Abstract
We investigate numerically the contraction dynamics of a long air filament surrounded by liquid for a range of Ohnesorge numbers Oh. The contraction velocity rises to a maximum value U-max and then decreases due to the hydrodynamic drag force from the liquid medium. U-max follows a capillary-inertial scaling for low Oh while it shifts to a capillary-viscous scaling with increasing Oh. Our simulations reveal that contracting air filaments always first rupture via end-pinching mechanism before the Rayleigh-Plateau instability can develop.