On the evolution of a retracting straight liquid sheet edge: experimental study

The evolution of the initially straight edge of a retracting liquid sheet is still a subject of debate. Theoretical and numerical studies have provided conflicting results, and experimental efforts have, to our knowledge, never been attempted owing to the difficulty in achieving a uniform edge. However, recent advances in experimental techniques, specifically those presented in detail in Poster \#72 of APS-DFD 2010 (H.C. Mayer and R. Krechetnikov), have allowed us to uniformly detach a soap film from a straight edge using an impulsively heated wire frame. The detachment, retraction, and breakup of soap films (h $\sim$ 10 $\mu$m) is analyzed using high speed photography. Owing to the Plateau border that connects the uniform film to the wire frames (wire diameter 25-250 $\mu$m) - a feature not present when rupturing films from a point - the early stages of retraction are dominated by a relatively large rim mass. We explore the phenomena at very early times (t $<$ 100 $\mu$s) associated with the birth of these detached films which may add complexity to the problem of determining what instability mechanism(s) are responsible for their breakup.