An energy-based equilibrium contact angle boundary condition on jagged surfaces for phase-field methods

Area of Science:

• Computational physics and materials science.
• Multiphase flow and porous media research.

Background:

• Voxel-based computational domains from micro-computed tomography (μCT) imaging of porous rock present challenges for phase-field models.
• Jagged surfaces in voxel approximations amplify errors in prescribed wetting angles for Cahn-Hilliard-Navier-Stokes models.

Purpose of the Study:

• To introduce an energy-based boundary condition for imposing equilibrium wetting angles in phase-field models on voxel-set domains.
• To develop a method to correct for surface roughness artifacts in μCT-derived computational domains.

Main Methods:

• An energy-based boundary condition was applied to the Cahn-Hilliard-Navier-Stokes phase-field model.
• Surface energy correction factors were introduced for fluid-solid voxel faces to account for surface area discrepancies.
• The discontinuous Galerkin method was used for discretizing model equations.

Main Results:

• The proposed correction factors effectively counterbalance the difference between voxel-set surface area and the underlying smooth surface area.
• The method ensures accurate simulation of wetting angles even on jagged voxel surfaces.
• The semi-analytical approach is adaptable to various numerical methods.

Conclusions:

• The developed surface energy correction method accurately imposes equilibrium wetting angles on voxel-based domains.
• This approach enhances the reliability of phase-field simulations for porous media derived from μCT data.
• The technique offers a robust solution for accurately modeling fluid-solid interactions in complex geometries.