It is a matter of principle and a conceptual question

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Unformatted text preview: and other reduced descriptions of turbulence, in particular, as well as in construction of a kind of statistical mechanics of turbulence generally. It is a matter of principle and a conceptual question whether studying turbulence via (some) decompositions is aiding understanding of its fundamental physics. More that one hundred of experience sems to be a clear indication that it is not: I think that the k-space decomposition does actually obscure the physics, MOFFATT, 1990; see also LIEPMANN 1962, TENNKES 1976, and many others. __________________________________________________________ __________________________________________________________ * It is well known that theoretical physics is at present almost helpless in dealing with the problem of strong interactions. LANDAU 1960. The situation in turbulence seems to be not better if not worse . # If we assume as a basic starting point in every theory of turbulence its representation in terms of spectral coefficients, statistical or physical averages, or more generally simple objects conditionally extracted by a weak background, turbulence modelling could be defined reductively, as the art of writing the equations that produce directly such quantities. GERMANO 1999 # Perhaps the biggest fallacy about turbulence is that it can be reliably described (statistically) by a system of equations which is far easier to solve than the full timedependent three-dimensional Navier-Stokes equations BRADSHAW 1994 CONCLUDING CONCLUDING Too little is (still) known about the properties of Too real turbulence. So it seems not justified to put too much (pretty futile) efforts in it’s modeling which mostly is mimicking it without much understanding. Hence the necessity to follow the advice of LEONARDO DA VINCI: Remember, when discoursing about water, to induce first experience, then reason with the emphasis on the physical aspects based in the first place on observations and empirical facts as distinct from intuitive conjectures, hypotheses and ‘models’. The observational aspect is not that trivial as it The involves directly the skill/art/ability to ask the right and correctly posed questions. In our view the first priority should be given to study of basic physical mechanisms of turbulence with the emphasis on qualitative aspects, keeping in mind a somewhat old-fashioned view that curiosity drives better science than `strategies'. This priority includes the study of turbulence itself (per se), rather than multitudes of its models. (per The only exception seems to be the Navier-Stokes equations. A SMALL HOME WORK: WHAT IS WRONG WITH THE PAPER BELOW? THE OR WHY THE ‘RIGHT’ OR RESULT IS FOR THE RESULT WRONG REASON? WRONG...
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This note was uploaded on 09/16/2011 for the course ME 563 taught by Professor Staff during the Spring '11 term at Auburn University.

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