Rayleigh breakup of a charged viscous drop via tip-streaming (1902.08499v1)

Abstract: The experimental observation of D. Duft, T. Achtzehn, R. Muller, B. A. Huber, and T. Leisner, Nature 421, 128 (2003) on the sequential progression of the instability of a charged liquid drop points at the formation of a jet followed by the emission of progeny droplets as a crucial pathway of the Rayleigh fission process. In spite of considerable theoretical progress, a quantitative understanding of this breakup pathway through mathematical models has largely remained inconclusive. This limitation has mainly been due to the fact that the generally applied electrostatic boundary condition of the equipotential surface may not be valid near conical ends that experience a singularly fast dynamics near the point of fission. Considering this, we address the problem by invoking the surface charge dynamics within the framework of an axisymmetric boundary element method (BEM), in the viscous limit. The abandonment of the equipotential assumption gives rise to weak tangential electric stresses which turn out to be key the contributors to the emergence of a jet followed by formation of a progeny droplet. The simulations further predict that the size of the progeny droplet follows an inverse power-law scaling relationship with the conductivity of the liquid drop and the smaller sized progenies carry a charge close to its Rayleigh limit.