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Experiments on laminar film flow along a periodic wall

Published online by Cambridge University Press:  09 April 2002

M. VLACHOGIANNIS
Affiliation:
Department of Mechanical and Industrial Engineering, University of Thessaly, GR-38334 Volos, Greece
V. BONTOZOGLOU
Affiliation:
Department of Mechanical and Industrial Engineering, University of Thessaly, GR-38334 Volos, Greece

Abstract

Experimental results are reported on the structure of gravity-driven film flow along an inclined periodic wall with rectangular corrugations. A fluorescence imaging method is used to capture the evolution of film height in space and time with accuracy of a few microns. The steady flow is found to exhibit a statically deformed free surface, as predicted by previous asymptotic and numerical studies. Though usually unstable, its characteristics determine much of the subsequent non-stationary dynamics. Travelling disturbances are observed to evolve into solitary multi-peaked humps, and pronounced differences from the respective phenomena along a flat wall are noted. Finally, a remarkable stabilization of the flow at high Reynolds numbers is documented, which proceeds through the development of a three-dimensional flow structure and leads to a temporary decrease in film thickness and recession of solitary waves.

Type
Research Article
Copyright
© 2002 Cambridge University Press

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