Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 18: Focus: Droplets (joint session DY/CPP)

CPP 18.7: Vortrag

Montag, 12. März 2018, 17:15–17:30, BH-N 334

Droplets in moist Rayleigh-Bénard convection — Prasanth Prabhakaran, Alexei Krekhov, •Stephan Weiss, and Eberhard Bodenschatz — Max Planck Institute f. Dynamics and Self-Organisation, Göttingen, Germany

We report experiments on condensation patterns in a moist Rayleigh-Bénard convection experiment. We use Sulphur Hexaflouride (SF₆) at high pressure as the working fluid and the experiment is operated across the liquid-vapor coexistence line close and far from the critical point. A layer of liquid SF₆ forms at the warm bottom of the cell. From its surface, vapor evaporates and condenses at the cold top plate, where it forms a thin film that undergoes a Rayleigh-Taylor like instability. As a result droplets form due to pinch-off that fall back into the liquid layer. Depending on the pressure and the temperature difference between bottom and top, locations where droplet form can lie on an almost stationary hexagonal grid with a well defined wavelength. When the liquid level at the bottom plate is eliminated the droplets falling from the top plate levitate above the bottom plate due to Leidenfrost effect. Under appropriate conditions the Leidenfrost drops form large domains with multiple chimneys (multi-connected domains).