Showing papers on "Marangoni effect published in 1971"

The dynamics of thin liquid films in the presence of surface‐tension gradients

Abstract: The climbing of Marangoni films up vertical solid surfaces was investigated experimentally and theoretically. The system considered was a nonisothermal plate with its warm end partially immersed in a nonvolatile liquid. Observed film thicknesses and rates of climb were in agreement with an approximate hydrodynamic model obtained by assuming the supply capacity of the film to be rate limiting. The results of this study confirm the hypothesis is that previously observed liquid films formed against gravitational forces above equilibrium menisci are produced by surface-tension inequalities. It is pointed out that hydrodynamic processes cannot allow for the advancement of the leading edge of Marangoni films and a separate physicochemical process is required to explain spontaneous spreading of these films. Evidence is presented for the formation of much thinner primary films ahead of the secondary bulk films described by hydrodynamics. These primary films appear to be produced by a combination of multilayer adsorption and/or surface diffusion. The kinetics of these diffusional processes may limit spreading rates when surface-tension gradients become sufficiently large. Finally, the Marangoni films were found to be unstable in a manner hithertonot considered.

Buoyancy and surface-tension induced instabilities of fluid in open and closed vertical cylindrical containers

Abstract: Rayleigh and Marangoni types of instability of completely and partially confined fluid columns are considered The appropriate differential systems are reformulated in a form that fully accounts for the presence of the surrounding solid and free surfaces as well as for the surface-tension variations in the latter The present work is carried out under the assumption that the free surface, if present, is constrained to stay horizontal It is shown that if this assumption and the principle of exchange of stabilities hold the differential systems for both open and closed containers, govern no less than four dependent variables