Fluid-Fluid Interfaces of Multi-Component Mixtures in Local Equilibrium.

Area of Science:

• Thermodynamics
• Fluid Mechanics
• Surface Science

Background:

• Understanding fluid-fluid interfaces is crucial for phase transitions and transport phenomena.
• Current models often rely on specific dividing surface definitions, which can introduce complexities.
• Non-equilibrium thermodynamics presents unique challenges for interface property analysis.

Purpose of the Study:

• To derive a new thermodynamic framework for fluid-fluid interfaces.
• To demonstrate the independence of intensive interface properties from the dividing surface location.
• To establish practical applications in determining interface temperature and chemical potentials.

Main Methods:

• Derivation of thermodynamic relationships for fluid-fluid interfaces.
• Application of the framework to one-component and multi-component fluid systems.
• Analysis of non-equilibrium conditions.

Main Results:

• Intensive properties of Gibbs interfaces are invariant to the dividing surface position.
• Surface tension can serve as a thermometer for one-component liquid-vapor interfaces.
• A consistent set of thermodynamic properties for multi-component surfaces was derived.

Conclusions:

• The invariance of interface properties simplifies thermodynamic analysis.
• The derived properties enable the construction of fluid-fluid boundary conditions for transport phenomena.
• This work impacts thermodynamic modeling of phase transitions and transport processes.