STABILITY OF PLANAR REACTIVE FRONTS IN EXTERNAL FIELDS

Differential flows of species, which may arise in reactive systems due to external fields such as electric fields or pressure gradients, may significantly affect the characteristics and stability of propagating fronts. A generalized Kuramoto-Sivashinsky equation describing the dy namics of perturbations of a planar front in systems with differential flows is derived and analyzed. The analysis shows that a differential Bow parallel to the front may have either a destabilizing or a stabil izing effect. The effect of a lateral flow does not depend on its dire ction, while normal flows have a stabilizing effect when running in on e direction and a destabilizing effect in the other. These analytical conclusions are verified in numerical experiments with a model of a cu bic autocatalytic reaction. As a result of the instability, a periodic pattern of modulation appears on the front. In the case of lateral fl ow, the pattern drifts along the front. With normal how, the pattern i s stationary. The simulations show that both lateral and normal differ ential hows have a significant effect on the front velocity. [S1063-65 1X(98)08611-5].