Properties of synthetic and natural streamwise vortex pairs in the near-wall region of turbulent boundary layers

Abstract

A low-friction-Reynolds-number (Reτ≈400-480) turbulent boundary layer perturbed by additional streamwise vortices is investigated using wall-resolved large-eddy simulation. To better understand how one might passively mimic and/or manipulate the formation of streamwise vortex pairs (SVPs) that naturally occur as part of the near-wall cycle, SVPs are artificially produced by small vortex generators (of height h+=30) within the near-wall region. Thus, the present study contrasts the more typical large vortex generators used in turbulent boundary layer manipulation and separation control. Analyses employing a triple decomposition of velocity and pressure and its extension to the incompressible ..