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Instability of film coating of wires and tubes
Author(s) -
Lin S. P.,
Liu W. C.
Publication year - 1975
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690210420
Subject(s) - coating , capillary action , materials science , mechanics , reynolds number , stability (learning theory) , instability , composite material , weber number , physics , computer science , machine learning , turbulence
Abstract The stability problem of the free coating of wires and tubes by withdrawal is formulated and solved. The necessary condition for the stability of the film coating is given explicitly in terms of the Reynolds number, wave number, the Weber number, and implicitly in terms of the withdrawal velocity. The outcome of the competition between the destabilizing capillary pinching and the stabilizing capillary restoring force associated with the film thickness variation is shown to dictate the stability of the film. The comparisons between the present theoretical results and the known experimental results for falling films and creeping annular threads of viscous liquids are good. A possible application of the present results to some aspects of the qualitative design of a coating process is given.