ID 266

Direct Numerical Simulations of One- and Two-component Droplet Wall-Film Interactions within the Crown-type Splashing Regime

 

Abstract:

The scenario of an impacting droplet onto a wall-film is highly relevant in many technical systems. In combustion engines, for example, the interaction of fuel drops with oil wall-films can alter the pollutant emissions. In order to make reliable predictions for these systems, it is of crucial importance to gain a deeper insight into the underlying fluid dynamic processes of the observed phenomena. This however, can be difficult to achieve experimentally. For this reason, we investigate one- and two-component droplet wall-film interactions within the crown-type splashing regime by means of direct numerical simulation and present a comparison with experimental data. The simulations were performed with the multiphase code Free Surface 3D (FS3D), which is based on the Volume-of-Fluid (VOF) method and uses the Piece-wise Linear Interface Calculation (PLIC) method to reconstruct the interface. To distinguish between different liquids, additional VOF variables are introduced representing the volume fractions of each species within the liquid phase. The selected liquids are miscible and exhibit a significant viscosity ratio, but a similar density and surface tension. For the comparison with experimental data, the overall splashing morphology as well as the temporal evolution of selected crown parameters, such as crown height and crown angle are evaluated. The obtained results show that the impact morphology of both one- and two-component droplet wall-film interactions can be well reproduced. In addition, all evaluated crown parameters are in good agreement. With this positive validation, we are able to use numerical simulations with FS3D to gain a better understanding of the underlying fluid dynamic processes.