乱流境界層における大規模渦構造とバースト現象の関連性に関する実験的研究(<小特集>局時化した流動の法則と機能)

概要

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The relationships between large-scale bulge and valley structures and bursting phenomena in a turbulent boundary layer with zero pressure gradient are investigated by means of laboratory experiments using a wind tunnel. To investigate the spatio-temporal development of coherent structures in the turbulent boundary layer, simultaneous measurements of wall static pressure and multi-point streamwise velocities were carried out using a microphone pressure sensor and a rake of 23 I-type hot wires enable to cover the whole region of the" boundary layer. The KL expansion was applied to the measured velocity signals. The velocity field was reconstructed by either low-order or higher-order modes to investigate the coherent structures of the velocity field. The bursting events were detected by the VITA method. The bulge and valley structures were also detected by an original conditional sampling method. The results show that, at low-mode, only the large-scale weak vortex structure rotating against the mean shear stress accompanies the bursting event. At higher-mode, large-scale vortices are found to be poorly related to the bursting motions.
一般社団法人日本機械学会の論文
2007-03-25