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Seminario Bubble deformations and breakup in a turbulent flow

Data evento: - 14:30
Dove: Sala riunioni al secondo piano dell’edificio MO27.
Testo evento

Giovedì 28 novembre alle ore 14.30, presso la sala riunioni al secondo piano dell’edificio MO27, la Dott.ssa Alienor Riviere (Università Sorbonne) terrà il seminario dal titolo: "Bubble deformations and breakup in a turbulent flow".

 

Abstract:

In turbulent flows, bubble fate is controlled by the ratio between inertia and capillarity, namely the Weber number. There exists a critical Weber number which separates, in average, breaking from non-breaking bubbles. However, this limit is only defined in a statistical sense as it can happen that an a priori stable bubble encounters a large velocity or pressure fluctuation and breaks. In addition, real flows are rarely homogeneous and stationary. 

Using numerical simulations, we aim at quantifying the probability for a bubble to break in a given time window. To do so, we first study bubble deformations in a simplified flow geometry representative of the local flow geometry around bubbles: the uniaxial straining flow. 

We show that most of the dynamics can be reproduced by a 1D non linear oscillator on the oblate-prolate deformation mode. 

We then extend these results to a turbulent flow, by running direct numerical simulations of a single bubble in an homogeneous and isotropic turbulent flow. Similarly, we show that a 1D model is sufficient to describe most of bubble deformations, as well as predicting bubble lifetime. 

Data ultimo aggiornamento:
27/11/2024