Breakup in stochastic Stokes flows: sub-Kolmogorov drops in isotropic turbulence

Deformation and breakup of drops in an isotropic turbulent flow has been studied by numerical simulation. The numerical method involves a pseudospectral representation of the turbulent outer flow field coupled to three-dimensional boundary integral simulations of the local drop dynamics. A statistical analysis based on an ensemble of drop trajectories is presented; results include breakup rates, the distribution of primary daughter drops produced by breakup events, and stationary distributions for drop deformation and orientation. Depending on the local flow history, drops may break at modest length or become highly elongated and relax without breaking. Drop deformation is the dominant mechanism of drop reorientation. The volume of the primary daughter drops, produced by a given fluctuation in flow strength, scales with the volume of the corresponding critical drop size for the fluctuation. A simplified description for the evolution of the drop size distribution, based on this scaling, is presented.