Direct Numerical Simulation of a Buoyant Droplet Array

In many industrial and natural processes turbulent dispersion of immiscible phases occur. An industrial example is the process of steel making, where bubble flotation is used to remove inclusions which downgrade the quality of steel. An example from nature is the formation of droplets in clouds, where turbulent air influences the collision-coalescence rate. To gain a better understanding of droplet dynamics and turbulence modification in the clustering regime at Stokes number

St

∼1, proper modeling of coalescence and break-up is crucial. To be able to investigate these effects the number of deformable droplets should be relatively high and the problem has to be solved in an accurate and efficient way. The goal of our research is therefore to perform Direct Numerical Simulation (DNS) of a large number (∼10

3

) of inertial droplets in a turbulent carrier fluid, where coalescence and break-up is treated in a physical way. In general such simulations are expensive in terms of CPU, but in this work we show that our code scales well with an increasing number of deformable droplets and grid sizes.