Longitudinal instability of a liquid rim

We study the transverse instability of a retracting liquid rim using a long wavelength approximation model and full numerical simulations. We observe that the instability of the rim is driven both by the Rayleigh-Taylor mechanism because of the initial rim acceleration, and by the Rayleigh-Plateau one. The coupling between the rim and the sheet stabilizes the rim at long wavelength. Full numerical simulations are in good agreement with the model and the subsequent break-up of droplets is observed in the numerical simulations when the instability is strong enough.