TRAVELING WAVES IN AN OPEN CUBIC AUTOCATALYTIC SYSTEM

A continuous-flow, unstirred reactor (CFUR) is considered in which the reaction is purely cubic autocatalysis and in which the exchange of r eactants between the reactor and its reservoir is modelled by linear d iffusive interchange terms. The system is capable of supporting two, s table, spatially uniform stationary states. The possibilities of initi ating travelling waves of permanent form (front waves), in which the c oncentrations vary monotonically between these two stationary states i s, investigated. It is seen that the formation of front waves requires the dimensionless parameter delta = D-A/D-B (D-A, D-B being the diffu sion coefficients of reactant and autocatalyst, respectively) to be su ch that delta less than or similar to 4, a result confirmed by numeric al integrations of an initial-value problem. For values of delta large r than this, permanent-form waves are not initiated with a more comple x structure evolving in the initial-value problem. Here the forward-pr opagating front leaves behind a region in which oscillations in the co ncentrations of both species are observed. These individual oscillatio ns are spatially fixed with the region where this oscillatory response is observed propagating backwards into the region of spatially unifor m concentration.