Particle tracking velocimetry applied to thermal counterflow in superfluid : Motion of the normal fluid at small heat fluxes
- National High Magnetic Field Lab., Tallahassee, FL (United States); Florida State Univ., Tallahassee, FL (United States)
- Univ. of Birmingham, Birmingham (United Kingdom)
This paper is concerned with thermal counterflow in superfluid 4He, particularly with the motion of the normal component at small heat fluxes when this motion is believed to be laminar. Recent experiments in which this motion is traced with micron-sized particles of solid deuterium show that the motion is not spatially uniform on a scale of order the spacing of the quantized vortex lines in the superfluid component. It is argued that this lack of uniformity has its origin in the fact that the force of mutual friction, which limits the thermal conductivity, is concentrated near the cores of the vortex lines. Possible effects of this concentration of force are discussed, and it is concluded that the experimental observations can be explained only if the vortex lines are arranged randomly in space, so that the observed lack of uniformity in the normal-fluid velocity can be regarded as being due partly to spatial variations in the vortex line density. Furthermore, problems remain, in that the form of the observed velocity correlation function has still to be understood.
- Research Organization:
- National High Magnetic Field Lab., Tallahassee, FL (United States); Florida State Univ., Tallahassee, FL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP); USDOE
- Contributing Organization:
- Dr. W.F. Vinen from University of Birmingham
- Grant/Contract Number:
- SC0020113
- OSTI ID:
- 1558801
- Alternate ID(s):
- OSTI ID: 1559073
- Report Number(s):
- DOE-FSU-20113; TRN: US2000252
- Journal Information:
- Physical Review Fluids, Vol. 4, Issue 8; ISSN 2469-990X
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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