2016-12-07
13:00 at HCI J 2

Steepest entropy ascent in nonequilibrium thermodynamics

Guanchen Li

Virginia Tech, Blacksburg, United States

Thermodynamics has been very successful in explaining the properties of macroscopic systems in equilibrium and near-equilibrium states. Many thermodynamic concepts, including the canonical distribution and the Onsager relations, can be viewed as concise patterns in the collective behavior of individual particles at a more microscopic level. However, the application of these thermodynamic concepts as currently formulated requires assumptions of near-equilibrium or local-equilibrium behavior. Thus, the study of phenomena in the far-from-equilibrium or non-local-equilibrium realm still generally relies on an investigation of the mechanical processes (e.g., collisions) of individual quantum states or particles, an approach, which necessarily entails a heavy computational burden. To address this drawback, recent research has pursued taking advantage of the use of thermodynamic patterns of collective particle behavior even in the non-equilibrium realm in order to simplify model requirements and hence the computational burden via the inclusion of thermodynamic information. One approach, whose reach has recently been extended to cover all spatial and temporal scales from a practical standpoint, is a novel first-principles non-equilibrium thermodynamic-ensemble framework called Steepest-Entropy-Ascent Quantum Thermodynamics (SEAQT). Its equation of motion is able to predict irreversible state evolutions on the basis of a gradient dynamics in system state space (such as phase space or Hilbert or Fock space) without explicitly tracking the microscopic particle or quantum state mechanics. The advantage of this approach is not only computational but is one in which all of the laws of physics and thermodynamics are inherently satisfied. This talk demonstrates how many thermodynamic concepts (e.g., equilibrium state, intensive properties, the Gibbs relation, the Clausius inequality, and the Onsager relations) can be generalized fundamentally into the far-from-equilibrium realm using the SEAQT framework applied to the relaxation of a local, isolated system in non-equilibrium. This is followed by illustrations of its application to modeling the transient behavior of reactive systems, non-quasi-equilibrium thermodynamic cycles, local non-equilibrium transport at a solid-state interface, and biological systems.