Ken Sekimoto
Université Paris Diderot
Interplay between energy and momentum in stochastic phenomena beyond description Langevin Momentum transfer deficit due to dissipation

Since the last 15 years, the thermodynamic structure has been introduced in the Langevin level description. One reason that it was possible is that the energy is a scalar quantity. The linear frictional force and Gaussian random force were sufficient to describe the energy (heat) exchange between the system and environment. When, however, the momentum is involved in the system-environment interface, the Langevin description is no more satisfactory. It is because of the vectorial nature of the momentum. For example, in the analysis of the so-called "adiabatic piston," the rare but important collisions of hot gas particles from one side of the piston and the frequent but inefficient collisions of cold gas particles from the other side must be distinguished. To explain the physics behind the phenomena this system exhibits, correct understanding of the interplay between energy transport and momentum transport is crucial. In my talk I will describe the "momentum transfer deficit due to dissipation" (MDD), the concept we introduced recently. I will show how this concept helps to understand many stochastic phenomena like adiabatic piston, hitherto having been analyzed separately, from a universal physical point of view. I will also discuss an implication of MDD in the thermo-hydrodynamics of interacting gas having energy absorbing boundaries.
[References. Phys. Rev. Lett. 108, 160601 (2012); Phys. Scr. 86, 058508 (2012);in press, Acta Physica Polonica B (2013)]
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