Schweizer Marco, Öttinger Hans Christian, Savin Thierry
Department of Materials, ETH Zürich, CH-8093 Zürich, Switzerland.
Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
Phys Rev E. 2016 May;93(5):052803. doi: 10.1103/PhysRevE.93.052803. Epub 2016 May 16.
Interfacial thermodynamics has deep ramifications in understanding the boundary conditions of transport theories. We present a formulation of local equilibrium for interfaces that extends the thermodynamics of the "dividing surface," as introduced by Gibbs, to nonequilibrium settings such as evaporation or condensation. By identifying the precise position of the dividing surface in the interfacial region with a gauge degree of freedom, we exploit gauge-invariance requirements to consistently define the intensive variables for the interface. The model is verified under stringent conditions by employing high-precision nonequilibrium molecular-dynamics simulations of a coexisting vapor-liquid Lennard-Jones fluid. We conclude that the interfacial temperature is determined using the surface tension as a "thermometer," and it can be significantly different from the temperatures of the adjacent phases. Our findings lay foundations for nonequilibrium interfacial thermodynamics.
界面热力学在理解输运理论的边界条件方面有着深远的影响。我们提出了一种界面局部平衡的公式，它将吉布斯引入的“分隔面”热力学扩展到非平衡状态，如蒸发或冷凝。通过用一个规范自由度确定分隔面在界面区域中的精确位置，我们利用规范不变性要求来一致地定义界面的强度变量。通过对共存的气液 Lennard-Jones 流体进行高精度非平衡分子动力学模拟，在严格条件下验证了该模型。我们得出结论，界面温度是用表面张力作为“温度计”来确定的，它可能与相邻相的温度有显著差异。我们的发现为非平衡界面热力学奠定了基础。
