Coherent structures and secondary motions in open duct flow

This book addresses the turbulence-driven mean secondary motions in straight open duct flow with rectangular cross-section. Despite its weak intensity, the secondary flow influences the primary velocity distribution significantly. Coherent structure analysis showed that the secondary flow is the statistical footprint of quasi-streamwise vortices, and the unique mean flow pattern is a consequence of a vortex sorting mechanism that is only effective in the vicinity of free surface.