Abstract The accuracy of Reynolds-averaged Navier-Stokes results for turbulent scalar transport are affected by epistemic uncertainty in the Reynolds stress model in two ways: by altering the mean velocity field that advects the scalar, and by altering the inputs required for scalar flux models. We investigate these effects by propagating uncertainty in the Reynolds stress model to the prediction of scalar quantities in simulations of a pin-fin heat exchanger. The Reynolds stress model uncertainty is quantified by perturbing the anisotropy of the predicted stress tensor towards the three limiting realizable states. This uncertainty is then propagated to the scalar turbulence transport via the conservation law for the mean scalar and the turbulent scalar flux model. We consider three different scalar flux models that explicitly take the Reynolds stresses as input, and evaluate the performance of the models by verifying if high-fidelity large eddy simulation results are encompassed by the model predictions. The results indicate that the predicted uncertainty depends on both the general level of momentum transport and the most-relevant stress component, which is affected by the anisotropy perturbations. The predictions provide a similar bounding behavior for the overall temperature field as for the momentum field, but fail in bounding the local heat transfer rates in several locations. The bounding behaviors are further analyzed in terms of the predicted uncertainty in the flux magnitude, direction, and divergence to identify opportunities for further improvement of the proposed methods.

中文翻译：

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在针鳍阵列的雷诺平均 Navier-Stokes 模拟中量化湍流模型的不确定性。第 2 部分：标量传输

摘要 湍流标量输运的雷诺平均 Navier-Stokes 结果的准确性受雷诺应力模型中认知不确定性的影响有两种方式：通过改变平流标量的平均速度场，以及通过改变标量通量模型所需的输入. 我们通过将雷诺应力模型中的不确定性传播到针翅式换热器模拟中的标量预测来研究这些影响。雷诺应力模型的不确定性通过将预测应力张量的各向异性扰动到三个极限可实现状态来量化。这种不确定性然后通过平均标量和湍流标量通量模型的守恒定律传播到标量湍流传输。我们考虑了三种不同的标量通量模型，这些模型明确地将雷诺应力作为输入，并通过验证模型预测是否包含高保真大涡模拟结果来评估模型的性能。结果表明，预测的不确定性取决于动量传输的一般水平和最相关的应力分量，后者受各向异性扰动的影响。这些预测为整体温度场提供了与动量场类似的边界行为，但未能在几个位置对局部传热速率进行边界处理。根据通量大小、方向和散度的预测不确定性进一步分析边界行为，以确定进一步改进所提出方法的机会。并通过验证模型预测是否包含高保真大涡模拟结果来评估模型的性能。结果表明，预测的不确定性取决于动量传输的一般水平和最相关的应力分量，后者受各向异性扰动的影响。这些预测为整体温度场提供了与动量场类似的边界行为，但未能在几个位置对局部传热速率进行边界处理。根据通量大小、方向和散度的预测不确定性进一步分析边界行为，以确定进一步改进所提出方法的机会。并通过验证模型预测是否包含高保真大涡模拟结果来评估模型的性能。结果表明，预测的不确定性取决于动量传输的一般水平和最相关的应力分量，后者受各向异性扰动的影响。这些预测为整体温度场提供了与动量场类似的边界行为，但未能在几个位置对局部传热速率进行边界处理。根据通量大小、方向和散度的预测不确定性进一步分析边界行为，以确定进一步改进所提出方法的机会。