WEAKLY NONLINEAR STABILITY ANALYSIS OF CONDENSATE FILM FLOW DOWN A VERTICAL CYLINDER

Weakly nonlinear stability theory is used to study the stability chara cteristics of condensate film flowing down the outer surface of a vert ical cylinder. The surface tension and the mass transfer due to phase change are taken into account at the liquid-vapor interface. A method of perturbation is applied for the solution and the results show that supercritical stability in the linearly unstable region and subcritica l instability in the linearly stable region exist. The lateral curvatu re of the cylinder has a destabilizing effect on the flow stability. T he curvature of the cylinder will intensify the instability of the fil m flow in comparison with that of the planar flow. A possible applicat ion of the present results to some aspects of the qualitative design o f a coating process is given. Copyright (C) 1996 Elsevier Science ltd.