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首页> 外文会议>AIAA SciTech forum and exposition >A Novel Strategy to Identify Dynamically Dominant Inter-Scale Couplings for Application to Large-Eddy Simulation of Premixed Turbulent Combustion
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A Novel Strategy to Identify Dynamically Dominant Inter-Scale Couplings for Application to Large-Eddy Simulation of Premixed Turbulent Combustion

机译：识别动态主导尺度间耦合的新策略，用于预混湍流燃烧大涡模拟

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Large-Eddy Simulation (LES) is a powerful formulation for model turbulent reacting flows that balances lower resolution with predictions of variance dominant momentum and energy fluctuations. Central to the LES framework is the need to model nonlinear interactions between the variance-dominant resolved-scale (RS) motions and subfilter-scale (SFS) fluctuations. A central feature of premixed turbulent combustion is nonlinear flame-turbulence interactions, a key element that involves advective nonlinear coupling between velocity and momentum, energy and species concentration. In this work, we extract the dominant RS-SFS advective nonlinear interactions to isolate SFS content that underlies the evolution of the resolved scales for encapsulation within mathematical forms for potential use in advanced modeling strategies. We take advantage of the mathematical simplicity of the Fourier spectral description of the equations of motion where advective nonlinearities are given by a sum of "triadic" interactions each of which involves three Fourier modes whose wave-vectors form a triangle in multidimensional Fourier space. This elemental representation of key nonlinearities is used to develop a novel strategy to arrange and down-select the dominant nonlinear RS-SFS couplings underlying the evolution of RS motions, and extract the corresponding SFS content associated with dynamically dominant RS-SFS dynamics. The procedure is applied to analysis of "reduced physics" simulations of flame-vortex interactions with a new method for analysis of non-periodic signals in multi-dimensional Fourier-space. For primary variables with dominant variane in the grid-resolved scales and fast decay of energy into the subfllter scales, the resolved-scale features of the dynamically dominant SFS content are shown to be coupled with the smaller resolved scales characterizing the corrugations and thickness of the RS flame front. In contrast, the dynamically dominant SFS content of intermediate species involved in heat release extend farther in Fourier space to smaller scales. These SFS fluctuations are shown to follow the smallest flame-front corrugations, which deviate from the RS flame geometry in regions with high curvature, such as the flame cusps. The results of this study provide insights relevant to advanced modeling strategies designed to capture key RS-SFS couplings into prediction of RS dynamics.
机译：大涡模拟（LES）是用于模型湍流反应流的强大公式，它使较低的分辨率与方差占主导地位的动量和能量波动的预测保持平衡。 LES框架的核心是需要对方差支配的分辨尺度（RS）运动与子滤波器尺度（SFS）波动之间的非线性相互作用进行建模。预混湍流燃烧的主要特征是非线性火焰-湍流相互作用，这是涉及速度与动量，能量和物质浓度之间对流非线性耦合的关键因素。在这项工作中，我们提取了主要的RS-SFS平流非线性相互作用，以隔离SFS内容，这是用于数学形式内封装的可分辨尺度演化的基础，可在高级建模策略中使用。我们利用运动方程的傅立叶频谱描述的数学简单性，对流非线性是由“三重”相互作用的总和给出的，每个对流非线性都涉及三个傅立叶模式，其波矢量在多维傅立叶空间中形成三角形。关键非线性的这种基本表示用于开发一种新颖的策略，以安排和向下选择基于RS运动演变的主要非线性RS-SFS耦合，并提取与动态主要RS-SFS动力学相关的相应SFS内容。该程序通过一种用于分析多维傅立叶空间中非周期性信号的新方法，用于分析火焰-涡旋相互作用的“简化物理学”模拟。对于在网格分辨尺度上具有显性天体的主变量和能量快速衰减到亚滤尺度中，动态显性SFS含量的分辨尺度特征与较小的分辨尺度（表征波纹和厚度）相关联。 RS火焰前。相反，涉及热释放的中间物质的动态占主导地位的SFS含量在傅立叶空间中延伸到更小尺度。这些SFS波动显示为遵循最小的火焰前波纹，该波纹在高曲率区域（例如火焰尖峰）中偏离RS火焰几何形状。这项研究的结果提供了与高级建模策略相关的见解，这些策略旨在将关键的RS-SFS耦合捕获到RS动力学的预测中。

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