Turbulence in Astrophysical and Geophysical Flows
2008; Springer Science+Business Media; Linguagem: Inglês
10.1007/978-3-540-78961-1_4
ISSN1616-6361
Autores Tópico(s)Climate variability and models
ResumoTurbulence is a physical process that enjoys some unique characteristics, first among which is the fact that it is among the most ubiquitous phenomena in the physical world and yet is one of the least understood physical processes. Let us just consider that all existing stars (the number of which is around ∼ 10, not far from the Avogadro’s number) use or have used turbulence during different phases of their lifetime. The atmosphere of the earth, a habitat in which we spend all our life, is regularly turbulent and so are the oceans. Much to the surprise of anyone who begins to study the subject, one finds that the most skillful practitioners at “taming” turbulence are aerospace engineers who try to minimize the unsettling effects of air turbulence on the commonly shared assumption that a smooth flight is more exciting than a bumpy one. But to advance their skills, engineers could hardly afford waiting for a theory of turbulence to be developed and tested. Wind tunnels provide much of the needed help for the effects of a turbulent flow on the wings of an aeroplane which can be examined in detail using repeated experiments. This leads to quite a satisfactory “description” of turbulence, but that is not sufficient to build a theory. For example, the huge wealth of spectroscopy data on absorption and emission properties of gases found a simple, logical explanation only when the atomic theory was invented and disparate results were explained by a set of few simple rules. There is not yet an equivalent in the field of turbulence which among other vicissitudes, is also struggling to find a proper place in science: it straddles mathematics, physics, engineering, geophysics and astrophysics. Apocryphal stories tell that W. Heisenberg, one of the founders of quantum mechanics, who pioneered with N. Kolmogorov the concept of turbulent viscosity, wanted to ask God what turbulence was all about, not the structure of quarks, not the true mass of neutrinos, not the unification of general relativity and quantum mechanics, not the reality of strings, but turbulence. More historically certain is the assertion by another great scientist, R.P. Feynman, that turbulence remains the biggest unsolved
Referência(s)