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Two-dimensional mapping of falling water film thickness with near-infrared attenuation

Dupont, J. ; Mignot, G. ; Prasser, H.-M

In: Experiments in Fluids, 2015, vol. 56, no. 5, p. 1-16

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    Titre
    • Two-dimensional mapping of falling water film thickness with near-infrared attenuation
    Auteur
    • Dupont, J.. Paul Scherrer Institut (PSI), Villigen, Switzerland
    • Mignot, G.. Paul Scherrer Institut (PSI), Villigen, Switzerland
    • Prasser, H.-M. Paul Scherrer Institut (PSI), Villigen, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Experiments in Fluids, 2015, vol. 56, no. 5, p. 1-16. Springer Berlin Heidelberg
    Autre version électronique
    Classification
    • Technologie, Sciences de l'ingénieur
    Identifiant OAI-PMH
    • oai:doc.rero.ch:331051
    Summary
    We have developed an optical technique for the two-dimensional mapping of water film thickness. The technique is based on infrared light absorption. A near-infrared camera is used to capture the radiation returning from a surface illuminated by a halogen lamp. The attenuation of the back-scattered radiation is used as a measure for the thickness of the water film covering the surface. The method was calibrated using well-defined liquid films between a glass plate and the surface. Series of instantaneous, two-dimensional thickness profiles of wavy turbulent free-falling films along a vertical wall were measured at a frame rate of 200Hz. The evolution of complex flow patterns with three-dimensional instabilities such as long waves and capillary waves was observed under isothermal conditions. For the validation of the method, simultaneous independent measurements were taken together with an electrical high-speed liquid film sensor.