“…Flow within drops produces a 3D flow geometry that provides a useful, and physically-rich scenario for developing novel velocimetry methods. Further, drop research is central to many developing technologies including biological assays, (Garcia-Cordero and Fan, 2017;Guo et al, 2012;Kaminski and Garstecki, 2017) droplet and contact line PTV, (Bautista-Capetillo et al, 2014;de Cerqueira et al, 2023;Fischer et al, 2022;Humphrey et al, 1974;Kvon et al, 2020;Trantum et al, 2013) material actuators, (Malouin Jr et al, 2011;Vogel and Steen, 2010) adaptive optics, (Dean and Hirsa, 2015;López and Hirsa, 2008;López et al, 2005;Tyson and Frazier, 2022) and manufacturing (Gilani et al, 2021;Lanzerotti et al, 2021;Murr and Johnson, 2017;Scheithauer et al, 2017;Schuöcker et al, 2012) methods. The study of drop fluid dynamics is uniquely suited to experimentation in microgravity.…”