Direct Simulation on the Dynamics of Liquid Films Flowing Down a Fiber

Direct simulations on the dynamics of a liquid film coating on the outer surface of a vertical fiber are performed in the present paper. A domain mapping technique has been used on solving the Navier-Stokes problem in stream function form and predicts the dynamics of the various flow regimes with remarkable accuracy. We investigated the morphologies that develop in the coating flow down fiber and analyze the effects of Bond number and fiber diameter on the maximum liquid film height and drop speed. The results showed that the Bond number and fiber diameter have a significant effect on the instability. The transition between the Plateau-Rayleigh and convective regimes occurs at the conditions when the flow transitions from absolutely to convectively unstable.