The aim of this paper is to explore how the effective thermal conductivityof small channels filled with superfluid helium II in the laminar regime separates from the classical Landau expression as the channel becomes shorter. The Landau expression is valid for fully developed Poiseuille flow for the normal component, and therefore is suitable for long channels. By taking into accountentrance effects, we show a transition from a heat flux proportional to ∆T /l(Landau regime) for long channels, to a heat flux proportional to l^(1/3) (∆T /l)^(2/3) for short channels.
|Titolo della pubblicazione ospite||Bollettino di Matematica pura e applicata|
|Numero di pagine||11|
|Stato di pubblicazione||Published - 2014|