Lattice Boltzmann model for capillary interactions between particles at a liquid-vapor interface under gravity.

Area of Science:

• Computational physics
• Fluid dynamics
• Interfacial phenomena

Background:

• Simulating particle-interface interactions is crucial for understanding phenomena like flotation and emulsion stability.
• Existing methods often struggle to accurately capture the complex interplay between particles, interfaces, and external forces like gravity.
• The lattice Boltzmann method (LBM) offers a powerful framework for mesoscopic simulations of complex fluids.

Purpose of the Study:

• To develop and validate a novel computational technique for simulating wettable particles adsorbed at a liquid-vapor interface under gravitational effects.
• To integrate advanced LBM variants for accurate modeling of both solid particle dynamics and fluid interface behavior.
• To investigate capillary interactions, including flotation and immersion forces, between particles at the interface.

Main Methods:

• A hybrid computational approach combining the smoothed-profile lattice Boltzmann method (LBM) for solid particle dynamics and the free-energy LBM for liquid-vapor interface description.
• Simulation of five benchmark 2D cases: stationary drop, single particle with/without gravity, and two particles exhibiting flotation and immersion forces under gravity.
• Quantitative comparison of simulation outcomes with established theoretical predictions.

Main Results:

• The developed LBM technique successfully simulated a stationary liquid drop and single wettable particles at a liquid-vapor interface.
• Accurate reproduction of capillary flotation forces between two freely moving particles at the interface under gravity.
• Successful simulation of capillary immersion forces for two vertically constrained particles at the interface.
• Simulation results demonstrated excellent quantitative agreement with theoretical estimations.

Conclusions:

• The proposed computational technique effectively simulates wettable particles at liquid-vapor interfaces, even under gravity.
• The method accurately captures complex capillary interactions, providing a reliable tool for interfacial phenomena research.
• This validated LBM approach offers a promising avenue for future studies in multiphase flow and particle-interface dynamics.