Indian J. Phys. 81(11) 1177-1204 (2007) ^ . Diffusion and mobility driven instabilities in a reaction- diffusion system: a review SyedShahed Riaz and Deb Shankar Ray* Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India E-mail : pcdsr@rriahendra.iacs.in Abstract: Interplay of reaction and diffusion in a chemical system may lead to many interesting selforganization phenomena like stationary pattern, waves, spirals and targets etc. in spatially extended nonlinear dynamical systems far from equilibrium. One may trace their origin to different instabilities. In this review we have pre- sented a pedagogical exposition of two such instabilities relating to stationary pattern formation. The first one is the diffusion-driven instability, the Turing instability, arising from disparate diffusivities of two reacting compo- nents in a reaction-diffusion system under appropriate condition. The second one is the differential flow induced chemical instability which can be brought in by application of electric and magnetic fields. The analysis of instabilities and simulation of patterns have been carried out on chlorine dioxide-iodine-malonic acid reaction (CDIMA), which has served as an experimental testing ground for various theories in the last two decades. Keywords : Reaction diffusion system; pattern formation Hopf bifurcation, Turning instability PACS Nos : 82.40. Ck 7.54. +r 05.45. -a Plan of the Article 1. Introduction 2. Diffusion-driven Instability: theoretical and experimental aspects 3. Effect of electric field in generating Instability due to differential flow 4. Reaction-diffusion system in crossed electric and magnetic fields 5. Conclusion * Corresponding Author ©2007 IACS