Numerical simulation of vertical liquid-film wave dynamics

Abstract

In this paper the flow of liquid film on a vertical fiber is simulated using a multi-fluid model. It is demonstrated that nearly sinusoidal, as well as solitary waves can be simulated using an appropriate interface capturing model. Initial instabilities, which grow and cause wavy patterns, are introduced by disturbing the fluid inlet velocity. A constant disturbance frequency as well as white noise disturbance is used in numerical simulations. Waves travel on a substrate of constant height. The velocity of the wavy film expressed relative to a reference frame, which moves with film waves, shows recirculating motions. Bead velocities, frequencies, and amplitudes agree well with those reported in the literature. It is shown that disturbance frequencies above the so-called cutoff frequency and white noise disturbance lead to a “natural” like wave development, phenomena also observed in experiments.