User:Konstantin Agladze/Proposed/Chemical waves

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The article will cover known phenomena of chemical waves. The article is under construction now and in no way represents the final product.

Coupling of non-linear kinetics with diffusion transport makes possible the phenomenon known as "chemical waves".

Chemical reactions which may exhibit "waves" in well stirred conditions (which corresponds to 0-dimensional case) usually show bistability or oscillations. Waves or patterns can be observed if reaction occures in non-stirred condition, or only slow laminary currents present in the system. The simplest case of chemical wave is propagating wave front, when the system undergoes transition from state 1 to state 2. “Grass fire”. Phase transition of the first order. Oscillatory systems may produce propagating “pulses”: wave front propagates (transition from state 1 to state 2) and it is followed by the “recovery” (systems comes back from state 2 to the state 1). In this case state 1 may be referred to as "resting" state and state 2 as an "excited" state. Such a system may exhibit many waves and particular wave sources are “targets” and spirals. The simplest model for the wave-producing chemical system is often called "activator-inhibitor" system and the simplest mathematical model for it is Fitz-Hugh- Nagumo model. The most picturesque and well known example of chemical waves is waves in Belousov-Zhabotinsky reaction discovered by Zhabotinsky and Zaikin in 1970. Generally, waves are observed if diffusivity of inhibitor is not exceeding diffusivity of activator. In the case of substantially larger diffusion coefficient of inhibitor, wave propagation may become unstable and might give way to stationary or Turing structures. The Turing structures were discovered in Chlorite - Iodide - Malonic Acid (CIMA) reaction in 1989 by P. De Kepper and collaborators.

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