Berlin 2008 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 29: Poster II

DY 29.58: Poster

Donnerstag, 28. Februar 2008, 16:00–18:00, Poster C

Dynamics of gas bubble in vibrofluidized wet granulates — •Kai Huang, Axel Hager-Fingerle, Klaus Roeller, and Stephan Herminghaus — Max Planck Institute for Dynamics and Self-Organization, D-37073, Goettingen

Recent studies on phase transitions of wet granulates show that the liquid-gas transition of wet granulates is dominated by the injected energy, because the hysteretic interaction of capillary bridges formed between particles introduces a characteristic energy scale. Between the liquid and the gas phase, there exists a co-existence regime where we always observe at least one stable gas bubble wandering around in the granular fluid. The gas bubble tends to reduce its surface and keep a circular shape, suggesting the existence of surface tension. Here we present an experimental study on the dynamic behavior of granular gas bubbles, including the nucleation, merging and vanishing processes. We use different methods to measure the velocity profile across the gas bubble. Inside the gas bubble, the velocity distribution is obtained by statistics on the track lengths of particles. In the fluid phase, the mean velocity is obtained by tracing Ruby particles illuminated with a green light source.