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Universal Critical Velocity for the Onset of Turbulence of Oscillatory Superfluid Flow

Universal Critical Velocity for the Onset of Turbulence of Oscillatory Superfluid Flow The critical velocity v c for the onset of turbulent drag of small spheres oscillating in superfluid 4He is frequency dependent (ω/2π from 100 Hz to 700 Hz) and is described by $v_{c}=2.6\sqrt{\kappa \omega}$ , where κ is the circulation quantum. A qualitative analysis based on a recent theory of the onset of superfluid turbulence gives $v_{c}\approx \sqrt{8\kappa \omega/\beta}$ , where β∼1 depends on the coefficients of mutual friction. This agrees well with the data and implies that v c is a universal critical velocity that is independent of geometry, size, and surface properties of the oscillating body. This is confirmed by comparing our data on spheres with v c obtained with other oscillating structures by other groups. Numerical simulations indicate somewhat larger critical velocity, above which a rapid increase in vortex length is observed. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Low Temperature Physics Springer Journals

Universal Critical Velocity for the Onset of Turbulence of Oscillatory Superfluid Flow

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References (29)

Publisher
Springer Journals
Copyright
Copyright © 2008 by Springer Science+Business Media, LLC
Subject
Physics; Condensed Matter Physics; Characterization and Evaluation of Materials; Magnetism, Magnetic Materials
ISSN
0022-2291
eISSN
1573-7357
DOI
10.1007/s10909-008-9834-2
Publisher site
See Article on Publisher Site

Abstract

The critical velocity v c for the onset of turbulent drag of small spheres oscillating in superfluid 4He is frequency dependent (ω/2π from 100 Hz to 700 Hz) and is described by $v_{c}=2.6\sqrt{\kappa \omega}$ , where κ is the circulation quantum. A qualitative analysis based on a recent theory of the onset of superfluid turbulence gives $v_{c}\approx \sqrt{8\kappa \omega/\beta}$ , where β∼1 depends on the coefficients of mutual friction. This agrees well with the data and implies that v c is a universal critical velocity that is independent of geometry, size, and surface properties of the oscillating body. This is confirmed by comparing our data on spheres with v c obtained with other oscillating structures by other groups. Numerical simulations indicate somewhat larger critical velocity, above which a rapid increase in vortex length is observed.

Journal

Journal of Low Temperature Physics – Springer Journals

Published: Oct 8, 2008

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