Meandering motions and their relation to the energy spectrum in turbulent shear flows

• Published in: The International journal of heat and fluid flow 2022-12, Vol.98, p.109064, Article 109064
• Main Authors: Wang, Yu, Tsuji, Yoshiyuki
• Format: Article
• Language: English
• Subjects: Coherent structure; Pre-multiplied spectrum; Velocity decomposition
• ISSN: 0142-727X; 1879-2278
• DOI: 10.1016/j.ijheatfluidflow.2022.109064

This study presents the contribution of the large-scale motions to the turbulent energy using custom-made arrays of hot-wire probes arranged in the span-wise direction. Decomposing the stream-wise velocity fluctuations into large- and small-scale components through the Fourier transform in the span-wise direction and evaluating their scales using the two-point correlation, it is found that the large-scale components have a large contribution in the generation of the outer peak of the turbulent pre-multiplied spectrum (PMS). The outer peak remains even in the low Reynolds number, and it is related to the span-wise organization of large-scale structure of u fluctuations. The spatial correlation in the stream-wise direction shows the large scale of 10δ, where δ is the boundary layer thickness, which is consistent with the outer peak wavenumber of PMS. •Simultaneous measurements were made with a spanwise arrangement of multi-point hot wire probes.•Compared results in channel flow and boundary layer flow.•The characteristics of the large-scale structure at low Reynolds number were investigated.