Rayleigh-Taylor mixing in supernova experiments

Abstract

We report a scrupulous analysis of data in supernova experiments that are conducted at high power laser facilities in order to study core-collapse supernova SN1987A. Parameters of the experimental system are properly scaled to investigate the interaction of a blast-wave with helium-hydrogen interface, and the induced Rayleigh-Taylor instability and Rayleigh-Taylor mixing of the denser and lighter fluids with time-dependent acceleration. We analyze all available experimental images of the Rayleigh-Taylor flow in supernova experiments and measure delicate features of the interfacial dynamics. A new scaling is identified for calibration of experimental data to enable their accurate analysis and comparisons. By properly accounting for the imprint of the experimental conditions, the data set size and statistics are substantially increased. New theoretical solutions are reported to describe asymptotic dynamics of Rayleigh-Taylor flow with time-dependent acceleration by applying theoretical analysis that considers symmetries and momentum transport. Good qualitative and quantitative agreement is achieved of the experimental data with the theory and simulations. Our study indicates that in supernova experiments Rayleigh-Taylor flow is in the mixing regime, the interface amplitude contributes substantially to the characteristic length scale for energy dissipation; Rayleigh-Taylor mixing keeps order.

Turbulent hydrodynamics experiments in high energy density plasmas: scientific case and preliminary results of the TurboHEDP project

“…The Pico2000 beam is used in bottom-up geometry [67] to acquire snapshots of RTI during the linear and highly nonlinear phases. We are interested in accurate measurement of the mixing zone width in the nonlinear stage [68] . The main advantage of a few weeks' campaigns on LULI is to test ideas for target designs and the capability to drive those targets in the relevant plasma regimes.…”

“…We leverage the results of LULI2000 and use theoretical scaling laws [7] to define the most relevant LMJ experiments to create turbulent HED plasmas relevant for young SNRs [68] . Extensive simulations are performed using realistic EOS for the brominated pusher and the foam [86] .…”

On the Rayleigh-Taylor unstable dynamics of three-dimensional interfacial coherent structures with time-dependent acceleration

“…This motion occurs even for an ideally planar interface and is supersonic for strong shocks. The growth of the interface perturbations is due to impulsive acceleration by the shock; it develops only when the flow fields are perturbed; its growth rate is subsonic and the associated motion is incompressible 1,2,6,[16][17][18][19][20][21][22][23] . The growth rate is constant initially and decays with time later.…”

“…As regards the general theory, we have to develop new approaches for nonequilibrium multi-scale RM/RT dynamics, capture symmetries of these RM/RT dynamics and identify properties of their asymptotic solutions 5,14,15,[25][26][27][28][29][30] . Experimental work requires one to meet tight requirements on the flow implementation, diagnostics and control 2,6,[20][21][22][23][24] . Simulations must employ highly accurate numerical methods, requiring massive computations in order to capture shocks, track interfaces, and accurately model small-scale processes [16][17][18][19][30][31][32][33][34] .…”

Key issues review: numerical studies of turbulence in stars

“…1. If the driving is sufficiently strong, an explosion may develop instead of steady-state convection, with the rising plumes becoming Rayleigh-Taylor (RT) unstable and, depending upon the structure, turbulent (Swisher, et al 2015). Expansion causes a "freeze-out" of the motions (Abarzhi 2010) and of the compositional structure, tending toward a spherical explosion (a Hubble flow).…”