- Permanents members: Sylvie Cohen-Addad, Reinhard Höhler
In microgravity, isolated gas bubbles in a liquid are spheres. Dilute dispersions of them behave as liquids. When the volume liquid fraction exceeds a critical value called « jamming transition », the bubbles are compressed against each other and form a foam. In such a dense packing, disordered or not, bubbles are deformed which confers mechanical properties to the foam. It may behave either as a soft solid under a weak load or flow as viscous fluid beyond a yield applied stress. In microgravity, a foam ages with time due to the effect of coalescence provoked by film ruptures or due to the effect of coarsening induced by gas diffusion between neighboring bubbles. These processes generate internal foam dynamics where elementary events are local intermittent bubble rearrangements.
We study the structure and dynamics of coarsening foams in microgravity in the domain of « wet » foams near the jamming transition. This domain is impossible to explore on ground because gravity drains the liquid through the foam much more rapidly than foam coarsen ! Our purpose is to establish the bubble growth laws, the bubble size distributions and the dynamics of rearrangements in the scaling state regime. These experiments are run in the International Space Station using an instrument designed for foams and equipped with video camera to observe the bubbles at the surface and multiple light scattering diagnostics to probe their bulk. This project is an international collaboration supported by the European Space Agency (ESA) and the Centre national d’études spatiales (CNES).
|International Space Station (ISS)
|Fluid Science Laboratory in the ISS
|Foam sample and speckle pattern produced by multiple scattering of coherent light backscattered by a foam
|These peaks reveal rearrangements inside the bubble packing
- Laboratoire de Physique des Solides, Université Paris-Saclay (D. Langevin, A. Salonen, E. Rio)
- Department of Physics, University of Pennsylvania, Philadelphia (D. Durian)
- Institut Navier, Université Gustave Eiffel, Champs-sur Marne (O. Pitois)
- Aberystwyth University, Royaume-Uni (S. Cox)
– “Soft matter dynamics: A versatile microgravity platform to study dynamics in soft matter”, P. Born, M. Braibanti, L. Cristofolini, S. Cohen-Addad, D. J Durian, R. Höhler et al, Review of Scientific Instruments, 2021, 92 (12), pp.124503. ⟨10.1063/5.0062946⟩. ⟨hal-03511925⟩
– “Aqueous foams in microgravity, measuring bubble sizes”, M. Pasquet, N. Galvani, O. Pitois, S. Cohen-Addad, R. Höhler, A. T. Chieco, S. Dillavou, J. M. Hanlan, D. J. Durian, E. Rio, A. Salonen and D. Langevin, Comptes Rendus Mécanique, Académie des Sciences (2023). Under press.