ON THE GROWTH OF NONEQUILIBRIUM SPATIAL CORRELATIONS IN A MODEL REACTION-DIFFUSION SYSTEM - THE EFFECT OF THE DIFFUSIVE FLOW RELAXATION

The mesoscopic description of a system with chemical reactions predict s that if the detailed balance condition is not satisfied then nonequi librium spatial correlations between concentrations of reactants may a ppear. The present work is concerned with the dynamics of their growth in a system which initially is well mixed. The discrepancy between th e theory based on the master equation, in which Pick's law was assumed for the diffusive flow, and molecular dynamics simulations performed for a model system of ''reacting'' hard spheres was found in our previ ous work. Molecular dynamics indicates front-like expansion of correla tions towards their stationary form, whereas the theory supports more uniform growth at all distances. In this paper, we introduce the relax ation of the diffusive flow towards Fick's law based on the Langevin a pproach in order to explain the front-like expansion of the spatial co rrelations.