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Accueil du site > Recherche > Projets > Thème Fluides & Matériaux Complexes > Liquid foams

Liquid foams

- Leader : Raufaste Christophe

- Collaborators within the LPMC : Fraysse Nathalie, Rajchenbach Jean, Bouret Yann

- External Collaborators : Mader Kevin and Mokso Rajmund (Paul Scherrer Institute, Suisse), Dollet Benjamin (Institut de Physique de Rennes, Rennes), Santucci Stéphane (Laboratoire de Physique de l’ENS Lyon), Argentina Médéric (INLN, Université Nice Sophia Antipolis)

- PhD/Post-doctoral fellows : Cohen Alexandre

- Description :

Liquid foams exhibit interesting mechanical properties exploited by food, cosmetic or oil industries. They are easy to produce ; their structure is mainly made of gas bubbles dispersed inside a continuous liquid phase and stabilized by surfactants. This multiphasic feature leads to a two-fold rheological behavior : liquid foams behave as solids when submitted to small stresses and flow like liquids above a yield stress. While classical rheometry aims at characterizing the macroscopic behavior of materials such as foams, our goal is to link the macroscopic scale with the local mechanisms that are in interplay at the bubble scale : deformation, rearrangement, liquid flow and dissipation. The "Liquid Foams" project developed at our institute is divided into three parts and tackled with several methods.

  • Dynamics of a Plateau border : Inside a liquid foam, the contacts between three bubbles form liquid channels called Plateau borders. These latter are important constituents since they contain most of the foam liquid. The originality of the setup consists in creating a single Plateau borders inside an elementary foam cell and in studying how this object responds to external mechanical stimuli (e.g. harmonic excitation, capillary suction).
  • Acoustics of liquid foams : The use of sound waves is an in situ and non destructive method to probe the mechanical properties of materials. We couple acoustics measurements (speed, dispersion, damping) with direct imaging of the structure (films, bubbles) to understand the mechanisms of deformation and relaxation at the bubble scale.
  • Imaging and Rheology of 3D foams : Foams are difficult to image since they are opaque beyond a few layers of bubbles. For that reason, we probe "in depth" 3D foams by use of the X-ray tomography facility developed at the Swiss Light Source (Villingen, Switzerland). From images of foam flows, we got information at the bubble scale (displacements, deformations, rearrangements).

Mots-clés

Fluides & Matériaux Complexes, Fluides Complexes, MIMIC