Abstract
It is known that thermal diffusivity vanishes in fluid near a critical point. However, a quite rapid heat-transfer phenomenon was experimentally observed in such a state in some micro-gravity experiments. Later it was found that wave behavior caused by extremely large isothermal compressibility near a critical point enhanced heat transfer in a wave-like manner. Now, it is called the “piston effect” when a rapid and nearly isothermal heat transfer takes place in fluid near a critical point. In superfluid helium (He II), there exists a temperature wave called the “second sound wave.” Heat transport similar to the piston effect is thought to be caused due to the second sound wave in He II confined in a closed. A numerical simulation and an experiment were carried out to verify this. It was found that the numerical results agree well with the experimental data. We therefore designated the phenomenon as the “second-sound pseudo piston effect.”
