Droplets and bubbles in homogeneous shear turbulence

The understanding of turbulent two-phase flows with bubbles and/or droplets is important in many natural and industrial processes, e.g. rain formation, liquid-liquid emulsion, spray cooling and spray atomization in combustors. In these flows the turbulence is altered by the droplet feedback on the surrounding fluid and by droplet-droplet interactions. We perform direct numerical simulations of a homogeneous shear turbulent flow with finite size droplets simulated by a volume of fluid method. Using a number of post-processing techniques, we will discuss the turbulence modulation in terms of statistics and flow structures. The turbulent flow is affected by the dispersed phase which damps its fluctuations; the multiphase flow reaches a statistically steady state where the turbulent production is balanced by the dissipation, and the number of droplets is on average constant. By studying the turbulent kinetic energy balance we show that the droplets are a sink of turbulent kinetic energy with increased dissipation rate density and reduced production. Finally, the merging and breakup processes are critically evaluated and compared with the theory by Hinze.