Averaged flow fields conditioned to closest Q2-Q4 pairs (Q4s respect to Q2s).
Isosurfaces are 0.7 times the maximum value of the p.d.f. of the points belonging to Q2s (green), Q4s (blue) and vortex clusters (grey),
averaged U=u+Sycg=0 colored by the distance to the vertical center of gravity ycg of the pair and averaged ∂u/∂y=0.115ω' (magenta).
Flow goes into the page. Reλ=100.