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The effect of internal degrees of freedom and of a class of boundary conditions on inverted temperature profiles between evaporating and condensing parallel plates is considered. It is found that such inverted profiles are present also in the case of polyatomic species and for most (but not all) modifications of the boundary conditions.

Transient heat transfer in liquid helium is investigated both experimentally and theoretically in plane and cylindrical geometry in the range of parameters where superfluid turbulence appears to be important. The influence of the main flow parameters – heat flux, pulse duration, and rest time – on the temperature evolution is reported. At high heat inputs the mutual friction force related to the superfluid vortex lines leads to the formation of a temperature overshoot behind the propagating second-sound wave and must be looked upon as a macroscopic effect of microscopic quantum turbulence. The experimental results can be reproduced by a theoretical model when the mutual interaction force is expressed in terms of the vortex line density (VLD), and the Vinen equation, extended to include spatial dependence, is taken into account for its temporal evolution. Fair quantitative agreement between experiment and theory is obtained if the ratio of the temperature overshoot and the shock-wave amplitude is below about 4. At stronger heat inputs the agreement is only qualitative.

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The existence and uniqueness of solutions, in Sobolev spaces, of the initial boundary value problem, global in time for the set of equations describing the flow of a barotropic viscous gas is investigated. A proof is deduced only for the case of inflow into a bounded domain valid for small initial and boundary conditions.

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