An Improved, Free Surface, Topographic Technique

Article type: Research Article

Authors: Fouras, A. | Hourigan, K. | Kawahashi, M. | Hirahara, H.

Affiliations: Fluids Laboratory for Aeronautical and Industrial Research (FLAIR), Dept. Mechanical Engineering, Monash University, Wellington Road Clayton, Victoria 3800, Australia. Tel: +61-3-9905-9624/ Fax:+61-3-9905-9639, E-mail: [email protected] | Dept. Mechanical Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama-shi, Saitama 338-8570, Japan. Tel: +81-48-858-3443/Fax: +81-48-858-3711

Abstract: Current techniques of water wave visualization such as shadowgraphy and stereo photography are widely used but are deficient in many aspects. Refraction based visualization observes the bending of light as it traverses across a liquid-air interface. This work describes the continued development of techniques to measure the surface height of a liquid free surface. The method, Reference Image Topography, utilizes refraction of light at the free surface as a function of the local angle of that surface. Particle Image Velocimetry (PIV) software is used to evaluate apparent dislocations of the target image viewed through the free surface, which are approximately proportional to the surface angle. High-resolution images are presented of the dynamic surface topography for a point source and the shallow water flow around a vertical cylinder.

Keywords: Visualization, Free Surface, Topography, PIV

Journal: Journal of Visualization, vol. 9, no. 1, pp. 49-56, 2006