This study applies the spectral proper orthogonal decomposition (SPOD) to analyze the spatio-temporal characteristics associated with the flow fields of a bubbling fluidized bed. The results suggest there is no singular dominant frequency linked to the highest energy levels; rather, there is a spectrum of frequencies. These frequencies are consistent with the natural frequency from published correlations. SPOD analysis allows for the capture of quasi-periodicity associated with the flow that arises from the semi-periodic evolution of bubbles in the bed and reveals the presence of multiple co-existing spatio-temporal patterns in the particle volume fraction and velocity fields. The dominant SPOD modes can be used for prediction, control, design, optimization, and reduced-order system representation. The capability of a few dominant modes to yield a low-rank reconstruction of the flow fields is demonstrated. The intermittent behavior of the bed is examined through frequency-time analysis of the gas pressure field.

中文翻译：

---

使用谱本征正交分解识别鼓泡气体颗粒流化床中的主要流动结构

本研究应用谱本征正交分解（SPOD）来分析与鼓泡流化床流场相关的时空特征。结果表明，不存在与最高能量水平相关的单一主频率；相反，存在一个频率频谱。这些频率与已发布的相关性中的固有频率一致。 SPOD 分析可以捕获与床中气泡半周期演化产生的流动相关的准周期性，并揭示颗粒体积分数和速度场中存在多种共存的时空模式。主要的 SPOD 模式可用于预测、控制、设计、优化和降阶系统表示。证明了几种主要模式产生流场低阶重建的能力。通过气体压力场的频率-时间分析来检查床的间歇行为。