Predicting the response of small-scale near-wall turbulence to large-scale outer motions
Predicting the response of small-scale near-wall turbulence to large-scale outer motions
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DOI：
10.1063/1.4939712
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发表时间：
2016-01-01
影响因子：
4.6
通讯作者：
Leschziner, Michael
中科院分区：
文献类型：
--
作者：
Agostini, Lionel;Leschziner, Michael
提供了一个唯象模型，基于后处理直接数值模拟（DNS）数据在Re τ = 1020，它允许近壁湍流统计预测从一个“通用信号”，不受大规模运动的影响，结合信息的大规模运动在外部对数律区域。大尺度和小尺度运动的分离，不寻常的是，通过“经验模式分解”的方法，没有明确的波长截止。该模型首先产生的通用字段通过删除，从一个全体积的湍流场在任意的时间水平，大规模的对流位移（足迹），调制的小规模的运动，所造成的大规模的运动，和扭曲所产生的扫描诱导飞溅的影响。与其他建模工作相比，本框架扩展到所有三个速度分量，如联合（u-v）和（u-w）概率密度函数（PDF）所示。然后，该模型成功地用于重建完整的近壁统计相结合的通用字段与外部大规模的运动在任何时间水平以外的通用字段被确定。(C)2016 AIP Publishing LLC.
A phenomenological model is provided, based on post-processing Direct Numerical Simulation (DNS) data at Re-tau = 1020, which permits the near-wall-turbulence statistics to be predicted from a "universal signal," free from the effects of large-scale motions, in combination with information on the large-scale motions in the outer log-law region. The separation of large-scale and small-scale motions is effected, unusually, by means of the "Empirical Mode Decomposition" method, without explicit wavelength cutoffs. The model first yields the universal field by removing, from a full-volume turbulence field at an arbitrary time level, the effects of large-scale convective displacements (footprints), the modulation of the small-scale motions, caused by the large-scale motions, and distortions arising from sweep-induced splatting. In contrast to other modelling efforts, the present framework extends to all three velocity components, as is demonstrated by reference to joint (u-v) and (u-w) probability-density functions (PDFs). The model is then successfully used to reconstitute the full near-wall statistics by combining the universal field with the outer large-scale motions at any time level other than that for which the universal field was determined. (C) 2016 AIP Publishing LLC.