Turbulent heat transfer in a square duct, where a finite section of a single duct boundary is heated with an infinitely thin foil, was analyzed with LES and DNS approaches. Both computations were performed with OpenFOAM code with passive scalar approximation, using second order accurate schemes. Results are obtained for the key velocity and temperature statistics in the duct, with an emphasis on the temperature profiles and temperature fluctuations at the foil boundary, which appear due to the imposed constant heat flux boundary condition at the foil. Comparison of DNS and standard LES-WALE model show 20% higher foil temperatures and temperature fluctuations in LES results. These differences are explained with detailed analysis of the LES-WALE model near-wall behavior. It has been demonstrated that LES-WALE yields highly accurate results only when employed with a finely resolved mesh. However, the computational costs associated with such refinement may not be necessarily justified especially with respect to DNS.

中文翻译：

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DNS 与 LES：带加热箔边界的方形管道中的湍流

使用 LES 和 DNS 方法分析了方形管道中的湍流传热，其中单个管道边界的有限部分由无限薄的箔片加热。这两种计算都是使用 OpenFOAM 代码和被动标量近似，使用二阶精确方案来执行的。获得了管道中关键速度和温度统计数据的结果，重点是箔边界处的温度分布和温度波动，这是由于箔处施加的恒定热通量边界条件而出现的。 DNS 和标准 LES-WALE 模型的比较显示 LES 结果中的箔温度和温度波动高出 20%。这些差异可以通过 LES-WALE 模型近壁行为的详细分析来解释。事实证明，只有与精细解析的网格一起使用时，LES-WALE 才能产生高度准确的结果。然而，与这种细化相关的计算成本可能不一定合理，尤其是对于 DNS 而言。