论文标题

可视化和选择动态模式分解组件的不稳定流量

Visualization and Selection of Dynamic Mode Decomposition Components for Unsteady Flow

论文作者

Krake, Tim, Reinhardt, Stefan, Hlawatsch, Marcel, Eberhardt, Bernhard, Weiskopf, Daniel

论文摘要

动态模式分解(DMD)是一种数据驱动且无模型的分解技术。它适用于揭示数值和实验获取数据的时空特征。从概念上讲,DMD将数据对以下组件进行低维光谱分解:称为DMD模式的模式,编码分解的空间贡献,而DMD振幅则指定其影响。每个相关的特征值(称为DMD特征值)都表征了DMD模式的频率和生长速率。在本文中,我们演示了如何利用DMD的组件从时间依赖性流场获取时间和空间信息。我们从DMD的理论背景及其在不稳定流程中的应用开始。接下来,我们使用数学上的DMD检查常规过程,并将其与离散的傅立叶变换相关联。我们的分析表明,当前使用DMD组件的使用有几个缺点。为了解决这些问题,我们调整了组件,并为分解提供了新的和有意义的见解:我们表明我们的改进组件更充分地描述了流量。此外,我们删除了分解中的冗余,并澄清组件之间的相互作用,从而使用户了解组件的影响。这些尊重DMD时空特征的新表示形式,启用了两种聚类方法,将流量分割为物理相关的部分,因此可以用于选择DMD组件。在许多典型的示例中,我们证明了这些技术的组合允许与DMD进行新的见解,以实现不稳定的流程。

Dynamic Mode Decomposition (DMD) is a data-driven and model-free decomposition technique. It is suitable for revealing spatio-temporal features of both numerically and experimentally acquired data. Conceptually, DMD performs a low-dimensional spectral decomposition of the data into the following components: The modes, called DMD modes, encode the spatial contribution of the decomposition, whereas the DMD amplitudes specify their impact. Each associated eigenvalue, referred to as DMD eigenvalue, characterizes the frequency and growth rate of the DMD mode. In this paper, we demonstrate how the components of DMD can be utilized to obtain temporal and spatial information from time-dependent flow fields. We begin with the theoretical background of DMD and its application to unsteady flow. Next, we examine the conventional process with DMD mathematically and put it in relationship to the discrete Fourier transform. Our analysis shows that the current use of DMD components has several drawbacks. To resolve these problems we adjust the components and provide new and meaningful insights into the decomposition: We show that our improved components describe the flow more adequately. Moreover, we remove redundancies in the decomposition and clarify the interplay between components, allowing users to understand the impact of components. These new representations ,which respect the spatio-temporal character of DMD, enable two clustering methods that segment the flow into physically relevant sections and can therefore be used for the selection of DMD components. With a number of typical examples, we demonstrate that the combination of these techniques allow new insights with DMD for unsteady flow.

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