Application of vortex identification schemes to direct numerical simulation data of a transitional boundary layer

We have demonstrated how various vortex identification and visualization criteria perform using direct numerical simulation data from a transitional and turbulent boundary layer by Sayadi, Hamman, and Moin [“Direct numerical simulation of complete transition to turbulence via h-type and k-type secondary instabilities,” Technical Report, Stanford University, CTR Annual Research Briefs, 2011]. The presence of well-known Λ vortices in the transitional region provides a well defined and yet realistic benchmark for evaluation of various criteria. We investigate the impact of changing the threshold used for iso-surface plotting.