BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:Suspensions of particles and bubbles in yield stress fluids
DTSTART:20160429T121500
DTEND:20160429T131500
DTSTAMP:20260922T013847Z
UID:e65ebd8c6852178a4f9052b4b617dfa722b5bfb606ac8218b26d3be2
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Guillaume Ovarlez\, Senior Research Scientist at LOF-CNRS-S
 olvay-University of Bordeaux\, France\nMany dense suspensions involved in 
 industrial processes (concrete casting\, drilling muds\, foodstuff transpo
 rt\, etc.) and natural phenomena (debris-flows\, lava flows\, etc.) are yi
 eld stress fluids which contain a significant fraction of coarse rigid par
 ticles. In addition\, some of these materials contain air bubbles: crystal
  bearing magmas\, aerated food emulsions\, foamed plaster slurries… When
  scale separation between the paste microstructure (the colloidal particle
  size) and the noncolloidal particles or bubbles in suspension is possible
 \, a simplification occurs: these materials can be considered as noncolloi
 dal particles or bubbles embedded in a yield stress fluid (the colloidal p
 aste). From a fundamental point of view\, one then deals with suspensions 
 in which particles interact through nonlinear hydrodynamical interactions.
 \nIn this talk\, we will present recent advances in the characterization a
 nd understanding of the behavior of suspensions of rigid and soft inclusio
 ns in yield stress fluids.\nWe will first show how model materials and app
 ropriate procedures are designed to focus on the purely mechanical contrib
 ution of the particles/bubbles to the yield stress fluid behavior\, indepe
 ndently of the physicochemical properties of the materials. This allows an
  in depth comparison with micromechanical estimates. We will then focus on
  the impact of particles on the linear and nonlinear rheological propertie
 s (elastic modulus\, yield stress\, consistency) of the fluid. The variati
 ons of these properties with the particle volume fraction are found to be 
 in good agreement with those predicted by a micromechanical approach in wh
 ich the concentration of shear between the inclusions is taken into accoun
 t. In the case of suspensions of bubbles\, bubbles can behave as rigid or 
 soft particles\, dependant on their physical properties and on the interst
 itial fluid mechanical properties\; we will show that the visco-elastic an
 d visco-plastic behaviors of these materials are governed by two different
  dimensionless capillary numbers\, which gives rise to original properties
 .\nWe will finally briefly discuss shear-induced migration and shear-induc
 ed sedimentation issues. These phenomena can be quantitatively modeled whe
 n the 3D behavior of the interstitial yield stress fluid and the local pro
 perties of shear between the particles are taken into account.\nReferences
 :\n1. F. Mahaut\, X. Chateau\, P. Coussot\, G. Ovarlez\, Yield stress and 
 elastic modulus of suspensions of noncolloidal particles in yield stress f
 luids\, Journal of Rheology 52\, 287-313 (2008).\n2. X. Chateau\, G Ovarle
 z\, K. Luu Trung\, Homogenization approach to the behavior of suspensions 
 of noncolloidal particles in yield stress fluids\, Journal of Rheology 52\
 , 489-506 (2008).\n3. T.-S. Vu\, G. Ovarlez\, X. Chateau\, Macroscopic beh
 avior of bidisperse suspensions of noncolloidal particles in yield stress 
 fluids\, Journal of Rheology 54\, 815-833 (2010).\n4. G. Ovarlez\, F. Bert
 rand\, P. Coussot\, X. Chateau\, Shear-induced sedimentation in yield stre
 ss fluids\, Journal of Non-Newtonian Fluid Mechanics 42\, 148-157 (2012).\
 n5. L. Ducloué\, O. Pitois\, J. Goyon\, X. Chateau\, G. Ovarlez\, Couplin
 g of elasticity to capillarity in soft aerated materials\, Soft Matter 10\
 , 5093-5098 (2014).\n6. L. Ducloué\, O. Pitois\, J. Goyon\, X. Chateau\, 
 G. Ovarlez\, Rheological behaviour of suspensions of bubbles in yield stre
 ss fluids\, Journal of Non-Newtonian Fluid Mechanics 215\, 31-39 (2015).\n
 7. G. Ovarlez\, F. Mahaut\, S. Deboeuf\, N. Lenoir\, S. Hormozi\, X. Chate
 au\, Flows of suspensions of particles in yield stress fluids\, Journal of
  Rheology (2015).\nBio :\nDr Guillaume Ovarlez is senior research scientis
 t (Directeur de Recherche) at CNRS Laboratory Of the Future in Bordeaux\, 
 France since 2014. He previously was a CNRS senior researcher at Laboratoi
 re Navier\, Ecole des Ponts since 2003. He holds a PhD in Physics from Uni
 versity Paris XI and an engineering degree from Ecole Polytechnique\, Fran
 ce. Dr Ovarlez has notably received the Bronze Medal of CNRS in 2009\, and
  the prix “de la Recherche” in 2007 for his work on rheology of comple
 x suspensions.
LOCATION:GCB330 http://plan.epfl.ch/?lang=fr&room=GCB330
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR