Ribeiro, DanielaPanão, MiguelBarata, Jorge M MSilva, A. R. R.2023-01-022023-01-022022-07-11Daniela Ribeiro, Miguel Panão, Jorge Barata, André Silva, "Analysis And Visualization Of The Perturbations Imposed On The Liquid Film By Crown Sheet Collapse Or Closure", 20th International Symposium on Applications of Laser and Imaging Techniques to Fluid Mechanics, Lisboa, 11 a 14 julho 2022978-989-53637-0-4http://hdl.handle.net/10400.6/12558Bubble encapsulation is a phenomenon that results from droplet impact on a liquid film for very specific impact conditions. After splashing, the crown liquid sheet starts to bend inwards, and eventually, the jets at the top of the crown merge and form a perfect empty bubble. This bubble bursts due to the impingement of a secondary droplet that falls in the spherical dome or by reaching its critical thickness. However, bubble encapsulation is seldom reported in the literature. Due to that, this work focuses on understanding better its dynamics and formation mechanisms. By using a bottom perspective of the phenomenon, important information about its dynamics is disclosed. From the bottom shadowgraphs, the capillary waves and the perturbations imposed on the steady liquid film are clearly observed. From previous works, it was confirmed that its occurrence is systematic, so, one of the goals of this study is to realize how the impact conditions influence the phenomenon and if we can establish a criterion for its occurrence. Despite the scarce information about the phenomenon, there are some works about it that are focused on the cavity underneath the bubble. In this study, we observed the cavity and conclude that the cavity shape does not influence the bubble encapsulation phenomenon. Finally, the crown closure time was measured for a specific set of impact conditions and it was analyzed depending on the dimensionless thickness of the liquid film.engDroplet impactLiquid film thicknessCrown sheetconference object