Convective effects on chemical waves. 1. Mechanisms and stability criteria

We consider the effects of convection on chemical waves in which density gradients result from the exothermicity as well as from the isothermal volume change of the reaction. If the signs of the enthalpy (ΔH) and volume (ΔV) of the reaction are opposite, then simple convection will occur, and the increase in the front propagation velocity will be equal to the velocity of the convective fluid flow. If the signs are the same, then simple convection will not occur. Instead multicomponent convection may be present, even though the overall density gradient may appear to be stable. The stability conditions for both mechanisms as functions of ΔH and ΔV and of the direction of front propagation (ascending, descending or horizontal) are analyzed. The effect upon the form of the wave front is also described. We also analyze convection in horizontally and vertically propagating trigger waves in the Belousov-Zhabotinskii reaction. © 1990 American Chemical Society.