Topological reconnection of vortex bubble rings in two-phase flow

We investigate the reconnection of two vortex bubble rings using direct numerical simulations of the incompressible two-phase Navier–Stokes equations with a volume-of-fluid method and a continuum surface force model. At fixed Reynolds number and varying Weber numbers ( italic We We $\\textit{We}$ ) spanning surface-tension-dominated to inertia-dominated regimes, the reconnection dynamics are divided into four stages, including approach, interfacial reconnection, helicity transport and pinch-off. Low italic We We $\\textit{We}$ produces a larger reduction in interfacial area, leading to efficient reconnection and the formation of daughter bubbles. High italic We We $\\textit{We}$ stretches the interface into slender filaments, producing residual fragments and secondary vortical structures. Simulations show that vorticity begins to rearrange towards the contact region before reconnection occurs, with surface tension modulating vorticity redistribution and interfacial contraction as italic We We $\\textit{We}$ varies. These results relate italic We We $\\textit{We}$ to interfacial morphology and the resulting reconnection topology, connecting vortex dynamics and interfacial physics in two-phase flows.