Modeling of capillary force between particles with unequal contact angle

When two particles with a thin liquid film are colliding toward each other, liquid films merge to form a pendular liquid bridge, which may induce a strong capillary force. The capillary force is determined by the particle size as well as contact parameters, such as liquid volume, contact angles of liquid on each particle, and the separation distance. Upon considering all these impacting factors, a general and explicit capillary force model was established in this study with a minimal energy method by using the software-Surface Evolver. The developed model was validated by comparing results with those obtained through an analytical expression and previous closed-form models. The developed capillary force model is capable of predicting the capillary force between two particles with different diameters and contact angles (≤50°) with an error of less than 15%