General wetting energy boundary condition in a fully explicit nonideal fluids solver.

Area of Science:

• Computational Fluid Dynamics (CFD)
• Multiphase Flow Simulation
• Thermodynamics and Fluid Mechanics

Background:

• Accurate simulation of nonideal multiphase fluid flow is crucial for various engineering applications.
• Existing numerical schemes often face challenges with thermodynamic consistency and boundary condition stability, particularly at contact lines.

Purpose of the Study:

• To present an explicit finite-difference method for simulating nonideal multiphase fluid flow.
• To introduce and validate a general wetting energy boundary condition for improved thermodynamic consistency and stability at fluid-solid interfaces.

Main Methods:

• Employed Navier-Stokes equations for local density and momentum transport.
• Utilized the van der Waals equation of state for pressure computation.
• Developed and implemented a novel wetting energy boundary condition at the contact line.

Main Results:

• Validated the numerical scheme through static droplet and liquid-vapor separation simulations.
• The proposed wetting energy boundary condition alleviates instabilities observed with constant contact angle conditions near 0 and π.
• Achieved correct equilibrium contact angles and consistent contact line dynamics compared to stress-balanced methods, implicitly incorporating interface thickness.

Conclusions:

• The explicit finite-difference method provides a robust framework for simulating nonideal multiphase flows.
• The novel wetting energy boundary condition enhances numerical stability and thermodynamic consistency, offering an advantage over existing methods by implicitly handling interface thickness.