Flow of superfluid liquid helium has been studied experimentally in a porous medium formed by packing fine powder into a hollow glass sphere. The experiments fall into two categories, (1) the study of torsional oscillations of such a sphere filled with helium II as a function of temperature, and (2) the study of persistent circulating flow of the superfluid in such a sphere as a function of temperature and angular velocity of preparation, using a gyroscopic technique. The results at low angular velocities are shown to be in accord with an analysis of the motion of the liquid based on the two-fluid model of helium II and indicate that the superfluid can exhibit dissipationless potential flow in a porous medium with circulation constants which are remarkably stable.
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Mehl et al. (1968) studied this question.
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