Airflow generated from drop impact on a dry substrate. Before impact, the drop creates an airflow in its wake. Immediately after impact, air from below the drop is deflected into a crown. The spreading liquid induces a vortex ring that is bound to the drop edge, which subsequently detaches and curls into an elegant roll. Winner of APS DFD Gallery of Fluid Motion Award. With Irmgard Bischofberger (postdoc) + Kelly W. Mauser (REU intern). Liquid drops do not splash if air pressure is too low! Why? Where does air play a role? We visualize the “invisible” air above a splashing drop as it spreads on a substrate. Seeing the invisible – air vortices around a splashing drop Sidney R. Nagel, University of Chicago, DMR

Nagel (top row, on right) has directed the University of Chicago REU program for women and under-represented minorities for the past ten years. This includes running all activities for the Physics Department as well as for the MRSEC and PREM. Kelly Mauser, (see last slide) REU 2012, worked in his lab last summer. She will enter CalTech graduate school in Physics this Autumn. Samantha Jones (3 rd row, 3 rd from right) worked in his lab this summer. She measured contact lines during splashing. The 2013 class of REU Interns in the Physics Department, MRSEC and PREM programs. Seeing the invisible – air vortices around a splashing drop Sidney R. Nagel, University of Chicago, DMR

Children of all ages enjoy the annual Physics with a Bang! lecture co-presented by the PI (shown on the right with an SF 6 “boat”). Bus loads of students attend -- even on a Saturday morning. It is so popular that two shows are needed to accommodate the crowds. High-speed video cameras used in the PI’s lab are used to play back in slow motion some of the phenomena that are too fast to see with the unaided human eye. Seeing the invisible – air vortices around a splashing drop Sidney R. Nagel, University of Chicago, DMR