Modeling capillary-driven particle agglomeration under shear in immiscible fluids using discrete multiphysics

In this study, we introduce a discrete multiphysics (DMP) model designed to simulate particulate systems where solid particles are immersed in a sheared primary fluid (water) and coated by an immiscible secondary fluid (oil). When dispersed particles come into contact with each other, the secondary fluid around the particles merges into a liquid bridge that induces particle agglomeration through capillary interaction. The model employs smoothed particle hydrodynamics to represent the primary liquid and the discrete element method for the solid particles. The secondary fluid is not explicitly modeled. Instead, we consider its impact indirectly by incorporating the attractive forces generated by the liquid bridges. These forces, arising when particles come into contact, are treated as additional attractive interactions within the DMP framework. Two liquid-bridge force models are selected for the simulations and validated against experimental observations in a granular collapse scenario. Subsequently, these validated models are integrated into the DMP framework to simulate particle agglomeration under shear, revealing three distinct agglomeration regimes based on varying Reynolds and elastocapillary numbers. These regimes are characterized by the formation of aggregates with diverse sizes and shapes, from elongated cylinders to spheroids. Results are presented in “agglomeration maps,” which facilitate the prediction of aggregate characteristics based on known Reynolds and elastocapillary numbers.