Drag Force on a High Porosity Aerogel in Liquid 3He

We discuss the drag force exerted on a high porosity aerogel in liquid 3He and its effect on sound propagation. The drag force is governed by distinct laws depending on the Knudsen number Kn, the ratio of the quasiparticle mean free path to a characteristic linear size of a body immersed in liquid....

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Bibliographic Details
Published in:Journal of physics. Conference series 2012-12, Vol.400 (1)
Main Authors: Takeuchi, Hiromitsu, Higashitani, Seiji, Nagai, Katsuhiko
Format: Article
Language:English
Subjects:
Aerogels
Attenuation
Drag
Elementary excitations
Physics
Porosity
Sound attenuation
Sound propagation
Temperature dependence
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Summary:We discuss the drag force exerted on a high porosity aerogel in liquid 3He and its effect on sound propagation. The drag force is governed by distinct laws depending on the Knudsen number Kn, the ratio of the quasiparticle mean free path to a characteristic linear size of a body immersed in liquid. In the liquid 3He-aerogel system, the characteristic length scale is aerogel strand diameter and both of the Knudsen limit (Kn ≫ 1) and the hydrodynamic limit (Kn ≪ 1) can be achieved in the normal phase by varying temperature. We show that the crossover between the two limits can be found as a drastic change in the temperature dependence of sound attenuation in the normal phase of liquid 3He in aerogel.
ISSN:1742-6588
1742-6596
DOI:10.1088/1742-6596/400/1/012071