The Invisible World of Droplets and more art by [13] Milad Bagheri

It is invisible in the sense that the details of this process cannot be seen by the naked eye but we were able to experimentally capture it using a high-speed camera with 20000 frames per second and simulate it using a diffuse-interface phase-field method. Obviously, the local features shown in this image cannot be captured through experiments but requires adaptive computation techniques and modern numerics.

What you are seeing in this image are two descending residual oil droplets that are ruptured from a central jet after an oil drop has hit the oil film at the bottom. These residual droplets will eventually merge and impact the already disturbed liquid film. On the right-hand side of this image you can see the Adaptive Mesh Refinement used in this study along with the velocity vectors colored with the velocity magnitude. And on the left-hand side of this image you can see the streamlines colored with the velocity magnitude which represents the flow field around the droplets. I also encourage you to attend my presentation to see the full animation compared to the experiment.