Compressible single-fluid single-mode Rayleigh-Taylor instability

We study the single-fluid single-mode Rayleigh-Taylor instability (RTI) growth rate in the fully compressible regime in 2D and 3D using high resolution simulations. The single fluid set-up, where density differences arise from temperature variations, is important for the deceleration stage in Inertial Confinement Fusion. We systematically analyze the effects of perturbation Reynolds number ($Re_p$) and Atwood number ($A$).

Consistent with previous studies of the incompressible RTI [Wei and Livescu, Phys. Rev. E (2012), Ramaprabhu et al., Phys. Fluids (2012)], we find that at low to moderate Atwood numbers, the bubble re-accelerates and does not saturate at late times when $Re_p$ is large enough, contrary to potential flow theory prediction. The simulations further show that compared to 2D RT, RTI in 3D develops faster and re-accelerates at smaller $Re_p$ and larger $A$. At high Atwood number, while the bubble does not exhibit a clear re-acceleration regime over the times and $Re_p$ we analyzed, its velocity fluctuates with increasing amplitudes at higher $Re_p$. An analysis of the vorticity dynamics suggests that at high Atwood numbers, a re-acceleration regime would set in at sufficiently high $Re_p$.