Abstract We focus on simulating the consequences of material interpenetration and mixing arising from perturbations at shocked material interfaces, as vorticity is introduced by the impulsive loading of shock waves, e.g., as in Inertial Confinement Fusion (ICF) capsule implosions. The flow physics is driven by flow instabilities such as Richtmyer-Meshkov, Kelvin-Helmholtz, Rayleigh-Taylor, and vortex stretching; it is capturable with both, classical large-eddy simulation (LES) and implicit LES (ILES) – where small-scale flow dynamics is presumed enslaved to the dynamics of the largest scales. Beyond the complex multiscale resolution issues of shocks and variable density turbulence, we must address the difficult problem of predicting flow transitions promoted by energy deposited at the material interfacial layers during the shock interface interactions. Transition involves unsteady large-scale coherent-structure dynamics resolvable by the coarse grained simulation but not by Reynolds-Averaged Navier-Stokes (RANS) modeling based on equilibrium turbulence assumptions and single-point-closures. We describe a dynamic blended hybrid RANS/LES bridging strategy for applications involving variable-density turbulent mixing applications. We report progress testing implementation of our proposed computational paradigm for relevant canonical problems, in the context of LANL’s xRAGE Eulerian hydrodynamics and BHR unsteady RANS code. Proof-of-concept cases include the Taylor-Green vortex – prototyping transition to turbulence, and a shock tube experiment – prototyping shock-driven turbulent mixing.

中文翻译：

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激波驱动湍流混合粗粒模拟的动态桥接建模

摘要 我们专注于模拟由冲击材料界面处的扰动引起的材料相互渗透和混合的后果，因为涡度是由冲击波的脉冲载荷引入的，例如在惯性约束聚变 (ICF) 胶囊内爆中。流动物理由流动不稳定性驱动，例如 Richtmyer-Meshkov、Kelvin-Helmholtz、Rayleigh-Taylor 和涡旋拉伸；它可以通过经典大涡模拟 (LES) 和隐式 LES (ILES) 来捕获——其中假设小尺度流动动力学受制于最大尺度的动力学。除了冲击和变密度湍流的复杂多尺度分辨率问题之外，我们必须解决预测在激波界面相互作用期间沉积在材料界面层的能量促进的流动转变的难题。过渡涉及不稳定的大规模相干结构动力学，可通过粗粒度模拟解决，但不能通过基于平衡湍流假设和单点闭合的雷诺平均纳维 - 斯托克斯 (RANS) 建模解决。我们描述了一种动态混合混合 RANS/LES 桥接策略，适用于涉及可变密度湍流混合应用的应用。我们在 LANL 的 xRAGE 欧拉流体动力学和 BHR 不稳定 RANS 代码的背景下报告了我们针对相关规范问题提出的计算范式的进度测试实现。概念验证案例包括 Taylor-Green 涡流 – 原型过渡到湍流，