Numerical framework for inferring the viscosity of high-pressure condensed matter using hydrodynamic instabilities and shock-driven acoustics

The transport properties of high-pressure condensed matter, particularly viscosity, play a critical role in understanding planetary interiors, dynamic compression phenomena, and inertial confinement fusion. Despite their importance, experimental measurements of viscosity at extreme pressures remain limited. Recent experiments on OMEGA-EP employed laser-driven shocks to induce the Richtmyer–Meshkov instability at an epoxy-MgO interface [1], enabling viscosity inference through comparison with high-fidelity simulations. In this work, we present the numerical framework used to interpret such experiments, emphasizing the sensitivity of viscosity inference to material properties such as the epoxy equation of state, epoxy viscosity, and strain-rate effects. We also highlight how the experimental configuration unintentionally enables measurement of the epoxy’s effective viscosity. Finally, we describe ongoing work using acoustic wave decay as an independent viscosity diagnostic and present preliminary simulation results supporting its feasibility.

[1] T. M. Perez, S. C. Dick, R. F. Smith, P. M. Celliers, J. H. Eggert, S. J. Ali, E. Johnsen, J. K. Wicks, Low viscosity of solid MgO at high pressures and strain rates measured using the laser-driven Richtmyer-Meshkov instability, Physical Review B 111 (2025) 144108.