Emergence of very long time fluctuations and 1/f noise in ideal flows

En:

Phys. Rev. E Stat. Nonlinear Soft Matter Phys. 2011;83(6)

Fecha:

2011

Formato:

application/pdf

Tipo de documento:

info:eu-repo/semantics/article
info:ar-repo/semantics/artículo
info:eu-repo/semantics/publishedVersion

Descriptores:

1/F noise -  Amplitude fluctuations -  Different geometry -  Ergodicity -  Fourier space -  Global quantities -  Ideal flow -  Low frequency -  Low resolution

Descripción:

This paper shows the connection between three previously observed but seemingly unrelated phenomena in hydrodynamic (HD) and magnetohydrodynamic (MHD) turbulent flows, involving the emergence of fluctuations occurring on very long time scales: the low-frequency 1/f noise in the power frequency spectrum, the delayed ergodicity of complex valued amplitude fluctuations in wave number space, and the spontaneous flippings or reversals of large-scale fields. Direct numerical simulations of ideal MHD and HD are employed in three space dimensions, at low resolution, for long periods of time, and with high accuracy to study several cases: different geometries, presence of rotation and/or a uniform magnetic field, and different values of the associated conserved global quantities. It is conjectured that the origin of all these long-time phenomena is rooted in the interaction of the longest wavelength fluctuations available to the system, with fluctuations at much smaller scales. The strength of this nonlocal interaction is controlled either by the existence of conserved global quantities with a back-transfer in Fourier space or by the presence of a slow manifold in the dynamics. © 2011 American Physical Society.
Fil:Dmitruk, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Mininni, P.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Identificador(es):

http://hdl.handle.net/20.500.12110/paper_15393755_v83_n6_p_Dmitruk

Derechos:

info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/2.5/ar