2012/01/17 by J. D. Szezech Jr, I. L. Caldas, S. R. Lopes +2 · 1 citation
Physics and Astronomy · #nlin.CD
paper · pdf · doi:10.1103/physreve.86.036206
20 pages, 9 figures
arxiv created 2012/01/17 · arxiv updated 2015/06/03
In fluids and plasmas with zonal flow reversed shear, a peculiar kind of transport barrier appears in the shearless region, one that is associated with a proper route of transition to chaos. Using a symplectic nontwist maps, which model such zonal flows, we investigate these barriers. In particular, the standard nontwist map, a paradigm of nontwist systems, is used to analyze the parameter dependence of the transport through a broken shearless barrier. Varying a proper control parameter, we identify the onset of structures with high stickiness that give rise to an effective barrier near the broken shearless curve. Several diagnostics are used: stickiness is measured by escape time and transmissivity plots, while barriers that separate different regions of stickiness are identified by employing two indicators in the phase space, the finite-time rotation number and the finite-time Lyapunov exponent.