There is a rich body of work investigating the role of turbulence in particle collisions, with a particular emphasis on how it might accelerate the evolution of clouds in the atmosphere. We perform direct numerical simulations of isotropic turbulence with embedded droplets that coalesce upon collision (neglecting hydrodynamic interactions) to produce bigger droplets. As a consequence of coalescence, the droplet size distribution evolves over time from its monodisperse initial condition. Two case studies at initial Stokes number of 0.3 and at 0.7 show a broader distribution for the 0.7 case at lower percent coalescence, but the reverse trend at higher percent coalescence.
The simulation video shows a thin cross-section of a periodic isotropic turbulent cube with vorticity (orange) and particle density field (blue-white gradient).