A model for a differential-flow reactor is considered, based on cubic autoc
atalator kinetics in which the substrate is immobilized and the autocatalys
t flows through the reactor at a constant rate. Linear stability analysis s
hows that there is a critical flow rate above which the spatially uniform s
teady state becomes convectively unstable, Numerical simulations show that
this convective instability leads to the formation of a wave packet propaga
ting through the reactor. The nature of this wave packet depends on the flo
w rate and on the two cases that are identified for the kinetic parameter m
u, namely a generic case for general values of mu and when mu is close to t
he value which gives a Hopf bifurcation in the kinetic system. (C) 1999 Els
evier Science Ltd. All rights reserved.