Dynamic contact angles of droplets and capillary bridges

An experimental measurement of dynamic contact angles of droplets and capillary bridges is presented. The hysteresis of water retention in unsaturated granular materials during wetting and drainage cycles has been numerically found to arise from the dynamics of solid-liquid contact angles as a function of local liquid volume. The system established here aims to experimentally investigate the correlation between contact angle dynamics and liquid volume in both droplets and capillary bridges on different surfaces through the following scenarios: wetting and drainage of droplets and capillary bridges; surface tension and capillary force variation; and spontaneous contact angles and liquid volume arising from the evaporation of droplets and capillary bridges.