Size distribution of a drop undergoing breakup at moderate Weber numbers

The size distribution of child droplets resulting from a dual-bag fragmentation of a water drop is investigated using shadowgraphy and digital in-line holography techniques. It is observed that parent drop fragmentation contributes to the atomisation of tiny child droplets, whereas core drop disintegration predominantly results in larger fragments. Despite the complexity associated with dual-bag fragmentation, we demonstrate that it exhibits a bi-modal size distribution. In contrast, the single-bag breakup undergoes a tri-modal size distribution. We employ the analytical model developed by Jackiw & Ashgriz (J. Fluid Mech., vol. 940, 2022, A17) for dual-bag fragmentation that convincingly predicts the experimentally observed droplet volume probability density. We also estimate the temporal evolution of child droplet production in order to quantitatively illustrate the decomposition into initial and core breakups. Furthermore, we confirm that the analytical model adequately predicts the droplet size distribution for a range of Weber numbers.

Automated summary

The size distribution of child droplets resulting from dual-bag fragmentation of a water drop is studied using shadowgraphy and digital in-line holography techniques. The fragmentation of the parent drop contributes to small droplet atomization, while core drop disintegration leads to larger fragments. The dual-bag fragmentation exhibits a bi-modal size distribution, while the single-bag breakup shows a tri-modal size distribution. An analytical model developed by Jackiw & Ashgriz accurately predicts the experimentally observed droplet volume probability density for dual-bag fragmentation.