Liquid redistribution upon the liquid-bridge rupture between two unequal particles with a minimal energy method

Numerical Investigation of Funicular Liquid Bridges between Three Spherical Grains in a Bidisperse Particulate System

Appropriate capillary effects are beneficial for controlling the wet powder performance and agglomerate formation. As water content rises, the funicular regime supplants the pendular regime as the predominant state in wet granular media. The displacement of grains leading to the stretching of funicular liquid bridges until rupture is an interesting and common phenomenon. Utilizing Surface Evolver software (an energy minimization approach), this work develops an efficient and accurate numerical model to describe liquid interactions among three spherical grains. The effects of liquid volume, contact angle, grain size ratio, grain-pair gap, and separation distance on the capillary forces and rupture distances are investigated. Notably, we present a modified closed-form equation for predicting the rupture distance of funicular bridges between three grains, which reflects the coupled effects of the contact angle, grain size, and liquid volume on rupture distance. This present study provides insights for incorporating capillary effects into mechanical models relying on microassembly composed of several grains in bidisperse particulate systems. Additionally, the numerical findings confirm some findings regarding the splitting of funicular bridges.

Capillary Forces between Concave Gripper and Spherical Particle for Micro-Objects Gripping

The capillary action between two solid surfaces has drawn significant attention in micro-objects manipulation. The axisymmetric capillary bridges and capillary forces between a spherical concave gripper and a spherical particle are investigated in the present study. A numerical procedure based on a shooting method, which consists of double iterative loops, was employed to obtain the capillary bridge profile and bring the capillary force subject to a constant volume condition. Capillary bridge rupture was characterized using the parameters of the neck radius, pressure difference, half-filling angle, and capillary force. The effects of various parameters, such as the contact angle of the spherical concave gripper, the radius ratio, and the liquid bridge volume on the dimensionless capillary force, are discussed. The results show that the radius ratio has a significant influence on the dimensionless capillary force for the dimensionless liquid bridge volumes of 0.01, 0.05, and 0.1 when the radius ratio value is smaller than 10. The effectiveness of the theorical approach was verified using simulation model and experiments.