BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Flow of an aqueous foam through a two-dimensional porous medium: s
 tructure-dynamics couplings - Dollet\, B (CNRS)
DTSTART:20140224T141500Z
DTEND:20140224T143500Z
UID:TALK51046@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Co-authors: Sin A. Jones (Universit Paris 11)\, Baudouin Graud
  (Universit Rennes 1)\, Simon J. Cox (Aberystwyth University)\, Yves Mheus
 t (Universit Rennes 1)\, Isabelle Cantat (Universit Rennes 1) \n\nFlowing 
 foams are used in many engineering and technical applications. They have p
 eculiar flow properties that might be beneficial in applications involving
  porous media. In particular\, viscous dissipation arises mostly from the 
 contact zones between the soap films and the walls\, which results in pecu
 liar friction laws allowing the foam to invade narrow pores more efficient
 ly than Newtonian fluids would. We investigate experimentally the flow of 
 a two-dimensional foam in three geometrical configurations. We first consi
 der a medium consisting of two parallel channels with different widths. Th
 e flow behavior is highly dependent on the foam structure within the narro
 west of the two channels [Jones et al.\, Phys. Fluids 25\, 063101 (2013)]\
 ; consequently\, the flux ratio between the two channels exhibits a non-mo
 notonic dependence on the ratio of their widths. We then consider two para
 llel channels that are respectively convergent and divergent. The resultin
 g flow kinematics imposes asymmetric bubble deformations in the two channe
 ls\; these deformations strongly impact the foam/wall friction\, and conse
 quently the flux distribution between the two channels. We quantitatively 
 predict the flux ratio as a function of the channel widths by modeling pre
 ssure drops of both viscous and capillary origins. This study reveals the 
 crucial importance of boundary-induced bubble deformation on th e mobility
  of a flowing foam. We then study the flow of a foam in a two-dimensional 
 porous medium consisting of randomly-positioned cylindrical grains. Irreve
 rsibility\, intermittency and non-stationarity characterize the velocity f
 ield under permanently imposed inlet flow. In this grain geometry\, flow c
 hanneling appears to be different from what would be expected for a Newton
 ian fluid\, which allows a different part of the pore population to be vis
 ited. The influence of the ratio of the typical pore size to the bubble si
 ze is also addressed.\n
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR