Bob Johnson wrote:
Well, Google has heard of it, so it must be real. Dr. Jack could comment
on it, but I'll wager we wouldn't be any smarter.

I hadn't heard of "pancake" turbulence, but since you posted the link I
checked it out and although I've never seen a "Lumley diagram" before my
interpretation is the following. "Turbulence" is a rapid fluctuation in
velocity, and those velocity fluctuation can be in any of 3 directions
(1 vertical, 2 horizontal). In "pancake turbulence" the velocity
fluctuations in the vertical direction are much smaller in magnitude
than the velocity fluctuations in the horizontal direction. (In
"isotropic" turbulence, which might also be called "fully developed
turbulence", the velocity fluctuations are of equal magnitude in all
three directions.) Don't know if that makes you any smarter or not!

DrJack