@Owain Glyndwr,
Thank you for the excellent Arvel E. Gentry document. That can be taught to begin. The most of the false theories are well explained. In his document "streamlines" may be considered as a good pedagogic tool.
My question about "streamline" is still a little deeper : where do you put the turbulence in the unhomogeneous "streamline" ? David Ruelle and Floris Taken (Institut des Hautes Etudes Scientifiques, Bures sur Yvette (France)) showed (1) that turbulence in his phases space has an strange attractor which is of length infinite in the area, and then it is a fractale.
Jerry P. Gollub and Harry L. Swinney showed by experimenting on the Couette-Taylor (2) flux that Lev D. Landau's theory of turbulence was wrong, and they discovered only very few transitions in increasing the speed, and chaos appeared very quickly.
roulishollandais
(1) "On the nature of turbulence" Communications in Mathematical Physics, n°23, 1971,pp.155-183
(2) "Onset of turbulence in a Rotating Fluid" Physical Review Letters n°35, 1975, p.927