Turbulent Decay and Mixing of Accelerated Inhomogeneous Flows Via a Feature Based Analysis

In this paper, we focus on the late time turbulence of an accelerated inhomogeneous flow environment, a generalization of Richtmyer-Meshkov environment. The numerical investigation is based on two-dimensional (2D) compressible Euler simulation, which is initiated by a shock wave hitting a gas layer (curtain). We observe excellent agreements with the previous decay analysis on 2D viscous isotropic homogeneous turbulence at inertial range[2]. The baroclinic circulation in this environment plays a major role on the mass transport and mixing. The mass transport induced density gradient intensification, in turn, enhances the circulation baroclinically and Zhang, Chen & Zabusky, Journal on Scientific Computing 2 provides the intrinsic forcing at intermediate to high frequency range. With assists of computer graphics based feature extraction and tracking algorithm, we address quantitatively the spatial and temporal diffusivity of the mixing zone. We study and compare both slow/fast/slow (a helium curtain in air) and fast/slow/fast (a air curtain in helium) case to illustrate heuristically the correlation of mass and momentum diffusivity.