77th Annual Meeting of the APS Division of Fluid Dynamics (November 24, 2024 — November 26, 2024)

P2691171: Shape Driven Droplet Fragmentation

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Authors

• Sandip Dighe, King Abdullah Univ of Sci & Tech (KAUST)
• Aqeel Almanashi, KAUST
• Nilamani Sahoo, King Abdullah University of Science and Technology
• Dilip Kumar Kumar. Maity, King Abdullah Univ of Sci & Tech (KAUST)
• Charbel Khoury, King Abdullah University Of Science And Technology (KAUST)
• Spencer Truman, King Abdullah University of Science and Technology
• Aditya Parik, Utah State University
• Som Dutta, Utah State University
• Tadd Truscott, King Abdullah University of Science and Technology

DOI: https://doi.org/10.1103/APS.DFD.2024.GFM.P2691171

Two freely falling water droplets (dia = 8 mm) instantaneously exposed to an upward air jet ( vrel = 15.3 m/s) can form completely different breakup behavior if their initial shape is different. The deformation of the droplets is shown in two temporal sequences from bottom to top (i.e., 35 ms). The left panel reveals a prolate droplet (longer than wide) expanding into a forward bag in the direction of the airflow, ultimately fragmenting into tiny droplets with a novel cascade-type breakup and a central solid cylindrical stamen. In contrast, the right panel reveals an oblate droplet forming a backward bag with a unique hollow bowl-like film. The outer bag collapses in multiple locations simultaneously forming satellite droplets, leaving behind the bowl for a short time. These back-lit images reveal a fascinating divergence in behavior when the initial droplet is different but the equivalent diameter Weber number is the same. These back-lit high-speed images (10 kfps) highlight the influence that droplet shape has on deformation and fragmentation and distinct droplet breakup morphologies, such as the forward bag and hollow-bowl film structures.