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

POD energy distribution: (a) fractional contribution of each POD mode to the total energy; (b) cumulative energy distribution.