Coherent structures over riblets in turbulent boundary layer studied by combining time-resolved particle image velocimetry (TRPIV), proper orthogonal decomposition (POD), and finite-time Lyapunov exponent (FTLE)

Li Shan¹, Jiang Nan^{1, †}, Yang Shaoqiong^{1, ‡}, Huang Yongxiang², Wu Yanhua³

(a) Robinson’s summary of structures found in the direct numerical simulation of wall turbulence;^[18] (b) Hairpin-packet paradigm by Adrian et al.^[19]