Less raw material, less energy: aerated solids are promising ecofriendly materials. These innovative materials are initially liquid foams, and the stability and apparent viscosity of these complex fluids need to be understood and controlled.
Context
Context
Experimental and theoretical developments recently improved our understanding of the flows at the soap film scale. However, the link between the effective visco elasticity observed at the foam sample scale and the flows measured at the film scale has not yet been identified. A better understanding of this multiscale problem is crucial to be able to predict the foam stability and dissipative properties as a function of the bubble size, liquid fraction and chemical formulation.
Experiments
The candidate will make the link between the macroscopic rheological properties of a liquid foam and the local flow recently desc ribed at the film scale. A direct comparison requires to use foam samples with large bubbles and a small liquid fraction. Shearing such a fragile sample at controlled stress will be a challenging but reachable aim, at the core of this project. These macros copic measurements will allow us to address for the first time the role of the disorder in the foam mechanical properties, by direct comparison with the strain/stress relationship recently determined for a single bubble [1].
Further developments
This project may lead to more advanced measurements, based on acoustic propagation of ultrasound in the foam [3], to obtain additional information of the film thickness distribution within the 3D sample, or to numerical and theoretical approaches to build and test a multi scale model for foam viscosity.
[1] Dynamical coupling between connected foam films: interface transfer across the menisci. A.Bussonnière, E. Shabalina, X. Ah Thon, M. Le Fur and I. Cantat. Phys. Rev. Lett. 124 p.018001 (2020)
[2] Local origin of the visco elasticity of a millimetric elementary foam. A. Bussonnière and I.Cantat. J. Fluid Mech. (2021)
[3] The acoustics of liquid foams. F. Elias, J. Crassous, C. Derec, B. Dollet, W. Drenckhan, C. Gay, V.Leroy, C. Nous, J. Pierre, A. Saint Jalme s. Current Opinion in Colloid & Interface Science, Elsevier,
2020, pp.101391.
Published on October 13, 2022 Updated on October 13, 2022
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