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Transport Phenomena in Thermal Engineering. Volume 2

ISBN:
1-56700-015-0 (Print)

IMAGE ANALYSIS OF A SHADOWGRAM VISUALIZING SURFACE WAVES ON A FALLING LIQUID FILM

Takehiro Nosoko
Department of Mechanical Engineering, Keio University 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223, Japan; Department of Mechanical Engineering, University of the Ryukyus, Sembaru 1, Nishihara, Okinawa 903-01, JAPAN

Takashi Nagata
Department of Mechanical Engineering, University of the Ryukyus, Sembaru 1, Nishihara, Okinawa 903-01, JAPAN

Takao Shinzato
Department of Mechanical Engineering, University of the Ryukyus, Sembaru 1, Nishihara, Okinawa 903-01, JAPAN

Kenyu Oyakawa
Department of Mechanical Systems Engineering, Faculty of Engineering, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan

Tsunehiro Ohmija
Department of Mechanical Engineering, University of the Ryukyus, Sembaru 1, Nishihara, Okinawa 903-01, JAPAN

Minoru Nagai
Department of Mechanical Engineering, University of the Ryukyus, Sembaru 1, Nishihara, Okinawa 903-01, JAPAN

Abstract

Surface waves on a falling liquid film were visualized using shadowgraphy. A method of image processing was developed to extract images of wavefronts from a shadowgram. The wavefront image data was used to calculate the wave velocity and wavelength as a function of vertical and horizontal coordinates on the film surface. This method allows measurement of a newly defined variable, the wave distortion ratio which expresses the extent of distortion from a straight, horizontal line. The abundant two-dimensional results show the advantages of this image-processing method for investigations of surface waves on a liquid film.