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Updated: Jun 30, 2026

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics
Published on: August 27, 2013
Dynamics in vibrofluidized beds: A diffusing wave spectroscopy study
Marlo Kunzner1, Christopher Mayo1, Matthias Sperl1,2
1Deutsches Zentrum für Luftund Raumfahrt (DLR), Institut für Materialphysik im Weltraum, 51170 Cologne, Germany.
None:
We demonstrate the densification of a granular model system of 130µm polystyrene spheres over time by shaking with varying excitation amplitudes or effective temperatures. This densification is quantified by the mean-square displacement (MSD), which is measured by diffuse wave spectroscopy (DWS) of a sinusoidally excited vibrating fluidized granular bed. The DWS method also extracts the inherent heterogeneous dynamics of the system in the bulk and at the wall. Through an empirical model-based extraction, we obtain the ballistic and diffusive time constants, as well as caging sizes, which were found to depend on temperature and density. The results obtained from this study reveal a subdiffusive power-law behavior in the MSD, indicating an arrest of motion and potentially a glassy system, especially in cases where the excitation is low to moderate compared to gravity. The extracted MSD caging sizes are two orders smaller than the Lindeman length found in colloidal systems.
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