581 / 2019-03-20 21:37:45

Two mode coupling of the ablative Rayleigh-Taylor instabilities

ablative Rayleigh-Taylor instability; two mode coupling; vorticity; bubble velocity

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The coupling and bubble evolution of two-mode ablative Rayleigh-Taylor instability (ARTI)
is studied numerically in two-dimensional geometry. Two kinds of mode combinations are investigated: a long and a short wavelength mode (long-short coupling), two short-wavelength modes (short-short coupling). For long-short coupling, the long-wavelength modes tend to dominate in the nonlinear phase, the short-wavelength mode enhances the total ARTI bubble vertex velocity. However, the enhancement of bubble vertex velocity does not increase monotonically with the initial perturbation of short-wavelength mode, own to the formation of enclosed bubbles. For short-short coupling, it forms a long-wavelength component in late-time stage which grows faster than each individual short-wavelength mode. Especially, when both modes are close to the linear cutoff, it will converge to the single-mode ARTI evolution in the nonlinear stages.