Small-scale resolving simulations of the turbulent mixing in confined planar jets using one-dimensional turbulence
Small-scale resolving simulations of the turbulent mixing in confined planar jets using one-dimensional turbulence
复制标题
使用一维湍流对受限平面射流中的湍流混合进行小规模解析模拟
DOI：
10.1016/j.ces.2019.04.024
复制
发表时间：
2019
影响因子：
4.7
通讯作者：
H. Schmidt
中科院分区：
文献类型：
--
作者：
M. Klein;Christian Zenker;H. Schmidt
将基于地图的随机一维湍流（ODT）模型应用于受限平面射流，数值研究了湍流混合的小尺度效应。通过将ODT结果与体雷诺数Re= 20，000和40，000的可用参考数据进行比较，对动量输运进行了模型验证。计算各种逐点统计量，并与可用的参考数据进行比较。我们表明，这些数量可以很好地捕捉，或至少在合理的程度上，由独立的模型制定和固定的模型参数。在ODT结果中，只有均方根速度波动仍然被系统地低估（大约为1.5倍）。之后，被动标量的湍流输运解决了施密特数Sc= 1和1250。对于高的施密特数和对比的速度波动，它示出的标量波动方差高达十倍以上的ODT模拟解决巴彻勒尺度。波动方差对于较低的施密特数是显著较小的，但在名义上较高的施密特数下表现出与参考文献更好的一致性。我们认为，这是由于隐式过滤的参考文献中，几乎没有解决柯尔莫哥洛夫规模。ODT湍流谱支持这一解释，因为只有在较高的施密特数下才能观察到类似巴彻勒的标量湍流谱。借助于这些光谱和波动统计，我们得出结论，隐式滤波具有与减少施密特数类似的效果。
Small-scale effects of turbulent mixing are numerically investigated by applying the map-based, stochastic, one-dimensional turbulence (ODT) model to confined planar jets. The model validation is carried out for the momentum transport by comparing ODT results to available reference data for the bulk Reynolds numbers Re= 20, 000 and 40, 000. Various pointwise statistical quantities are computed and compared to the available reference data. We show that these quantities can be captured well, or at least to a reasonable extent, by the stand-alone model formulation and for fixed model parameters. Only the root-mean-square velocity fluctuations remain systematically underestimated in the ODT results (by an approximate factor of 1.5). Afterwards, the turbulent transport of a passive scalar is addressed for the Schmidt numbers Sc= 1 and 1250. For the high Schmidt number and in contrast to the velocity fluctuations, it is shown that the scalar fluctuation variance is up to ten times larger in the ODT simulations resolving the Batchelor scale. The fluctuation variance is notably smaller for the lower Schmidt number, but exhibits better agreement with the references at a nominally higher Schmidt number. We suggest that this is due to implicit filtering in the references, which barely resolve the Kolmogorov scale. ODT turbulence spectra support this interpretation since a Batchelor-like scalar turbulence spectrum is only observed for the higher Schmidt number. With the aid of these spectra and the fluctuation statistics we conclude that implicit filtering has a similar effect as a reduction of the Schmidt number.