My PhD is in transitional flows, in particular the transition from laminar to turbulent boundary layers under elevated freestream turbulence — so flows like tha

My PhD is in transitional flows, in particular the transition from laminar to turbulent boundary layers under elevated freestream turbulence — so flows like that over the roof of your car, but you also see them on gas turbine blades as well as subsonic aircraft wings. We typically refer to these puffs as turbulent spots. They manifest in many ways. Lots of researchers generate them artificially with a wall disturbance however they can occur all by themselves. A boundary layer velocity profile can become unstable vis T-S waves [0] and via a complex mechanism generate turbulent spots. They grow spatially until the boundary layer is saturated. On the other hand freestream turbulence can buffer the outer part of the boundary layer resulting in a streaky flow near the wall. These streaks can interact locally and generate spots of their own bypassing the T-S process entirely. However after the onset the growth of spots to saturate the boundary layer is remarkably similar. You can download an enormous DNS database of just a single flow case here if you like. [1] [0] https://en.m.wikipedia.org/wiki/Tollmien–Schlichting_wave https://en.m.wikipedia.org/wiki/Tollmien–Schlichting_wave [1] http://turbulence.pha.jhu.edu/Transition_bl.aspx http://turbulence.pha.jhu.edu/Transition_bl.aspx