Abstract Turbulent channel flow was analysed using direct numerical simulations at friction Reynolds numbers Re τ = 180 and 550. The databases were studied using spectral proper orthogonal decomposition (SPOD) to identify dominant near-wall coherent structures, most of which turn out to be streaks and streamwise vortices. Resolvent analysis was used as a theoretical approach to model such structures, as it allows the identification of the optimal forcing and most amplified flow response; the latter may be related to the observed relevant structures obtained by SPOD, especially if the gain between forcing and response is much larger than what is found for suboptimal forcings or if the non-linear forcing is white noise. Results from SPOD and resolvent analysis were compared for several combinations of frequencies and wavenumbers. For both Reynolds numbers, the best agreement between SPOD and resolvent modes was observed for the cases where the lift-up mechanism from resolvent analysis is present, which are also the cases where the optimal resolvent gain is dominant. These results confirm the outcomes in our previous studies ( Abreu et al., 2019 , Abreu et al., 2020 ), where we used a DNS database of a pipe flow for the same Reynolds numbers.

中文翻译：

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湍流通道流中近壁相干结构的解析建模

摘要 使用摩擦雷诺数 Re τ = 180 和 550 时的直接数值模拟分析湍流通道流动。使用光谱适当正交分解 (SPOD) 研究数据库以识别主要的近壁相干结构，其中大部分结果是条纹和流动的漩涡。分辨率分析被用作模拟这种结构的理论方法，因为它允许识别最佳强迫和最放大的流动响应；后者可能与观察到的 SPOD 获得的相关结构有关，特别是如果强迫和响应之间的增益远大于为次优强迫所发现的增益，或者如果非线性强迫是白噪声。比较了频率和波数的几种组合的 SPOD 和解析度分析的结果。对于这两个雷诺数，在存在解析度分析的提升机制的情况下观察到 SPOD 和解析度模式之间的最佳一致性，这也是最佳解析度增益占主导地位的情况。这些结果证实了我们之前的研究（Abreu 等人，2019 年，Abreu 等人，2020 年）中的结果，其中我们使用了管道流的 DNS 数据库以获得相同的雷诺数。