Numerical investigation of turbulence in reshocked Richtmyer–Meshkov unstable curtain of dense gas

Abstract

When a shock wave impacts an interface between two fluids, the misalignment of the pressure and density gradients results in deposition of baroclinic vorticity on the interface. This leads to the growth of initial perturbations on the interface causing the phenomenon of Richtmyer-Meshkov instability (RMI) [1]. The RMI produces turbulent mixing of the fluids which plays an important role in many physical and technological processes like inertial confinement fusion, supersonic combustion, and impact dynamics of liquids. The RMI is also believed to be the reason for the increased mixing observed in the optical output of supernova 1987A. Understanding this process requires robust numerical algorithms capable of simulating this highly non-linear flow and high quality repeatble experimental data to validate the numerical findings. Experimental limitations (difficulty generating a well characterized initial interface between two fluids, and diagonostic limitations) and shortcomings of numerical algorithms have constrained detailed explorations of the physics of this intability. Recent improvements in experimental methods (like membrane-less techniques to generate an interface) have provided reliable data for numerical code validation and simulation of this flow to characterize the turbulent mixing between the fluids. In this work one such configuration of a shock in air impacting a curtain of cylinders of dense gas is chosen for numerical simulation. The results are compared to available experimental data [2] and some turbulence statistics are reported.