Thermal Contact

Abstract: The concepts of temperature and entropy as applied in equilibrium thermodynamics do not easily generalize to nonequilibrium systems and there are transient systems where thermodynamics cannot apply. However, it is possible that nonequilibrium steady states may have a thermodynamics description. We explore the consequences of a particular microscopic thermostat-reservoir contact needed to both stabilize and measure the temperature of a system. One particular mechanical connection mechanism is considered in detail and a contact resistance is observed in the numerical simulations. We propose a microscopic mechanism to explain this effect for both equilibrium and nonequilibrium systems. These results emphasize the difficulty in identifying a microscopic expression for the thermodynamic temperature. It is evident that the kinetic temperature is not necessarily equal to the thermodynamic temperature, especially when used to define the local temperature.