On moving contact lines simulated by the single-component two-phase lattice-Boltzmann method

Area of Science:

• Fluid Dynamics
• Computational Physics
• Interfacial Phenomena

Background:

• Moving contact lines (MCLs) are crucial in multiphase flow phenomena.
• Simulating MCLs with the lattice-Boltzmann method (LBM) often requires slip models.
• The behavior of MCLs in single-component two-phase LBM (TP-LBM) without explicit slip is not fully understood.

Purpose of the Study:

• To investigate the characteristics of MCLs simulated by TP-LBM based on free-energy theory.
• To compare TP-LBM simulations with analytical solutions and understand the emergence of slip.
• To evaluate a novel method for regulating MCL motion in TP-LBM.

Main Methods:

• Utilized the single-component two-phase lattice-Boltzmann method (TP-LBM) with free-energy theory.
• Simulated MCL motion driven by evaporation and condensation.
• Compared simulation results with established analytical solutions for a benchmark problem.
• Applied a recently proposed LBM-based method for binary fluids to TP-LBM.

Main Results:

• Identified an effective slip length in TP-LBM simulations, directly proportional to the interface thickness.
• Demonstrated that MCL motion in TP-LBM does not require an explicit slip length.
• Showed that the novel method can effectively regulate MCL motion in TP-LBM.
• Confirmed that the new method significantly enhances TP-LBM's capability for simulating realistic two-phase flows with very small slip lengths.

Conclusions:

• TP-LBM inherently captures an effective slip length related to interface thickness.
• The adapted binary fluid method offers a powerful tool for accurate simulation of MCLs in TP-LBM.
• This approach improves the simulation of complex two-phase flows with minimal slip, advancing fluid dynamics research.