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Reshock of Self-Similar Multimode Richtmyer--Meshkov Instability at High Atwood Number in Heavy-Light and Light-Heavy Configurations

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Richtmyer–Meshkov instability (RMI) promotes turbulent mixing and is seen across a variety of events ranging from supernova to inertial confinement fusion[4]. In particular understanding RMI is important for ICF where enhanced mixing tends to drive down the yield or reduce power output in energy applications. In many applications multiple shockwaves pass through the mixing layer, for instance due to reflections from the centre of a spherical capsule, thus causing further enhanced mixing
To the best of the author’s knowledge we present the first ever results for a simulation of very high Atwood number reshocked Richtmyer–Meshkov instability using high order accuracy 3D methods (5th order in space and 2nd time) at high resolution (512 x 512 x 860). First an initial shock passes from the heavy gas to the light gas and the simulation is run until the mixing layer achieves self-similarity. Two different reshock cases are then run, the first with the second shock passing from light-to-heavy (the opposite direction to the original shock) and the second with the shock passing from heavy-to-light. Both shock Mach numbers are calculated to give the same impulse to the layer.
These latest results are presented for visualisations of the flow fields, comparing and contrasting the effects of shock passage in al- ternating directions, as well as a comparison of reshock at high Atwood number with reshocks at more commonly tested Atwood numbers. Turbulent kinetic energy spectra are also examined as well as the nature of the turbulence across the layer, including nu- merous mixing parameters and the progress from a highly anisotropic flow to one with behaviour more analogous to homogeneous decaying turbulence as the layer becomes self-similar.

Author(s):

Mike Probyn    
Cranfield University
United Kingdom

Ben Thornber    
Cranfield University
United Kingdom