Schoepe, Wilfried (2023) Vortex Shedding from a Microsphere Oscillating in Superfluid He-4 at mK Temperatures and from a Laser Beam Moving in a Bose-Einstein Condensate. JOURNAL OF LOW TEMPERATURE PHYSICS, 210 (5-6). pp. 539-549. ISSN 0022-2291, 1573-7357
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Turbulent drag of an oscillating microsphere that is levitating in superfluid He-4 at mK temperatures, is unstable slightly above a critical velocity amplitude v(c). The life-time tau of the turbulent state is determined by the number n of vortices shed per half-period. It is found that this number is identical to the superfluid Reynolds number. The possibility of moving a levitating sphere through superfluid He-3 at microkelvin temperatures is considered. A laser beam moving through a Bose-Einstein condensate (BEC) (as observed by other authors) also produces vortices in the BEC. In particular, in either case, a linear dependence of the shedding frequency f(v) on Delta v = v - v(c) is observed, where v is the velocity amplitude of the sphere or the constant velocity of the laser beam above v(c) for the onset of turbulent flow: f(v) = a Delta v, where the coefficient a is proportional to the oscillation frequency omega above some characteristic frequency omega(k) and assumes a finite value for steady motion omega -> 0. A relation between the superfluid Reynolds number and the superfluid Strouhal number is presented that is different from classical turbulence.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | POTENTIAL FLOW; TURBULENCE; Quantum turbulence; Vortex shedding; Superfluid He; Superfluid Reynolds number; Superfluid Strouhal number; BEC |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Alumni or Retired Professors > Prof. Wilfried Schoepe |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 20 Feb 2024 09:46 |
| Last Modified: | 20 Feb 2024 09:46 |
| URI: | https://pred.uni-regensburg.de/id/eprint/56509 |
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