Rayleigh-Taylor unstable flames: The effect of two-mode coupling

We explore how adding a reaction to a Rayleigh-Taylor unstable interface affects the way that two short wavelength modes couple to generate longer wavelength modes. Using simulations, we identify five distinct flame growth solution types. Depending on the greatest common divisor of the wavenumbers of the two modes, the flame may stall, develop coherent pulsations, or even become a metastable traveling wave. We also compare our results with two-mode coupling in ablative and classical Rayleigh-Taylor and show that all three systems may follow the same mode coupling dynamics.