Dynamics and instability of liquid sheets and 2D drops

In a number of spray or atomization nozzles, liquid is ejected as a sheet---a film with two free surfaces---and then disintegrates into drops. The instability of liquid sheets is therefore of both practical and theoretical importance. Near the nozzle, the cross-section of a liquid sheet resembles a slender rectangle, possibly corrugated, with rounded ends. Surface tension causes the two nearly-circular ends to move toward each other or the slender two-dimensional (2D) drop to retract or contract. A number of authors have analyzed sheet retraction (e.g. Brenner and Gueyffier, PoF, 1999) and the possible breakup of the 2D drop during contraction (e.g. Burton and Taborek, PoF, 2007). In this talk, we present new insights into this problem by carrying out fully 2D free-surface flow calculations as well as solving a set of one-dimensional (1D) slender-sheet equations.