  We performed 3-D simulations of proton-rich material entrainment into
\czw-rich He-shell flash convection and the subsequent H-ingestion flash that
took place in the post-AGB star Sakurai's object. Observations of the transient
nature and anomalous abundance features are available to validate our method
and assumptions, with the aim to apply them to very low metallicity stars in
the future. We include nuclear energy feedback from H burning and cover the
full $4\pi$ geometry of the shell. Runs on $768^3$ and $1536^3$ grids agree
well with each other and have been followed for $1500\mathrm{min}$ and
$1200\mathrm{min}$. After a $850\mathrm{min}$ long quiescent entrainment phase
the simulations enter into a global non-spherical oscillation that is launched
and sustained by individual ignition events of H-rich fluid pockets. Fast
circumferential flows collide at the antipode and cause the formation and
localized ignition of the next H-overabundant pocket. The cycle repeats for
more than a dozen times while its amplitude decreases. During the global
oscillation the entrainment rate increases temporarily by a factor $\approx
100$. Entrained entropy quenches convective motions in the upper layer until
the burning of entrained H establishes a separate convection zone. The
lower-resolution run hints at the possibility that another global oscillation,
perhaps even more violent will follow. The location of the H-burning convection
zone agrees with a 1-D model in which the mixing efficiency is calibrated to
reproduce the light curve. The simulations have been performed at the NSF Blue
Waters supercomputer at NCSA.
