Publication Date:
1983-05-01
Description:
The steady motion of a Newtonian fluid in a rectangular enclosure open on its upper side is considered under the action of thermocapillary forces due to surface-tension gradients along the free surface. An asymptotic solution, in the limiting case of the aspect ratio A→0, is found and discussed for the cases where the surface deformation may be neglected, that is for contact angles at the lateral walls equal to ½π and very small values of the crispation number. The flow field has also been analysed in a wide range of the governing parameters A, Mg, Cr, by a computational model particularly appropriate to simulate free-surface flows. For A ≪ 1 the numerical results confirm the behaviour predicted by the asymptotic theory, while for A ≫ 1 several characteristic features of the flow-field structure are emphasized. For increasing Mg, the surface layer under the free surface maintains in the mid-section a constant value, dependent only on A, and decreases together with the thermal boundary-layer thickness near the lateral walls. For increasing A, the motion remains confined in a region near the free surface; hence the overall Nu, starting from the pure conduction value (Nu→1 as A→0) inccreases with A, reaching a maximum, to tend again to unity as A→∞. The surface deformation, at least for very small values of the crispation number, seems to have a negligible influence on the qualitative aspects of the flow-field structure. © 1983, Cambridge University Press. All rights reserved.
Print ISSN:
0022-1120
Electronic ISSN:
1469-7645
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
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