Linear Stability of the Two-Dimensional Waves of Evaporating/Condensing Film Draining down an Inclined Plate
Ye Xuemin£¬Yan Weiping
(Department of Power Engineering, North China Electric Power University, Baoding 071003, China)

Abstract: The time evolution formulation of the two-dimensional waves of the evaporating or isothermal or condensing liquid films falling down an inclined wall is established for the film thickness with the collocation method based on the boundary layer theory and complete boundary conditions. Calculations show that the evaporation process destabilizes the film flow and the condensation process stabilizes the film flow, and the thermocaplillary takes a stabilizing effect in evaporation condition and an adverse effect in conden sation condition. For lower Reynolds number, the vapor recoil and thermocaplillary take dominant effects comparing to the inertia force in determining flow stability. For higher Reynolds number, stability is controlled by the inertia force.Present study indicates that the disturbance increases with increase of the Reynolds number and inclination angle, and decreases with increase of Ka numbers. Furthermore, the effects of liquid properties and inclination angle are always significant.
Keywords: wavy film;evaporating;condensing;linear stability