  We study the segregation of emulsions in decaying turbulence using direct
numerical simulations (DNS) in combination with the volume of fluid method
(VOF). To this end, we generate emulsions in forced homogeneous isotropic
turbulence and then turn the forcing off and activate gravitational
acceleration. This allows us to study the segregation process in decaying
turbulence and under gravity.
  We consider non-iso-density emulsions, where the dispersed phase is the
lighter one. The segregation process is driven by both the minimization of the
potential energy achieved by the sinking of the heavier phase, as well as the
minimization of the surface energy achieved by coalescence. To study these two
processes and their impacts on the segregation progress in detail, we consider
different buoyancy forces and surface tension coefficients in our
investigation, resulting in five different configurations. The surface tension
coefficient also alters the droplet size distribution of the emulsion.
  Using the three-dimensional simulation results and the monitored data, we
analyze the driving mechanisms and their impact on the segregation progress in
detail. We propose a dimensionless number that reflects the energy release
dominating the segregation. Moreover, we evaluate the time required for the
rise of the lighter phase and study correlations with the varied parameters
gravitational acceleration and surface tension coefficient.
