Bubble bursting in a weakly viscoelastic liquid

Abstract

We study the bursting of bubbles in weakly viscoelastic liquids. The dissolved macromolecules form a monolayer at the water–air interface, influencing the bubble dynamics during the cavity collapse. For an optimum polymer concentration, the interfacial effects dampen short-wavelength waves, which intensifies the focusing of energy powering the jet ejection. This results in a significant increase (decrease) in the first-emitted droplet velocity (radius). The jet formation produces strain rates leading to a significant increase in the extensional viscosity. This extensional thickening reduces (increases) the first-emitted droplet velocity (radius). Bulk viscoelasticity produces a large difference between the velocity of the jet front at the tank surface level and the velocity of the first-emitted droplet. This droplet coalescence with others that are subsequently emitted, even for small polymer concentrations. Overall, viscoelasticity considerably hinders the ejection of small droplets, even for quasi-Newtonian liquids. The droplet emission is suppressed for smaller polymer concentrations when the bubble radius is decreased.