Osamu Sano, Akiko Ugawa and Katsuhiro Suzuki
Department of Applied Physics, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-0054, Japan
(Received November 19, 1999; Accepted December 15, 1999)
Keywords: Granular Layer, Vertical Vibration, Self-Organized Pattern, Parametric Excitation, Quasi-Crystal
Abstract. An experimental study of the pattern formation on the vertically vibrated thin granular layer is made under atmospheric pressure. The granules are dry glass spheres. The forcing frequencies, their relative amplitudes and phases are controlled. High-speed video imaging is used to study the phase diagram of the patterns and its formation processes. In addition to squares, stripes and hexagons, a pattern similar to quasi-crystal patterns is found.