Dresden 2017 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 16: Focus: Fundamental aspects of turbulent convection

DY 16.8: Talk

Tuesday, March 21, 2017, 12:00–12:15, ZEU 118

Droplet nucleation in two-phase thermal convection: A laboratory study — •Prasanth Prabhakaran¹, Stephan Weiss¹, Alexei Krekhov¹ und Eberhard Bodenschatz^1,2,3 — ¹Max Planck Institute f. Dynamics and Self-Organisation — ²Institute f. Nonlinear Dynamics, University Göttingen — ³Laboratory of Atomic and Solid-State Physics and Sibley School of Mechanical Aerospace Engineering, Cornell University, Ithaca (USA)

We investigate the nucleation and growth of liquid droplets in a Rayleigh-Bénard convection system, i.e., a horizontal fluid layer heated from below and cooled from above. The fluid consists of a mixture of sulfur hexafluoride (SF₆) and helium (He). Temperature and pressure are such that SF₆ exists in both, the vapor and the liquid phase while He is in the gas phase. Hot SF₆ vapor that rises from the bottom condenses inside the colder gaseous He/SF₆ mixture by homogeneous nucleation and forms small droplets that form clouds. We study the condensation process, as well as the dynamics of the droplet motion inside the gas phase visually using a high-speed camera. We found several instances, where droplet condensation occurs in the cold wake of larger falling droplets. This observation may suggest an additional mechanism for nucleation of droplets in atmospheric clouds.