Phase-field lattice Boltzmann equation for wettable particle fluid dynamics

Area of Science:

• Multiphase flow simulation
• Computational fluid dynamics
• Soft matter physics

Background:

• Simulating fluid-fluid-solid interactions is crucial for understanding phenomena like capillary forces and particle dynamics.
• Existing methods often face challenges in accurately capturing interface evolution and fluid-solid coupling.
• The lattice Boltzmann equation (LBE) and smoothed-profile method (SPM) offer potential for such complex simulations.

Purpose of the Study:

• To develop and validate a novel phase-field based LBE model for simulating wettable particle fluid dynamics.
• To accurately capture the evolution of fluid-fluid interfaces and fluid-solid interactions.
• To investigate the complex dynamics of multiple particles at an air-water interface.

Main Methods:

• A conservative Allen-Cahn equation LBE (CACE LBE) was developed to track fluid-fluid interfaces.
• A classical incompressible LBE was used to solve the flow field.
• The smoothed-profile method (SPM) represented solid particles, with fluid-solid forces calculated via direct force method.

Main Results:

• The CACE LBE successfully simulated benchmark cases: single particle at interface, capillary interactions, and cylinder sinking.
• Raft sinking of multiple cylinders revealed non-trivial, non-monotonic motion dynamics.
• Numerical predictions showed excellent agreement with theoretical solutions and experimental data.

Conclusions:

• The developed CACE LBE is a robust and accurate tool for simulating fluid-fluid-solid flows involving wettable particles.
• The model effectively captures complex interfacial phenomena and particle behaviors.
• This approach provides a reliable numerical framework for studying multiphase flows with complex geometries and interactions.