Chemical Turing Pattern Formation Analyses: Comparison of Theory with Experiment

The development of oneand two-dimensional Turing patterns characteristic of the chlorite-iodide-malonic acid/indicator reaction occurring in an open gel continuously fed unstirred reactor is investigated by means of various weakly nonlinear stability analyses applied to the appropriately scaled governing chlorine dioxide-iodine-malonic acid/indicator reaction-diffusion model system. Then the theoretical predictions deduced from these pattern formation studies are compared with experimental evidence relevant to the diffusive instabilities under examination. The latter consist of stripes, rhombic arrays of rectangles, and hexagonal arrays of spots or nets. Here, starch (for the case of a polyacrylamide gel) or the gel itself (for a polyvinyl alcohol gel) serves as the Turing pattern indicator. The main purpose of these analyses is to explain more fully the transition to such stationary symmetry-breaking structures when the malonic acid reservoir concentration is decreased.