Three-dimensional numerical investigation of the droplet detachment and retainment on a symmetric three-sphere cluster: The role of contact angle hysteresis

How the advancing angle, receding angle, and contact angle hysteresis window independently modulate the droplet detachment, retainment, and wetting dynamics on an irregular particle has received little attention. The dynamic mechanisms of droplet impact on a symmetric three-sphere cluster are systematically investigated using a validated three-dimensional phase-field lattice Boltzmann model. By regulating the advancing angle, receding angle, surface tension, impact velocity, and gas–liquid viscosity ratio, particular attention is paid to the macroscopic deformation and mass retainment behavior of the droplet during impact. Three flow patterns are identified. The advancing angle plays a dominant role in determining flow pattern transition, whereas the receding angle acts as a fine regulator of morphological parameters such as contact area, bubble entrapment, and droplet position within a given pattern. Droplet dynamics on curved surfaces are governed by the competition among inertia, surface tension, and gravity. The initial velocity controls the impact strength, surface tension determines the dominant driving regime, and viscosity exerts only a threshold-dependent influence within specific Bond and Weber number ranges. Three flow patterns are clearly demarcated in the flow pattern map and appear sequentially. By adjusting the contact angle parameters and physical properties, the desired flow pattern can be tailored to meet specific requirements for wetted area and droplet retainment volume, enabling targeted control of droplet behavior on complex curved surfaces.