Complex fluids such as emulsions, suspensions, gels, or pastes exhibit interesting mechanical properties intermediate between solid and liquid [1]. Indeed, at short time for visco-elastic fluids or low stress for yield-stress fluids, they respond elastically, and at long time or large stress, they flow like a liquid. This makes them particularly interesting for industry (food, cosmetics, building). Moreover, in many applications such as coating, printing or imbibition, wetting properties of complex fluids play a crucial role.

In this talk, I will present the wetting properties of complex fluids in two situations: the spontaneous spreading of a drop made of a yield-stress fluid onto a solid surface and the forced imbibition of a hydrophilic yield-stress fluid into a hydrophobic porous medium. For simple fluids, these situations are classical and the wetting laws (Young-Dupré, Washburn, Laplace) are well established. Here I will study how the yield stress modifies these laws and highlight the strong impact of the dynamic history and the boundary conditions on the observed phenomena [2,3].

Contributors

Nicolas Bain, Anne-Laure Biance, Manon Bourgade, Loren Jorgensen, Mathieu Leocmach, Grégoire Martouzet, Loïc Vanel

References

[1] Bonn, D., Denn, M. M., Berthier, L., Divoux, T., & Manneville, S. (2017). Yield stress materials in soft condensed matter. Reviews of Modern Physics, 89(3), 035005.

[2] Martouzet, G., Jørgensen, L., Pelet, Y., Biance, A. L., & Barentin, C. (2021). Dynamic arrest during the spreading of a yield stress fluid drop. Physical Review Fluids, 6(4), 044006.

[3] Péméja, J., Géraud, B., Barentin, C., & Le Merrer, M. (2019). Wall slip regimes in jammed suspensions of soft microgels. Physical Review Fluids, 4(3), 033301.