SPATIOTEMPORAL CATALYTIC PATTERNS DUE TO LOCAL NONUNIFORMITIES

Nonuniformities of properties, like activity and transport coefficient s, are common to catalytic systems and were evident in studies of spat iotemporal patterns. Under such conditions it is usually difficult to conclusively differentiate between the effects of spontaneous symmetry breaking and those due to nonuniformity. We analyze the dynamics of o ne-dimensional systems with single-variable or two-variable kinetics a nd space-dependent properties and show that these systems may admit st able stationary fronts, oscillatory fronts, source points, and unidire ctional pulses. Uniform systems, with similar properties, admit travel ing front and pulse solutions. Patterns in nonuniform systems are quit e similar to those in systems with a global interaction that induces s ymmetry breaking, and both can be classified by the sequence of phase plane spanned by the system. We also analyze The impact of global inte raction that preserves the symmetry and show that it may destroy the i nhomogeneity due to nonuniform properties. Uniform and globally intera cting systems admit reflection symmetry, and patterns may appear as sy mmetric pairs. Although this property would be a most discriminatory t est, certain difficulties may be encountered in its implementation in catalytic systems.