Droplet size distribution in the fragmentation of liquid films via hole collisions

We study the fragmentation of pre-perforated thin liquid films using three-dimensional numerical simulations, focusing on droplet formation following hole collisions. An air–water system with film thickness e0=25 μm and varying hole spacings (dh/e0=3−20) is considered. The liquid bridge formed between colliding holes undergoes oscillation and stretching before breakup. The outcome depends on the spacing: for small dh, ligaments recoil into single droplets, while for larger dh, ligaments fragment via end-pinching and Rayleigh–Plateau (RP) instabilities. Droplet size distributions are compared with RP predictions and show improved agreement when a 40% reduction in ligament diameter due to stretching is accounted for. The results also compare favorably with experimental data from air-blasted films. This work provides new insight into the fundamental mechanisms controlling droplet formation from perforated films and highlights the critical role of hole spacing in determining ligament dynamics and droplet size distributions.