Dresden 2017 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

DY: Fachverband Dynamik und Statistische Physik

DY 33: Fluid Dynamics and Turbulence

DY 33.9: Vortrag

Mittwoch, 22. März 2017, 12:15–12:30, ZEU 160

Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop — Huanshu Tan¹, •Christian Diddens², Pengyu Lv¹, Hans Kuerten^1,2, Xuehua Zhang³, and Detlef Lohse^1,4 — ¹University of Twente, The Netherlands — ²Eindhoven University of Technology, The Netherlands — ³Royal Melbourne Institute of Technology University — ⁴Max Planck Institute for Dynamics and Self-Organization

While the evaporation of pure liquid droplets and binary mixture droplets has been intensively studied, the evaporation of ternary mixture droplets with different volatilities and mutual solubilities has not yet been explored. Here, we show that the evaporation of such ternary mixtures can trigger a phase transition and the nucleation of microdroplets of one of the components of the mixture. As a model system, we pick a sessile Ouzo droplet (as known from daily life) and reveal and theoretically explain its four life phases: In phase I, the spherical cap-shaped droplet remains transparent while the more volatile ethanol is evaporating, preferentially at the rim of the drop because of the singularity there. This leads to a local ethanol concentration reduction and correspondingly to oil droplet nucleation there. This is the beginning of phase II, in which oil microdroplets quickly nucleate in the whole drop, leading to its milky color that typifies the so-called Ouzo effect. Once all ethanol has evaporated, the drop, which now has a characteristic nonspherical cap shape, has become clear again, with a water drop sitting on an oil ring (phase III), finalizing the phase inversion. Finally, all water has evaporated, leaving behind a tiny oil drop.