On-off intermittency and amplitude-phase synchronization in Keplerian shear flows

Author(s)

Miranda, R. A. ^{[1, 2, 3]} ; Rempel, E. L. ^{[1, 4]} ; Chian, A. C. -L. ^{[1, 4, 5]}

Affiliation

^[1] ITA, BR-12228900 Sao Jose Dos Campos, SP - Brazil

^[2] Inst Phys, Plasma Phys Lab, BR-70910900 Brasilia, DF - Brazil

^[3] Univ Brasilia UnB, Fac UnB Gama, BR-70910900 Brasilia, DF - Brazil

^[4] Natl Inst Space Res INPE, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[5] Univ Adelaide, Sch Math Sci, Adelaide, SA 5005 - Australia

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 448, n. 1, p. 804-813, MAR 21 2015.
• Web of Science Citations: 2

Abstract

We study the development of coherent structures in local simulations of the magnetorotational instability in accretion discs in regimes of on-off intermittency. In a previous paper, we have shown that the laminar and bursty states due to the on-off spatiotemporal intermittency in a one-dimensional model of non-linear waves correspond, respectively, to non-attracting coherent structures with higher and lower degrees of amplitude-phase synchronization. In this paper, we extend these results to a three-dimensional model of magnetized Keplerian shear flows. Keeping the kinetic Reynolds number and the magnetic Prandtl number fixed, we investigate two different intermittent regimes by varying the plasma beta parameter. The first regime is characterized by turbulent patterns interrupted by the recurrent emergence of a large-scale coherent structure known as two-channel flow, where the state of the system can be described by a single Fourier mode. The second regime is dominated by the turbulence with sporadic emergence of coherent structures with shapes that are reminiscent of a perturbed channel flow. By computing the Fourier power and phase spectral entropies in three dimensions, we show that the large-scale coherent structures are characterized by a high degree of amplitude-phase synchronization. (AU)

• FAPESP's process: 13/22314-7 - Magnetic fields and dynamos in space and astrophysical plasmas II
• Grantee: Erico Luiz Rempel
• Support Opportunities: Regular Research Grants
• FAPESP's process: 10/00214-2 - Turbulence and synchronization in astrophysical plasmas
• Grantee: Rodrigo Andres Miranda Cerda
• Support Opportunities: Scholarships in Brazil - Post-Doctoral