Compressible Rayleigh-Taylor Instability with Large Temperature and Transport Property Contrasts

In environments containing high energy density (HED) plasmas such as Inertial Confinement Fusion (ICF) or supernovae remnants (SNRs), the Rayleigh-Taylor (RT) instability may occur under large contrasts in density, temperature and fluid transport properties that scale strongly with temperature. We examine fully resolved simulations of the 3D fully compressible RT instability at various temperature ratios and transport property configurations, providing a systematic analysis of how heat conduction, large variations in transport properties and sudden changes in transport properties can affect the development of a RT mixing layer. The idealized configuration of a hotter, less dense fluid pushing against a colder, denser fluid is considered. Previously presented simulation results are augmented with more extreme cases containing transport property magnitude ratios reaching up to 55.9.

For fluids with unequal molecular masses, heat transfer induces nonequal fluid expansion and contraction, which can significantly modify the density field, causing delayed instability growth or intensifying turbulent fluctuations in different regions of the flow. Both heat transfer and transport property contrasts induce a departure from self-similarity in instability growth rates and average profiles of flow statistics that have been commonly observed in isothermal RT simulations. Extreme misalignment between regions of mixing and regions of most intense turbulent activity, along with considerable non-homogeneity in many mixing statistics across the mixing layer, is observed. Time permitting, key differences between the 3D results with those of analogous 2D simulations will be highlighted.