2010 Volume 17 Issue 2 Pages 115-119
Some kinds of oil/water interfaces generate traveling wave along a glass surface. The aqueous and organic phases contain cationic surfactant, octadecyltrimethylammonium chloride, and an anionic chemical, respectively. This curious phenomenon has been studied by several researchers including the present authors. The spatiotemporal pattern formation may be useful for the direct energy conversion of chemical potential into work. We developed a simple model for the interfacial dynamics to reproduce rich patterns which were observed experimentally. Both of the experimental and theoretical considerations indicate that the traveling wave is produced by an excitable kinetics: Quasi-periodical oscillation due to the adsorption of cationic surfactant on glass followed by the desorption due to chemical reaction operates as a pace-maker of the interfacial motion. The pacemaker can give traveling waves. The present model reproduced several characteristics observed in experiments, such as both of concave and convex shape of the wave, the formation of wave trains with a fixed interval and the selection of traveling direction.
