MechE Seminar : Bubble deformations and breakup in a turbulent flow
Event details
| Date | 23.05.2024 |
| Hour | 14:00 › 15:00 |
| Speaker | Aliénor Rivière |
| Location | |
| Category | Conferences - Seminars |
| Event Language | English |
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.
Bio:
Aliénor Rivière is a Ph.D. student at PMMH, ESPCI in France, where she studies the deformation and fragmentation dynamics of bubbles in turbulent flows. She obtained a M.Sc. from Sorbonne Université, as well as a M.Sc. from the École Normale Supérieure in Paris. Before that, she completed her B.Sc. at the École Normale Supérieure in Paris. Her research lies at the intersection between interfacial dynamics and turbulence, with a strong interest in nonlinear physics. Her approach combines numerical simulations of simplified configurations as well as direct numerical simulations and theory, to understand the mechanisms at play. She was awarded the 2023 Frenkiel Award for Fluid Mechanics.
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.
Bio:
Aliénor Rivière is a Ph.D. student at PMMH, ESPCI in France, where she studies the deformation and fragmentation dynamics of bubbles in turbulent flows. She obtained a M.Sc. from Sorbonne Université, as well as a M.Sc. from the École Normale Supérieure in Paris. Before that, she completed her B.Sc. at the École Normale Supérieure in Paris. Her research lies at the intersection between interfacial dynamics and turbulence, with a strong interest in nonlinear physics. Her approach combines numerical simulations of simplified configurations as well as direct numerical simulations and theory, to understand the mechanisms at play. She was awarded the 2023 Frenkiel Award for Fluid Mechanics.
Practical information
- General public
- Free