Genesis and dynamics of coherent structures in near-wall turbulence: a new look

Using direct numerical simulations of turbulent channel flow, some new insights into the regeneration and dynamics of near-wall longitudinal vortices are given. In particular, the statistically dominant coherent structures (CS) are educed through ensemble averaging of the entire 3D extent of individual structures mature vortices. The CS are elongated quasi-streamwise vortices that act to sustain the preexisting streak. A new spatiotemporal regeneration mechanism is developed. This regeneration mechanism is distinct from those proposed previously and suggests new strategies for feasible, large-scale control of drag.