Bubble break up in turbulent flows
Orateur : Stéphane Perrard / ENS
Abstract : Liquid-gas flows play a central role in the transfert of low solubility gases, such as CO2, from the atmosphere to the ocean. Indeed, when a wave breaks, it traps large volumes of air that will fragment and generate sub-millimetric bubbles. The small bubbles in particular rise slower to the surface, and dissolve faster into the ocean. However, the distribution of bubble size, in particular for sub-millimetric diameters, remains an open question. In collaboration with Luc Deike, we have developed a dual approach, experimental & numerical to identify the physical processes at play in bubble fragmentation. Experimentally, we inject large controlled volumes of air within a turbulent flow, and we track the fragmentation dynamics. Numerically, we use direct numerical simulations of two phases flows, in idealised situations, such as a single bubble in an homogeneous and isotropic turbulent flow, to identify the mechanism leading to bubble break up and small bubble size productions. I will combine numerical and experimental data to explain the origin of the small bubble size distribution.
Date et lieu : le vendredi 7 octobre, 11h00, salle de séminaire IRPHE
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