论文标题
关于局部涡流识别标准在壁构成湍流的压缩表示中的有效性
On the effectiveness of local vortex identification criteria in the compressed representation of wall-bounded turbulence
论文作者
论文摘要
压缩复合物流入涡旋细丝的缠结是涡流表示经典概念的基本含义。已经提出了各种涡旋标识标准，以从可用速度字段中提取涡旋细丝，这是涡流表示实践中的重要过程。这项工作着重于这些识别标准在壁构成湍流的压缩表示中的有效性。考虑了有关涡旋强度的五个局部识别标准和涡旋轴的三个标准。为了促进比较，这项工作首先基于其尺寸和根平方的涡流强度的标准，并使用相应的等效阈值规定。通过试用涡流强度和涡旋轴的识别标准的所有可能组合来讨论涡旋矢量的最佳定义。根据两个原则评估这些标准在压缩表示中的有效性：（1）有效压缩，这意味着所需的信息越少，代表越好； （2）准确的解压缩，这强调了原始速度场可以基于涡流表示，以高精度重建。实际上，在定量上比较了基于这些标准的鉴定涡流轴和涡流等速度的对齐，而解压缩速度场的精度进行了定量比较。使用差别方法描述了对齐度，并通过基于二维场的线性随机估计来实现解压缩过程。这项工作的结果为涡流结合的湍流中的涡流识别标准的应用提供了一些参考。
Compressing complex flows into a tangle of vortex filaments is the basic implication of the classical notion of the vortex representation. Various vortex identification criteria have been proposed to extract the vortex filaments from available velocity fields, which is an essential procedure in the practice of the vortex representation. This work focuses on the effectiveness of those identification criteria in the compressed representation of wall-bounded turbulence. Five local identification criteria regarding the vortex strength and three criteria for the vortex axis are considered. To facilitate the comparisons, this work first non-dimensionalize the criteria of the vortex strength based on their dimensions and root mean squares, with corresponding equivalent thresholds prescribed. The optimal definition for the vortex vector is discussed by trialling all the possible combinations of the identification criteria for the vortex strength and the vortex axis. The effectiveness of those criteria in the compressed representation is evaluated based on two principles: (1) efficient compression, which implies the less information required, the better for the representation; (2) accurate decompression, which stresses that the original velocity fields could be reconstructed based on the vortex representation in high accuracy. In practice, the alignment of the identified vortex axis and vortex isosurface, and the accuracy for decompressed velocity fields based on those criteria are quantitatively compared. The alignment degree is described by using the differential geometry method, and the decompressing process is implemented via the two-dimensional field-based linear stochastic estimation. The results of this work provide some reference for the applications of vortex identification criteria in wall-bounded turbulence.
