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Interaction between buoyancy and diffusion-driven instabilities of propagating autocatalytic reaction fronts. II.
J D'Hernoncourt1, J H Merkin, A De Wit
1Nonlinear Physical Chemistry Unit and Center for Nonlinear Phenomena and Complex Systems, Faculte des Sciences, Universite Libre de Bruxelles (ULB), CP 231-Campus Plaine, 1050 Brussels, Belgium.
The Journal of Chemical Physics
|March 26, 2009
Summary
Numerical analysis reveals complex dynamics from interacting diffusive and Rayleigh-Taylor instabilities in autocatalytic fronts. These interactions lead to finger birth/death cycles and unique convective finger structures.
Area of Science:
- Chemical kinetics
- Fluid dynamics
- Nonlinear dynamics
Background:
- Autocatalytic traveling fronts exhibit complex behaviors influenced by diffusion and buoyancy.
- Rayleigh-Taylor (RT) instability and diffusive instability are key phenomena in such systems.
Purpose of the Study:
- To numerically analyze the nonlinear dynamics of autocatalytic traveling fronts.
- To investigate the interplay between diffusive and buoyancy-driven RT instabilities.
- To explore the influence of Rayleigh numbers and diffusion coefficient ratios on front dynamics.
Main Methods:
- Numerical simulations of autocatalytic traveling fronts.
- Analysis of fronts under varying gravity conditions (ascending/descending).
- Parametric study involving Rayleigh numbers (R(a), R(b)) and diffusion ratio (D).
Main Results:
- Observed complex dynamics including irregular finger birth and death cycles.
- Identified large convective fingers with tips deformed by diffusive instability.
- Demonstrated potential for slower diffusing species concentration to exceed fully reacted levels when D is small and RT instability is active.
Conclusions:
- The interaction between RT and diffusive instabilities creates rich nonlinear dynamics in autocatalytic fronts.
- Specific parameter regimes lead to unique finger structures and concentration behaviors.
- Conditions for experimental observation of these predicted dynamics are outlined.
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