Investigation of Richtmyer-Meshkov growth to study material viscosity at high pressures

An accurate understanding of viscosity trends of materials approaching the warm dense matter regime are poorly constrained and yet are important for diverse problems including mantle dynamics of super-Earths. Mantle dynamics drive a wide range of processes that shape terrestrial planets and the viscosity of a planet’s mantle at relevant pressures (>100 GPa) is a critical transport property. A major constituent in the mantle of Earth is MgO and is thus predicted to be prevalent in the mantle of super-Earths. This work focuses on novel experiments to measure the viscosity of MgO at lower mantle conditions. Experiments were performed on OMEGA-EP to measure the growth of a shocked interface. We present preliminary computational results and analysis. We use an in-house finite volume code with AMR and a stiffened equation of state to simulate the Richtmyer-Meshkov instability. We present features of the Richtmyer-Meshkov instability in materials with a stiffened equation of state that deviate from the impulsive model. Lastly, we discuss how the features of our simulations are used in the design and analysis of the experiments.