Numerical simulation of droplets, bubbles and waves: State of the art

This work presents current advances in the numerical simulation of two-phase flows using a volume of fluid (VOF) method, balanced-force surface tension and quad/octree adaptive mesh refinement (AMR). The simulations of the atomization of a liquid sheet, the capillary retraction of a liquid sheet and two- and three-dimensional wave breaking all for air/water systems are used to show the potential of the numerical techniques. New simulations of atomization processes for air/water conditions are allowing us to investigate the processes leading to the appearance of instabilities in the primary atomization zone in real conditions. For the retracting liquid sheet, the new simulations show that two different regimes can be encountered as a function of the Ohnesorge number. For large values, a laminar flow is encountered inside the rim and a steady state is reached after a quick transient state. For small values, a turbulent flow is generated inside the rim, which is responsible for large oscillations in the rim size and neck thickness. The breaking wave case study demonstrates the orders-of-magnitude efficiency gains of the AMR method.