1208 ウェーブレットによる後流乱流の構造の可視化

概要

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Previous studies of the organised motion mostly focused on large-scale structures; investigations of other scales have been relatively scarce since it is difficult to extract the structures of these scales using conventional vortex-detection techniques. In the present investigation, a vector wavelet multi-resolution technique based on a two-dimensional orthogonal wavelet transform was applied to analyzing the velocity data obtained in the turbulent near-wake of a circular cylinder. This technique enables the turbulence structures of various scales to be separated and characterized. The data were simultaneously sampled using eight X-wires in the plane of mean shear. The turbulent flow field was successfully decomposed into the structures of various scales by the vector wavelet multi-resolution technique. The large-scale structures with a central frequency of 109 Hz in the plane of mean shear were consistent with the well-known Karman vortices. The structures that correspond to the saddle region between Karman vortices were identified with the rib-like structures. Both intermediate-scale and small-scale structures exhibit a strong three dimensionality.
社団法人日本機械学会の論文
2002-03-14