Discontinuities in helium II

Helmholtz free energy function (A=U−ST)

external body force acting on the superfluid

superfluid acceleration (=∂ _t v _i ^s +v _k ^s u _i,k ^s )

density of supply of linear momentum to the superfluid

diffusive force of the superfluid (=G _i ^s −m ^s v _i ^s )

short notation for ∂ _t ρ ^s +(ρ ^s v _k ^s ), _k

heat flux vector per unit area per unit time

heat supply function per unit mass unit per time

entropy per unit mass of helium II

absolute temperature (> 0)

superfluid stress vector ( _i ^s =n _k σ _ki ^s )

internal energy per unit mass of helium II

superfluid velocity

total mass density

superfluid mass density

superfluid stress tensor