Formation, Rupture, and Healing of an Annular Viscous Film

Unlike conventional jet and drop breakup, which forms a cylindrical liquid column, the dripping of a viscous film will form a liquid annulus, which then ruptures and heals due to surface tension and the inner surface forms a retracting tip. We apply a one-dimensional model to analyze the thinning dynamics, which predicts a universal thinning curve and shows good agreement with experimental measurements. The shape of the tip is documented to be conical and the retraction speed is determined by the balance of viscous and capillary stresses. We also show that the drop contains an entrained bubble and possible formation of satellite bubbles in the healed thread.