Transport Phenomena in the Presence of Reactions: Definition and Measurement of Transport Coefficients

Abstract

Transport coefficients defined as constants of proportionality in flux-gradient relationships generally differ, in the presence of reactions, from coefficients of gradient terms appearing in balance equations such as the diffusion equation. Consequently, experiments sampling fluxes have to be interpreted differently from those sampling bulk properties. This difference is analysed here from the perspective of swarm experiments, which are surveyed and analysed with the help of a phenomenological transport theory. Standardisation in terminology and reporting of transport coefficients, along the lines suggested by Blevin and Fletcher (1984), is strongly supported.