Imaging based on fluorescence has been used in the past to investigate, mostly in a qualitative manner, liquid films occurring in various applications. In the present paper, a simple quantitative experimental setup and the associated calibration procedure are detailed for a configuration involving Rhodamin B or Rhodamin 101 excited with light-emitting diodes (LEDs). The measurement procedure has been first validated for an open-channel flow considering different Reynolds numbers around 550 and has then been applied to the characterization of thin films, isolated droplets and rivulets. Using this technique the film thickness, film velocity and contact angle have been evaluated accurately for a variety of flow conditions.
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The support and helpful discussions with Róbert Bordás and Christoph Roloff are gratefully acknowledged. Furthermore, the authors would like to thank Nichia Corporation for material support with LEDs.
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Hagemeier, T., Hartmann, M., Kühle, M. et al. Experimental characterization of thin films, droplets and rivulets using LED fluorescence. Exp Fluids 52, 361–374 (2012) doi:10.1007/s00348-011-1232-x
- Contact Angle
- Inclination Angle
- Streamwise Velocity
- Static Contact Angle
- Dynamic Contact Angle