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

P2691415: Vortex controlled 2D ejecta

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Authors

• Zainab Alayesh, King Abdullah University of Science and Technology
• Abdullah A. Alhareth A Alhareth, King Abdullah Univ of Sci & Tech (KAUST)
• Daniel Daniel, King Abdullah Univ of Sci & Tech (KAUST)
• Sigurdur T. Thoroddsen, King Abdullah University of Science and Technology
• Tadd Truscott, King Abdullah University of Science and Technology

DOI: https://doi.org/10.1103/APS.DFD.2024.GFM.P2691415

A 2.5 mm glycerin-water droplet (1200 kgm-3) impacting a vertical soap film (1065 kgm-3) produces a nearly symmetric two-dimensional ejecta pattern after colliding with the liquid pool formed by the film meniscus. Wake vortices stretch and shape the ejecta into a characteristic moustache-like form, leaving behind a swirl of colors that indicate varying thickness. Top-left inset: As the droplet descends through the soap film at low speed (1.2 ms-1) it takes on the shape of a flattened lens before merging with the meniscus (2 ms). The wake is symmetric, and the thin film ejecta emerges symmetrically with the characteristic moustache shape (8 ms). Top-right inset: At a higher impact speed (2.0 ms-1), the wake becomes asymmetric, with a trail of multiple large vortices (like a Kármán vortex street at 0 ms). These vortices break the ejecta symmetry, creating a complex pattern with multiple curls and turns. This system provides a fascinating example of droplet impact dynamics in a quasi-2D setup. Images were taken with a Nikon D850 camera (main image) and Phantom T3610 high-speed camera (insets) under a diffused white light at a 25º angle.