The separated turbulent flow past a square cylinder mounted centrally inside a plane channel has been numerically investigated in this work. A three-dimensional paradigmatic calculation was carried out to capture the essence of flow parameters through different detached-eddy simulations (DESs). The predictions were performed based on the original DES, delayed DES, and one modified DES (MDES). First, MDES closure was validated by comparing the simulation results with the experimental data of separated flow through a U-turn duct, thereafter commencing the predictions of the flow past a square cylinder. The comparisons between the numerical and available experimental results show that the MDES has better capability than the DES to capture the characteristics of global variables including the Strouhal number, mean drag and lift coefficients, and their standard deviations for the square cylinder case. Furthermore, a detailed quantitative comparison in terms of the time-averaged velocity profiles at specified locations reveals that MDES could be more reasonable and has better fidelity than the other two models. A good match among the contours of eddy viscosity, Q-criterion, and turbulent kinetic energy shows that MDES has correctly reproduced the turbulent production in the wake flow. The main significance of this study is that it demonstrates the potential of a modified DES closure to investigate the unsteady dynamics in the wake flow past a square cylinder and expected to make sense for other wake flows of engineering interest.

中文翻译：

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改进的绕过方形圆柱体的非定常湍流的分离涡模拟

在这项工作中，通过数值研究了通过安装在平面通道中央的方形圆柱体的分离湍流。进行了三维范式计算，以通过不同的分离涡流模拟（DES）捕获流量参数的本质。该预测是基于原始DES，延迟DES和一个修改后的DES（MDES）进行的。首先，通过将模拟结果与通过U形弯管的分离流的实验数据进行比较，验证了MDES的封闭性，然后开始了对通过方形圆柱体的流的预测。数值和可用实验结果之间的比较表明，MDES比DES具有更好的能力来捕获包括Strouhal数，平均阻力和升力系数以及它们在方柱情况下的标准偏差在内的全局变量的特征。此外，在指定位置的时间平均速度曲线方面进行的详细定量比较显示，MDES可能比其他两个模型更合理且保真度更高。涡流粘度Q值之间的良好匹配判据和湍动能表明，MDES正确地再现了尾流中的湍流产生。这项研究的主要意义在于，它证明了改进的DES封闭装置可用于研究流经方筒的尾流中的非稳态动力学，并有望对其他工程感兴趣的尾流有意义。