Abstract: Modeling and Simulation of RT and RMI Flows with Practical SRS
Modeling and simulation of shock-driven turbulence and materials mixing are challenging due to inherent complex flow physics. These problems include laminar, transitional, and turbulent flow, instabilities, coherent structures, variable density, high and low Mach number regions, and turbulent kinetic energy production by shear and buoyancy mechanisms which are difficult features to model with traditional turbulence models. To address this issue, we have been working on extending the bridging Partially-Averaged Navier-Stokes (PANS) equations to this class of flows. PANS model only resolves the flow scales not amenable to modeling, representing the physics of the remaining scales through a turbulence closure. This strategy unleashes the concept of accuracy-on-demand and is responsible for PANS efficiency (accuracy vs. cost). In this work, we investigate the performance of PANS-LEVM simulating flows driven by the Rayleigh-Taylor (RT) and Richtmyer–Meshkov (RM) instabilities: i) the RT mixing at Atwood number 0.5, and ii) a shock-tube mixing flow. The results confirm that PANS can produce high-fidelity computations of shock-driven turbulence and materials mixing problems. We also analyze the impact of the instabilities and coherent structures driving the flow to the overall accuracy of the simulations to understand the flow physics and the model's performance.