On the conditions for stability of falling films subject to surface tension disturbances; the condensation of binary vapors

Abstract

Abstract Examination of available experimental information, including that on condensation of binary vapors, indicates that the Marangoni effect provides a consistent interpretation of falling film behavior, when surface tension disturbances are important. Criteria provided by the Marangoni effect are: d / db 0 for stability, where is surface tension and b film thickness, and d / db > 0 for instability; the latter is evidently a necessary but not sufficient condition. Methods are given for evaluating the sign of d / db in terms of the product of two factors, one characteristic of the system and one of the operation.