Self-organization induced by the differential flow of activator and inhibitor

We have experimentally verified the prediction that a homogeneous steady state of an activator-inhibitor system can be destabilized by a differential flow of the key species, rather than by their differential diffusivity for Turing instability. Traveling waves are generated by a flow of Belousov-Zhabotinsky reactants through a tube containing ferroin immobilized on a cation exchanger. Without flow the system resides in a homogeneous steady state. This mechanism of spatiotemporal pattern formation avoids the restrictions of the Turing instability on the diffusion coefficients and can thus be expected to operate in a larger class of chemical, physical, and biological systems.