The stability of vortex arrays

The seminal observations by Brown ampersand Roshko (1974) of large scale coherent structures in the turbulent mixing layer have stimulated large amounts of work on the question of the extent to which turbulent flows can be modelled by inviscid laminar dynamics. We wish to know if such modelling can lead to quantitative predictions as well as provide qualitative insights into the mechanisms of the evolution of the turbulent flows. The jury is still out on this question, and more problems have been raised than have been solved, but whatever the final conclusions, there is no doubt that a significant increase in the understanding of vortex dynamics has resulted from the effort. As an aside, it is said that the eye of the artist can see deeper into nature than the trained scientist. The drawings by Leonardo da Vinci of coherent structures and van Gogh's painting open-quotes Starry Nightclose quotes, which resembles closely the pairing process of coherent structures in the mixing layer, illustrate this adage