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Mechanics
In many cases, the processes proceeding in a nature and engineering, include liquid nonisothermal environments with deformable "liquid - gas " interface. Most simple, but widespread case of such multiphase currents is thin liquid films flowing down under action of gravity. The superficial forces in such current can dominate above volumetric one or be comparable with them. One of the found out phenomena is a formation of spatial self-organizing structure in thin local heating liquid film driven under action of gravity. It was found, that the local heating results in a local essential thickening of a film near to forward edge of a heater (liquid bump). At certain threshold density of a thermal flow the current is divided on the vertical jets following with certain length of a wave L and a thin film between them.
In [1] was established, that the formation of structures has a thermocapillary nature. There are many works (see, for example, [2]), in which the mathematical models of process are developed and the solutions are constructed, but the analysis was limited to cases of one heater. Here for the film flowing down on a flat substrate and on several rectangular heaters, located on it, the calculations of evolution of speed fields, temperatures and liquid – gas interface position are carried out. The calculations were carried out both at sudden inclusion of heaters, and in case of a gradual set by them of the given intensity for some final time. At construction of mathematical model the simplifications based on ordinal difference between quantities of contributions of the different factors in ratios were used. Thus was established, that at intensive local heating for process of heat transfer both mechanisms - convective and conductive are equally essential. Therefore energy equation was solved in complete production.
Calculations have shown, that the influence of a heater located above on a flow, on dynamics of a film and heat exchange near to the subsequent heaters rather considerably and consists in amplification of a local overheating and also in more significant deformations of a film surface.
This work has been supported by the Russian Foundation for Basic Research (project 04-01-00355).
References
1. Kabov O.A., Marchuk I.V. and Chupin V.M. Thermal Imaging Study of the Liquid Film Flowing on Vertical Surface with Local Heat Source// Russian Journal of Engineering Thermophysics. 1996. V. 6. No. 2. P.104-138.
2. Frank A.M. 3D numerical simulation of regular structure formation in a locally heated falling film// Europ. J. Mech. B/Fluids, 22(2003), 445-471.
Note. Abstracts are published in author's edition
Last update: 06-Jul-2012 (11:52:45)