measure
 d growth rate of the sinuous wave envelope and the phase speed match the p
 redictions of our theory suggesting that for the range of $We$ considered 
 in the study\, the mechanism for the growth of sinuous waves in liquid she
 ets is primarily due to the thinning of the liquid sheet (and not due to a
 ir interactions). 
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
END:VEVENT
END:VCALENDAR