论文标题

有条件的时空POD扩展,用于稳定性和预测分析

Conditional space-time POD extensions for stability and prediction analysis

论文作者

Stahl, Spencer, Prasad, Chitrarth, Goparaju, Hemanth, Gaitonde, Datta

论文摘要

相干结构从湍流中的相关性和提取是数据驱动的模态分解技术的主要目标。条件时空适当的正交分解(CPOD)提供了对瞬态动力学的见解,以可自定义的方式揭示了特定流动现象的因果或事件。这项工作利用了降低的子空间中CPOD模式的时间演变,从而导致了新的扩展和适应性,这些扩展和适应超过了其他分解方法的能力。主要是,随后将动态模式分解(DMD)应用于CPOD模式,它为研究了本质上的音调和对流提供了一种灵活的工具。通过扩展CPOD时培来介绍前一种类型,可以表明CPOD-DMD可以精确地重现光谱吊舱模式。关于后者,多分辨率框架(CPOD-MRDMD)产生了精致的“原因和效果”稳定性分析,能够诊断流动中的自然强迫机制以及所得的不稳定模式。在单独的应用程序中,在降低的订单模型的背景下,CPOD属性得到了理解,其中一个实时流量预测了从与CPOD模式相关的活动传感器衍生的极端事件的示例。这项工作中的各种CPOD功能和观点都在以下:非线性混沌洛伦兹系统,超音速边界层过渡中的3D间歇性湍流斑点,未开始的schlieren视频处理,对互动式挂钩造成式挂钩造成式唤醒的造成隔音式的无动物反馈强迫的空气量反馈强迫,以及涉及挂钩的悬赏式涉及唤醒的壁画。

The correlation and extraction of coherent structures from a turbulent flow is a principle objective of data-driven modal decomposition techniques. The Conditional space-time Proper Orthogonal Decomposition (CPOD) offers insight into transient dynamics, revealing the causation of specific flow phenomenon - or events, in a customizable manner. This work exploits the temporal evolution of CPOD modes in a reduced subspace, resulting in new extensions and adaptations that meet or exceed the capabilities of other decomposition methods. Chiefly, it is demonstrated that the subsequent application of dynamic mode decomposition (DMD) to CPOD modes, provides a flexible tool to investigate targeted flow instabilities, both tonal and convective in nature. By extending the CPOD time-horizon to educe the former type, it is shown that CPOD-DMD can exactly reproduce Spectral POD modes. Regarding the latter, a multi-resolution framework (CPOD-mrDMD) yields a refined "cause and effect" stability analysis, capable of diagnosing the natural forcing mechanisms within the flow, and the resulting unstable modes. In a separate application, CPOD properties are appreciated in the context of reduced order models, with an example of real-time flow prediction of extreme events derived from an active sensor correlated to a CPOD mode. The various CPOD functions and perspectives in this work are demonstrated on: the nonlinear chaotic Lorenz system, 3D intermittent turbulent spots in supersonic boundary layer transition, Schlieren video processing of unstarted inlet buzz, the aeroacoustic feedback forcing of a resonating impinging jet, and prediction of intermittent bluff-body wake structures impinging on a channel wall.

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