Vortex line density in counterflowing He II with laminar and turbulent normal fluid velocity profiles

Abstract

Superfluid helium is an intimate mixture of a viscous normal fluid, with continuous vorticity, and an inviscid superfluid, where vorticity is constrained to thin, stable topological defects. One mechanism to generate turbulence in this system is through the application of a heat flux, so called thermal counterflow. Of particular interest is how turbulence in the superfluid responds to both a laminar and turbulent normal fluid in the presence of walls. We model superfluid vortex lines as reconnecting space curves with fixed circulation, and consider both laminar (Poiseuille) and turbulent normal fluid flows in a channel configuration. Using high resolution numerical simulations we show that turbulence in the normal fluid sustains a notably higher vortex line density than a laminar flow with the same mean flow rate. We exam Vinen's relation, $\sqrt{L}=\gamma v_{ns}$, between the steady state vortex line density $L$ and the counterflow velocity $v_{ns}$. Our results support the hypothesis that transition to turbulence in the normal fluid is responsible for the TI to TII transition. We also consider the spectral properties of fluctuations of the superfluid vortices, which show a good agreement with previous experimental results.

14 pages, 12 figures, submitted to physics of fluids

References in corpus (6)

• Velocity Statistics Distinguish Quantum Turbulence from Classical Turbulence
• Bottleneck crossover between classical and quantum superfluid turbulence
• Quantum and quasiclassical types of superfluid turbulence
• Visualization study of counterflow in superfluid helium-4 using metastable helium molecules
• Turbulent velocity spectra in superfluid flows
• Energy cascade and the four-fifths law in superfluid turbulence

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