20.500.12556/RUL-190890 Direct observation of shockwaves, cavitation, and jetting inside liquid droplets during high-speed impact This study reports direct experimental observations of shockwave propagation and cavitation bubble formation inside liquid water droplets during high-speed impact (80 –180 m/s) on solid surfaces, together with jetting observed at the distal end of the droplet. Ultra-high-speed shadowgraph and angle-view imaging at 10 million frames per second resolved two distinct internal wave structures: a primary compression front (1500–2050 m/s), consistent with pressure-dependent corrections to the acoustic wave speed, and a secondary tension wave emerging approximately 500 ns later, generated by reflection at the curved water–air interface. The curved distal surface focuses converging rarefaction waves into a caustic region, leading to cavitation nucleation 1.2–1.5 µs after impact. The subsequent asymmetric collapse of these cavitation structures drives directed jetting from the distal end, with jet morphology dependent on droplet geometry: coherent jets for smaller spherical droplets (<2 mm) whereas spray-like ejection is typical for larger, elongated droplets (>2 mm). At the proximal end of the droplet, air is entrapped between the surface and the droplet, collapsing into a toroidal-shaped bubble that exhibits oscillations in the 0.5–1.8 MHz range. All presented results, including experimental data and accompanying analysis, provide benchmark validation data for computational models of compressible droplet impact. cavitation droplet impact shockwaves acoustic focusing high-speed imaging kavitacija trk kapljice udarni valovi akustično fokusiranje visokohitrostno slikanje true false true Angleški jezik Slovenski jezik Članek v reviji 2026-11-06 11:29:21 2026-11-06 11:29:28 2026-11-07 04:23:19 0000-00-00 00:00:00 2026 0 0 Str. 1-13 art. 108121 Vol. 134 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 532.528:004.932 1873-2828 10.1016/j.ultsonch.2026.108121 304216579 https://www.sciencedirect.com/science/article/pii/S135041772600386 1 ded2b2dc-d9cc-11f1-aea2-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=252672 Agrez_..._Direct_observation....pdf Agrez_..._Direct_observation....pdf 1 377C8FFE8851495494BD78618381523D 51e4524b24a21d6697dd5027ec04df208b0ed27864de66d6e908eca1fe4d07d2 0be21be1-d9cd-11f1-aea2-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=252675 Fakulteta za strojništvo 0 0 0