Rayleigh-Plateau Instability of a Particle-Laden Liquid Column: A Lattice Boltzmann Study

Colloidal particles known to be capable of stabilizingfluid-fluid interfaces have been widely applied in emulsion preparation, but their precise role and underlying influencing mechanism remain poorly understood. In this study, a perturbed liquid column with particles evenly distributed on its surface is investigated using a three-dimensional lattice Boltzmann method, which is built upon the color-gradient two-phase flow model but with a new capillary force model and a momentum exchange method for particle dynamics. The developed method isfirst validated bysimulating the wetting behavior of a particle on afluid interface and theclassic Rayleigh-Plateau instability and is then used to explore the effectsof particle concentration and contact angle on the capillary instability ofthe particle-laden liquid column. It is found that increasing the particleconcentration can enhance the stability of the liquid column and thusdelay the breakup, and the liquid column is most stable under slightlyhydrophobic conditions, which corresponds to the lowest initial liquid-gas interfacial free energy. Due to different pressuregradients inside and outside the liquid column and the capillary force being directed away from the neck, hydrophobic particles tendto assemble in a less compact manner near the neck of the deformed liquid column, while hydrophilic particles prefer to gather faraway from the neck. For hydrophobic particles, in addition to the influence of the initial liquid-gas interfacial free energy, the self-assembly of particles in a direction opposite to the liquid flow also contributes to opposing the rupture of the liquid column