Numéro |
J. Phys. III France
Volume 6, Numéro 7, July 1996
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Page(s) | 975 - 989 | |
DOI | https://doi.org/10.1051/jp3:1996166 |
J. Phys. III France 6 (1996) 975-989
Experimental Determination of the Geometry of Real Drops on Transparent Materials
J.G. Pieters1, J.M. Deltour2 and M.J. Debruyckere11 University of Ghent, Departement of Agricultural Engineering, Coupure Links 653, 9000 Gent, Belgium
2 Faculté Universitaire des Sciences Agronomiques de Gembloux, UER de Physique et de Chimie Physique, Avenue de la Faculté 8, 5030 Gembloux, Belgium
(Received 21 December 1995, revised 1 April 1996, accepted 16 April 1996)
Abstract
An experimental method for the determination of real drop geometries on transparent supports is developed. The method offers
the possibility to obtain the general form of a drop by using commonly available instruments, such as a photo camera with
bellow, a digitizer or a scanner. By means of this method, a set of isoclinal lines of the drop registered by a camera. By
integration, the map of isoclinal lines is then mathematically transformed into a relief-map of the drop, revealing all geometric
information about the drop profile. A trial and error method for the correction of the measuring equipment alignment errors
is also developed. For a series of 15 drops on a vertical PE film and whose geometries are determined by means of the above
mentioned method, light transmission and diffusion are then simulated. It is shown that the light transmittance of flat drops
is somewhat lower than the light transmittance for dry PE but much higher than for hemispherical drops. Light diffusion is
shown to be nearly independent of the drop shape. Nearly all the light is diffused in a small solid angle. For an evaporating
drop on a vertical PE film, the evolutions of the drop geometry and the light transmittance are followed in time. It is also
demonstrated that during evaporation, the drop becomes mainly flatter so that the light transmittance increases.
© Les Editions de Physique 1996