Towards a generalized droplet fragmentation model

Modeling the aerodynamic breakup of a droplet has been of interest as this process is fundamental in determining the droplet statistics in many spray applications. Toward these efforts, we select a recent model proposed by Jackiw and Ashgriz ["On aerodynamic droplet breakup," J. Fluid Mech. 913, A33 (2021)] and attempt to enhance its suitability by proposing necessary modifications. In order to overcome the limitations of the original model, experiments are conducted systematically using the falling droplet method with liquids over a wide range of viscosities. Numerical simulations are also performed to second the experimental data. We observe that the droplet's passage through the jet shear layer delays the overall process by an amount equivalent to its residence time in the shear layer. Even though the initial deformation phase is relatively insensitive to the liquid viscosity, the final rupture time of the droplet and the child droplet statistics are found to be dependent on viscosity. These effects are quantified, and certain viscosity-dependent phenomena like viscous stretching are reported for further improvements in the model. In general, we show that the proposed modifications make the model more generic and comprehensive, improving its performance across a wide range of experimental conditions.