Spiral flow wave in a reaction-diffusion-convection system

The excitable Belousov-Zhabotinsky (BZ) reaction coupled with diffusion can exhibit a large variety of spatial patterns. In this letter, we report on superimposed spiral structures, providing evidence of a hierarchical self-organized order that connects two complex phenomena involving the coupling of a reaction-diffusion pattern with convection. A macroscopic propagating spiral flow wave (wavelength about 50 mm) is induced spontaneously by the preexcited reaction-diffusion structure of chemical spiral waves (wavelength about 1 mm). The pattern dynamics links two different hierarchical levels of structure formation in a nonlinear system.