We present a one-dimensional model of reaction, diffusion and mixing i
n a two-dimensional flow. The model assumes that initially segregated
reactants are stretched and folded into a lamellar structure. Reaction
and diffusion are simulated within this one-dimensional lamellar arra
y. The lamellae are assumed to have a uniform thickness. Mixing is inc
luded as a single parameter i.e. the average stretch rate of the flow.
Results are compared with full two-dimensional simulations of the con
centration fields. Given the very simple nature of the one-dimensional
model and the complexity of the full system, remarkably good agreemen
t is obtained with a considerable saving in computational effort. For
a competitive-consecutive reaction the predicted yields agree to withi
n 6%. A typical one-dimensional simulation on a Silicon Graphics R5000
workstation takes around 1 min compared to 25 h on a 1024-node nCUBE
2 parallel computer for the concentration field simulations. The one-d
imensional lamellar simulations are not limited by the relative rates
of diffusion, reaction and advection, and are generally applicable to
complex two-dimensional and, in principle, three-dimensional flows. (C
) 1998 Elsevier Science S.A. All rights reserved.