Abstract
A fully three-dimensional linear stability analysis shows that ascending autocatalytic reaction fronts in vertical slabs are unstable to convection for large-wavelength perturbations at all finite values of the dimensionless driving parameter S=δ/ν. This parameter involves a fractional density difference δ between the unreacted and reacted fluids, the acceleration of gravity g, the slab width a, the kinematic viscosity ν, and the catalyst molecular diffusivity . Buoyancy dominates over the competing curvature dependence of the front velocity in a band 0<q< of unstable dimensionless wave numbers, with →S/24 as S→0 and →(S/4 as S→∞. As S→0, the perturbation with wave number =/2 has the maximum dimensionless growth rate =/48ν. For general S, the cutoff wave number is calculated using exact analytical solutions for the perturbed fluid velocity. The calculated results should be observable in experiments.
- Received 19 July 1993
DOI:https://doi.org/10.1103/PhysRevE.48.4378
©1993 American Physical Society