Séminaire

Mardi 14 Décembre 2021 à 11h00.

Cavitation in micro-confined systems: experiments and simulations

'' ATTENTION au lieu inhabituel: Amphi Ampère
The nucleation and growth of vapor bubble in a stretched liquid medium is a common phenomenon along boat helices. Main studies on cavitation in water under tension concern then hydraulics, or acoustic conditions. Quasi-static conditions can also be used to generate negative pressures and cavitation by evaporation. They are observed naturally in the sap conducting network of trees (xylem) or in the catapult-like ferns sporangia where negative pressures lower than -100 bar are found [1]. It has also been observed in synthetic systems [2-3]. Both natural systems (trees and fern sporangia) are compartmented, and the way cavitation nucleation interacts between neighboring cells or cavities remain poorly studied. To do so, the first step is to understand the case of cavitation in a micro-confined enclosure where the water under tension is surrounded by solid walls.
I will first present our results on experiments in microfabricated systems made of water-filled cavities using soft lithography and pHEMA-MMA hydrogels. They allowed to characterize the acoustics emissions generated by the bubble’s dynamics [4]. Then I will show how molecular dynamics simulations can help to study this problem, especially when the wetting conditions of the walls are modified, focusing on the bubble’s nucleation [5].

[1] X Noblin, NO Rojas, J Westbrook, C Llorens, M Argentina, J Dumais. The fern sporangium: a unique catapult. Science 335 (6074), 1322-1322 (2012)
[2] T. D. Wheeler and A. D. Stroock, The transpiration of water at negative pressures in a synthetic tree, Nature 455 (7210), 208-212 (2008).
[3] The fast dynamics of cavitation bubbles within water confined in elastic solids. O Vincent, P Marmottant, SR Gonzalez-Avila, K Ando, CD Ohl. Soft Matter 10 (10), 1455-1461 (2014)
[4] C Scognamiglio, F Magaletti, Y Izmaylov, M Gallo, CM Casciola, X Noblin. The detailed acoustic signature of a micro-confined cavitation bubble. Soft matter 14 (39), 7987-7995 (2018)
[5] M Pellegrin, Y Bouret, F Celestini, X Noblin. Cavitation Mean Expectation Time in a Stretched Lennard-Jones Fluid under Confinement. Langmuir 36 (47), 14181-14188 (2020)
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