Numerical Studies of Stretching Liquid Bridges Between Two Spherical Solid Particles With Different Contact Angles

Numerical simulations of the governing Navier-Stokes equations are used to predict the rupture and liquid distribution of stretching liquid bridges between two equal-sized solid spherical particles with different liquid-solid contact angles. A commercial computational fluid dynamics (CFD) tool — FLUENT — is used. The effects of the capillary number and contact angle on the rupture distance and liquid transfer fraction are studied. The simulation results show that for particles with different contact angles, the rupture distance increases as the capillary number is increased; this is similar to the case of particles with identical contact angles. Also, it is shown that for quasi-static conditions, the rupture distance decreases as the difference between the contact angles is increased. Plots of the variations of the liquid transfer fraction with respect to the capillary number show three zones: (1) for high capillary numbers, liquid is almost equally distributed (dynamic zone); (2) for low capillary numbers, the liquid transfer fraction depends on the contact angles and more liquid is transferred to the particle with the smaller contact angle (quasi-static zone); (3) at intermediate capillary numbers, the curve connecting the above limiting conditions resembles an S-shape (transition zone), showing the dependency of the liquid distribution on both capillary number and contact angles. The trends are consistent with the experimental findings published in the literature.