Boundary conditions for the liquid-vapour interface of helium II

Abstract

Following the principles of the thermodynamics of irreversible processes of discontinuous system a theory of boundary conditions for the liquid-vapour interface of helium II is developed. Neglecting the influences of the coefficients of viscosity in the liquid and the gas, the surface tension of the liquid and surface currents, boundary conditions are inferred from the conservation laws of mass, momentum and energy including all non-linear terms. It is shown that two further boundary conditions for the net mass and energy transfer rates through the free surface of helium II can be obtained from the entropy balance. In the case of non-equilibrium processes occurring at the surface, net flows of mass and energy through the phase boundary result.