Superfluid Helium Evolution Phenomena (SHeEP)

abstract

The proposed research is concerned with the thermal-flow phenomena occurring in superfluid helium-4 in the vicinity of the λ transition. In spite of what is generally considered to be an accurate description of this remarkable liquid, which is the two-fluid approach developed by Landau and Khalatnikov, an alternative modelling technique has been proposed. It is based on the Extended Irreversible Thermodynamics theory, thus breaking with the assumption of two mutually interpenetrating phases, characteristic for the said model. Instead of considering velocities of individual phases, one obtains a macroscopic description based on barycentric velocity of the fluid and heat flux density as dependent variables, which is convenient from an empirical point of view. Furthermore, this approach has been proven to be consistent with the classic one. In the above framework the λ transition may be depicted using the order parameter as an additional dependent variable for which a separate evolution equation is provided. This description seems alluring, bearing in mind that second order phase transitions arise from symmetry breaking. The main goal of this research is to validate the accuracy of the mono-fluid approach in view of the dynamics of the λ transition.

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experiment year: 2016
number of drops: 32