Nonextensivity in turbulence in rotating two-dimensional and three-dimensional flows

✍ Scribed by Charles N Baroud; Harry L Swinney

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 332 KB
• Volume: 184
• Category: Article
• ISSN: 0167-2789
• DOI: 10.1016/s0167-2789(03)00211-2

✦ Synopsis

Our experiments on turbulent flow in a rotating annulus yield probability distribution functions (PDFs) for velocity increments δv( ), where is the separation between points. We fit these PDFs to a form derived for turbulent flows by Beck, who used the Tsallis nonextensive statistical mechanics formalism. For slow rotation rates, we find that the fit parameter q is 1.25 for small . At large , q decreases to unity, the value corresponding to the usual Boltzmann-Gibbs statistics. These results agree with those previously measured in experiments on Couette-Taylor turbulence. However, with rapid rotation of the annulus, the turbulent flow becomes strongly two-dimensional (2D) rather than three-dimensional (3D), and we find q = 1.32 ± 0.04, independent of . This suggests that the coherent structures (vortices), which are a source of intermittency, are important at all length scales in the 2D case.