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Direct Numerical Simulations of tilted Rayleigh-Taylor instability

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The tilted Rayleigh-Taylor instability, where the initial interface is not perpendicular to the driving acceleration, is investigated, for the first time, using Direct Numerical Simulations, on mesh sizes up to 1536^2×7200. In this configuration, the inclination of the initial interface results in a large-scale overturning motion, in addition to the buoyancy driven instability. Thus, this flow represents a unique turbulence unit problem, with two-dimensional mean flow and both shear and buoyancy production of turbulence. Two sets of simulations are presented: a) using a thin-tank domain in order to compare the results with the rocket-rig experiments of Smeeton and Youngs, and b) using a square cross-section domain. The results are used to examine the interaction between shear and buoyancy, including the parameters influencing the overturning and mixing, the role of initial conditions, and the differences in the turbulence
characteristics, at large and small scales, between the thin-tank and square cross-section domain cases.

Author(s):

Daniel Livescu    
Los Alamos National Laboratory
United States

Tie Wei    
New Mexico Tech
United States