Numerical Study on Entrance Length in Thermal Counterflow of Superfluid 4 He

Hiromichi Kobayashi, Satoshi Yui, Makoto Tsubota

Research output: Contribution to journalArticle

Abstract

Three-dimensional numerical simulations in a square duct were conducted to investigate entrance lengths of normal fluid and superfluid flows in a thermal counterflow of superfluid 4 He. The two fluids were coarse-grained by using the Hall–Vinen–Bekharevich–Khalatnikov (HVBK) model and were coupled through mutual friction. We solved the HVBK equations by parameterizing the coefficient of the mutual friction to consider the vortex line density. A uniform mutual friction parameter was assumed in the streamwise direction. Our simulation showed that the entrance length of the normal fluid from a hot end becomes shorter than that of a single normal fluid due to the mutual friction with the parabolically developed superfluid flow near the hot end. As the mutual friction increases, the entrance length decreases. Same as that, the entrance length of the superfluid from a cold end is affected by the strength of the mutual friction due to the parabolically developed normal fluid flow near the cold end. Aside from the entrance effect, the realized condition of a tail-flattened flow is discussed by parameterizing the superfluid turbulent eddy viscosity and the mutual friction.

Original languageEnglish
JournalJournal of Low Temperature Physics
DOIs
Publication statusPublished - 2019 Jan 1

Fingerprint

counterflow
entrances
friction
Friction
Fluids
superfluidity
fluid flow
fluids
eddy viscosity
Hot Temperature
ducts
Ducts
Flow of fluids
Vortex flow
simulation
vortices
Viscosity
Computer simulation
coefficients

Keywords

  • Entrance length
  • HVBK model
  • Mutual friction
  • Superfluid
  • Thermal counterflow
  • Two-fluid model

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Numerical Study on Entrance Length in Thermal Counterflow of Superfluid 4 He . / Kobayashi, Hiromichi; Yui, Satoshi; Tsubota, Makoto.

In: Journal of Low Temperature Physics, 01.01.2019.

Research output: Contribution to journalArticle

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