I have been puzzling again as to whether my surmise that there must be two roughly parallel diagonal standing shockwaves on the 737NG inboard section can be true.
So I have been revisiting those links that Brian so very kindly provided earlier in the thread, including that brilliant 'fish in the river' illustration.
There is the possibility that what I have seen is some kind of break in the standing shockwave that occurs exactly at the chord where the power unit is mounted i.e. that the somehow the presence of the engine stuck right out in front at that point somehow accelerates the outboard air more than the inboard air that goes around it. That doesn't sit too well in my mind.
I can however imagine that there might be a contact lens type shockwave around the front of power unit, out ahead of the wing, on the basis that the engine cannot possibly 'eat' all the air it confronts even at 39000 where I was sat watching it.
And further to that idea I can then imagine that near the engine, there might be two 'funnels' of fast air resulting which the wing then encounters and causes to go supersonic over the top:
1. inboard between power unit and fuselage
2. outboard but quickly tucking in diagonally towards the fuselage.
Maybe I should try to draw it, scan it and photobucket what I mean, or am I letting my imagination run too far already?
PS Brian, have you seen that Blue Angels video on YouTube?
http://www.youtube.com/watch?v=K7rAUu8djZ4