Investigation of the impact of a raindrop on oil slicks at the sea surface

The various phenomena related to the impact of a water droplet on a layer of oil located at the surface of salted water are investigated. These conditions mimic raindrops on the sea surface after oil spill, which generate both oil dispersion in the water, and marine aerosol. Direct Numerical Simulations (DNS) are performed, using the GERRIS solver: the local dynamic grid refinement capabilities make it especially appropriate for the present application where multiple interfaces and a large number of droplets and bubbles are obtained. As the motivation of this project is the characterization of the small scale mechanisms involved in the droplet splash, behavior of the oil layer, and aerosol formation, it is mandatory to be able to resolve the very small scales of the flow (typically a few microns) while ensuring a global computational cost in accordance with the current HPC resources. Validation of the numerical results is performed using the experimental data obtained previously at Johns Hopkins Univ. Then, the attention is focused on the analysis of the physical mechanisms that could not be extracted from the high speed visualization and the variation of the airborne droplets statistical size and behavior according to test conditions.