Spherically Symmetric Counterflow Turbulence in Open Geometry

期刊论文
发表日期：

2025年12月6日

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Tomáš Dunca,
Filip Novotný,
Marek Talíř,
Balázs Szalai,
Nikita Ustinov,
Ladislav Skrbek,
Emil Varga

摘要

We report preliminary results on spherical thermal counterflow generated by a small central heater in an open geometry, an open bath of superfluid He II, as closed cell experiments could have introduced artifacts such as overheating and boundary-induced flows. In order to eliminate them, we measure second sound attenuation in a plane-parallel resonator. Our results are at variance with the previous experiments in closed spherical cavity that showed plateau in the steady-state vortex line density and its inverse time decay, neither of which is observed presently. We find that in open geometry the vortex line density L increases steadily with counterflow velocity $v_\textrm{ns}$ $v_{ns}$ , displaying a crossover between $L \propto v_\textrm{ns}^2$ $L \propto v_{ns}^{2}$ typical for counterflow and $L \propto v_\textrm{ns}^{3/2}$ $L \propto v_{ns}^{3 / 2}$ , characteristic for the quasi-classical scaling.