Droplet Mobilization via Interplay Between Capillary and Hydrodynamic Forces

We performed a two-dimensional finite element (FE) modelling of a non-wettable droplet driven by a pressure gradient through a constricted microchannel. The physical domain comprises a microchannel with sudden contraction mimicking pore-throat geometries. Phase field methodology is implemented to tackle the two-phase flow. A dimensionless formulation is adopted to computationally address the problem based on the commercial code of COMSOL Multiphysics. Simulations are performed for a range of capillary numbers and droplet length to understand the role of hydrodynamic and capillary forces in droplet mobilization. It is observed that increasing the droplet length assists droplet mobilization for a particular capillary number. Subsequently, droplets have been found to escape with increasing capillary number for a particular droplet length. Finally, we obtain a linear relationship between droplet length (L/w) and capillary number (Ca−1/3), which is very much consistent with the literature.