Elisabeth Ghabache

On the physics of fizziness: How bubble bursting controls droplets ejection

Bubbles at a free surface usually burst in ejecting myriads of droplets. Focusing on the bubble bursting jet, prelude for these aerosols, we propose a simple scaling for the jet velocity and we unravel experimentally the intricate roles of bubble shape, capillary waves, gravity, and liquid properties. We demonstrate that droplets ejection unexpectedly changes with liquid properties. In particular, using damping action of viscosity, self-similar collapse can be sheltered from capillary ripples and continue closer to the singular limit, therefore producing faster and smaller droplets. These results pave the road to the control of the bursting bubble aerosols.

Evaporation of droplets in a Champagne wine aerosol

In a single glass of champagne about a million bubbles nucleate on the wall and rise towards the surface. When these bubbles reach the surface and rupture, they project a multitude of tiny droplets in the form of a particular aerosol holding a concentrate of wine aromas. Based on the model experiment of a single bubble bursting in idealized champagnes, the key features of the champagne aerosol are identified. In particular, we show that film drops, critical in sea spray for example, are here nonexistent. We then demonstrate that compared to a still wine, champagne fizz drastically enhances the transfer of liquid into the atmosphere. There, conditions on bubble radius and wine viscosity that optimize aerosol evaporation are provided. These results pave the way towards the fine tuning of flavor release during sparkling wine tasting, a major issue for the sparkling wine industry.

Frozen Impacted Drop: From Fragmentation to Hierarchical Crack Patterns.

We investigate experimentally the quenching of a liquid pancake, obtained through the impact of a water drop on a cold solid substrate (0 °C to -60 °C). We show that, below a certain substrate temperature, fractures appear on the frozen pancake and the crack patterns change from a 2D fragmentation regime to a hierarchical fracture regime as the thermal shock increases. The different regimes are discussed and the transition temperatures are estimated through classical fracture scaling arguments. Finally, a phase diagram presents how these regimes can be controlled by the drop impact parameters.

Liquid jet eruption from hollow relaxation

Using a model experiment, we explore the dynamics of inertial liquid jets arising from a gravitational cavity collapse. The focus of the study is to elucidate the link between both the dynamical and kinematical properties of the jet and the initial cavity geometry, for a wide range of physical parameters. We demonstrate that the jets exhibit shape similarity and reveal a robust relationship between the jet tip velocity and the initial cavity geometry, regardless of the details of the collapse process. We argue that this relation reflects a flow focusing mechanism, and we propose a simple model capturing the key features of the erupting jet velocity scaling. Finally, the relevance of these results to other jets occurring in e.g. large bubble detachment or wave impact on walls is discussed.