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arXiv · 0810.3191

Fluidization of granular media wetted by liquid $^4$He

K. Huang·M. Sohaili·M. Schröter·S. Herminghaus
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Abstract

We explore experimentally the fluidization of vertically agitated PMMA spheres wetted by liquid $^4$He. By controlling the temperature around the $λ$ point we change the properties of the wetting liquid from a normal fluid (helium I) to a superfluid (helium II). For wetting by helium I, the critical acceleration for fluidization ($Γ_c$) shows a steep increase close to the saturation of the vapor pressure in the sample cell. For helium II wetting, $Γ_c$ starts to increase at about 75% saturation, indicating that capillary bridges are enhanced by the superflow of unsaturated helium film. Above saturation, $Γ_c$ enters a plateau regime where the capillary force between particles is independent of the bridge volume. The plateau value is found to vary with temperature and shows a peak at 2.1 K, which we attribute to the influence of the specific heat of liquid helium.

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K. Huang, M. Sohaili, M. Schröter, S. Herminghaus. 2009-01-12. Fluidization of granular media wetted by liquid $^4$He. https://doi.org/10.1103/physreve.79.010301

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