Breakup of low viscosity liquid jets and drops*

Breakup of low-viscosity liquid jets and drops in air has been of interest for over a century and is receiving increased attention because of emerging applications involving breakup of liquid metal jets which have viscosities μ comparable to but surface tensions γ and densities ρ much larger than water. The dynamics of breakup is governed by the Ohnesorge number Oh=μ/(ργR)^1/2 (R: nozzle or initial jet radius). When Oh«1, the thread initially thins as if it were inviscid and its minimum radius h_min obeys a universal scaling law h_min=A(γ/ρ)^1/3(t_b–t)^2/3 where t_b is the time t at which the thread breaks up and A≅0.717. As the interface overturns prior to breakup when Oh is sufficiently small, it has proven challenging to observe in simulations and experiments the value of the prefactor A obtained from theory and, furthermore, the transition of the dynamics as h_min→0 from the inviscid regime to a different scaling regime in which the effect of viscosity is no longer negligible. We use simulations to show that for sufficiently small Oh, the value of A predicted from computations agrees with the theoretical value to three decimal places and the inviscid power-law behavior can be observed over several decades in h_min as t_b–t→0. Transition out of the inviscid regime and into a viscous one is also demonstrated from simulations.