Calculation of nanodrop profile from fluid density distribution

Area of Science:

• Interfacial Science
• Computational Physics
• Materials Science

Background:

• Determining the precise profile of liquid drops on surfaces is crucial for understanding phenomena like wetting and adhesion.
• Microscopic theories provide detailed fluid density distributions (FDDs), but extracting macroscopic drop shapes from them presents challenges.
• Existing methods often rely on approximations or specific assumptions about fluid interfaces.

Purpose of the Study:

• To evaluate two distinct approaches for calculating drop profiles from FDDs derived from microscopic theories.
• To introduce and validate a novel procedure (P3) for drop profile determination.
• To compare the effectiveness of the proposed procedure against established methods.

Main Methods:

• Examined two-dimensional (axisymmetrical) FDDs for fluids in contact with smooth solids or separated by a lubricant film.
• Approach 1: Sharp-kink interface approximation, minimizing total potential energy.
• Approach 2: Utilized nonuniform FDDs from density functional theory or molecular dynamics, employing procedures P1, P2 (using parallel lines), and the novel P3 (using radial lines).

Main Results:

• Procedure P1 uses equimolar dividing surfaces, while P2 assumes constant surface density.
• Procedure P3 involves extracting 1D FDDs along radial lines from a point within the drop and calculating the profile similarly to P1.
• Procedure P3 demonstrated superior performance, yielding more reasonable drop profiles compared to P1 and P2.

Conclusions:

• The proposed radial line procedure (P3) offers a more accurate and reliable method for determining drop profiles from microscopic FDDs.
• This work provides a valuable tool for researchers analyzing fluid behavior at interfaces.
• The findings have implications for understanding and modeling interfacial phenomena in various scientific and engineering applications.