Uhm, well, didn't work the way I had planned. Had to wait a moment before posting the close up image. So, again: This piece of great artwork has not been done by me, but by mother nature herself, no art(ificial post)work at all - except for pressing the trigger. Lately, I got some wind tunnel time for playing around with flow visualization, among a few other things, on a (fraction of a) glider wing. Trying to show laminar-turbulent transition and the laminar separation bubble, I always encountered some trouble with turbulent wedges that originated from agglomerated paint. On the pressure side, quite a big turbulent wedge formed near the centre line (flow from the right to the left). When this ran through the laminar separation, the streamlines painted such an amazing picture onto the wall. Looks great, doesn't it? View Birdstrike 00 for an overview of the flow field. Airfoil Eppler E-603 (Twin Astir I), AOA alpha=6°, effective alpha=0°, u=29m/s, Re=2.5E6 low speed wind tunnel (NWK) of TU Dresden flow visualized using soot, oil and kerosene Panasonic Lumix FZ-50