Numerical Study on the Instability of Shear Liquid Films

Abstract Liquid film flow has a wide range of applications in the industrial field, such as membrane condensation in intensified heat transfer and thin film preparation processes. This paper simplifies the model to liquid film flow on a horizontal plane under constant shear influence, uses long-wave approximation analysis to derive formulas, and studies the nonlinear waves of liquid films at moderate Reynolds numbers using finite difference methods. The result suggests that the evolution of liquid film height is initially influenced by the flux at the initial moment; in the long term, it depends on surface tension and gravity, with surface tension consistently suppressing disturbances. When the gravitational direction is aligned with the normal vector outside liquid film, disturbances will continue to increase and lead to film rupture; conversely, disturbances will be suppressed.