Combined simultaneous flow visualization of dye-streak pattern/particle-pass line in the near-wall turbulence

Correlation between simultaneous visual pattern of coherent motion and fluctuating components of velocity in the near-wall turbulent flow is investigated using ‘dyeparticle-image velocimetry’ technique. The results indicate that the dye-streak pattern of coherent motion associates with the transversal vortical structure in the head of wall streamwise vortices', large-scale sweep event and large-scale ejection event. DPIV technique plays an important role to understand the physics of coherent motionin the near-wall turbulence.