A SIMPLE ISOTHERMAL MODEL FOR HOMOGENEOUS-HETEROGENEOUS REACTIONS IN BOUNDARY-LAYER FLOW .2. DIFFERENT DIFFUSIVITIES FOR REACTANT AND AUTOCATALYST

A simple model for homogeneous-heterogeneous reactions in stagnation-point boundary-layer flow, derived in a previous paper, is discussed in the case when the diffusion coefficients of the reactant and autocatalyst are different, characterized by the dimensionless parameter delta. The steady states of this system show the possibility of multiple solution branches through hysteresis bifurcations, the details of which are examined. Solutions valid for large and small of delta are obtained, and it is shown that, for large delta, it is the surface reaction which is the dominant effect, whereas for small values of delta, the homogeneous reaction becomes the most important mechanism.