Role of viscosity in turbulent drop break-up

We investigate drop break-up morphology, occurrence, time and size distribution, through large ensembles of high-fidelity direct-numerical simulations of drops in homogeneous isotropic turbulence, spanning a wide range of parameters in terms of the Weber number, viscosity ratio between the drop and the carrier flow, where d is the drop diameter, and Reynolds number. For, we find a nearly constant critical, while it increases with (and) when 20$]]>, and the transition can be described in terms of a drop Reynolds number. The break-up time is delayed when increases and is a function of distance to criticality. The first break-up child-size distributions for transition from M to U shape when the distance to criticality is increased. At high, the shape of the distribution is modified. The first break-up child-size distribution gives only limited information on the fragmentation dynamics, as the subsequent break-up sequence is controlled by the drop geometry and viscosity. At high, a size distribution is observed for, which can be explained by capillary-driven processes, while for 20$]]>, almost all drops formed by the fragmentation process are at the smallest scale, controlled by the diameter of the very extended filament, which exhibits a snake-like shape prior to break-up.