Local structure of liquid/vapour interfaces approaching the critical point

Area of Science:

• Thermodynamics
• Physical Chemistry
• Computational Fluid Dynamics

Background:

• Investigating high-temperature fluid interfaces is challenging.
• Distinguishing liquid from vapor and locating the phase boundary is crucial for understanding interface structure and fluctuations.

Purpose of the Study:

• To propose an alternative rationale for selecting the coarse-graining length scale in numerical simulations of fluid interfaces.
• To provide a more robust method for identifying the liquid phase boundary.

Main Methods:

• Developed a novel approach for determining the coarse-graining length scale.
• Required the average position of the local liquid phase dividing surface to match its flat, macroscopic counterpart.

Main Results:

• The proposed method offers a refined way to identify the liquid phase boundary.
• This approach provides additional insight into the structure of liquid/vapor interfaces.

Conclusions:

• The study suggests the existence of an additional length scale, beyond bulk correlation, that significantly influences interface structure.
• This new rationale enhances the understanding of fluid interface dynamics at high temperatures.