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We performed 3-D simulations of proton-rich material entrainment into\czw-rich He-shell flash convection and the subsequent H-ingestion flash thattook place in the post-AGB star Sakurai's object. Observations of the transientnature and anomalous abundance features are available to validate our methodand assumptions, with the aim to apply them to very low metallicity stars inthe future. We include nuclear energy feedback from H burning and cover thefull $4\pi$ geometry of the shell. Runs on $768^3$ and $1536^3$ grids agreewell with each other and have been followed for $1500\mathrm{min}$ and$1200\mathrm{min}$. After a $850\mathrm{min}$ long quiescent entrainment phasethe simulations enter into a global non-spherical oscillation that is launchedand sustained by individual ignition events of H-rich fluid pockets. Fastcircumferential flows collide at the antipode and cause the formation andlocalized ignition of the next H-overabundant pocket. The cycle repeats formore than a dozen times while its amplitude decreases. During the globaloscillation the entrainment rate increases temporarily by a factor $\approx100$. Entrained entropy quenches convective motions in the upper layer untilthe burning of entrained H establishes a separate convection zone. Thelower-resolution run hints at the possibility that another global oscillation,perhaps even more violent will follow. The location of the H-burning convectionzone agrees with a 1-D model in which the mixing efficiency is calibrated toreproduce the light curve. The simulations have been performed at the NSF BlueWaters supercomputer at NCSA.

Global non-spherical oscillations in 3-D $4\pi$ simulations of the H-ingestion flash