Simulations establish self-similar Worthington jet collapse with r_j scaling as tau^0.63, driving local Weber number to infinity

The arXiv preprint by Sanjay et al. solves the axisymmetric Euler equations with free-surface boundary conditions for a conical cavity formed after bubble rupture. Local collapse is controlled solely by the opening semi-angle beta, yielding a universal interface shape when lengths are nondimensionalized by the predicted r_j(tau). This scaling holds independently of viscosity and far-field conditions once inertial focusing begins.

Earlier experiments on drop-impact Worthington jets reported similar thin spikes but lacked the temporal resolution to test the predicted exponent or the divergence of We_j. The new work closes that gap by showing that capillary regularization is overwhelmed at radii below 10 nm in water, directly implying the ejection of sea-spray aerosols whose initial size is set by the inertial singularity rather than by equilibrium surface tension.

The result connects to broader patterns in singular free-surface flows, including the conical shapes seen in bubble entrainment and electrospray. It suggests that aerosol generation models must incorporate this inertial-focusing regime rather than assuming a fixed minimum neck radius.