IFIBA   22255
INSTITUTO DE FISICA DE BUENOS AIRES
Unidad Ejecutora - UE
artículos
Título:
Ideal evolution of magnetohydrodynamic turbulence when imposing Taylor-Green symmetries
Autor/es:
M.E. BRACHET; M.D. BUSTAMANTE; G. KRSTULOVIC; P. D. MININNI; A. POUQUET; D. ROSENBERG
Revista:
PHYSICAL REVIEW E
Editorial:
AMER PHYSICAL SOC
Referencias:
Lugar: New York; Año: 2013 vol. 87 p. 6632001 - 6632013
ISSN:
1539-3755
Resumen:
We investigate the ideal and incompressible magnetohydrodynamic (MHD)
equations in three space dimensions for the development of potentially
singular structures. The methodology consists in implementing the
fourfold symmetries of the Taylor-Green vortex generalized to MHD,
leading to substantial computer time and memory savings at a given
resolution; we also use a regridding method that allows for
lower-resolution runs at early times, with no loss of spectral accuracy.
One magnetic configuration is examined at an equivalent resolution of
61443 points and three different configurations on grids of 40963
points. At the highest resolution, two different current and vorticity
sheet systems are found to collide, producing two successive
accelerations in the development of small scales. At the latest time, a
convergence of magnetic field lines to the location of maximum current
is probably leading locally to a strong bending and directional
variability of such lines. A novel analytical method, based on sharp
analysis inequalities, is used to assess the validity of the finite-time
singularity scenario. This method allows one to rule out spurious
singularities by evaluating the rate at which the logarithmic decrement
of the analyticity-strip method goes to zero. The result is that the
finite-time singularity scenario cannot be ruled out, and the
singularity time could be somewhere between t=2.33 and t=2.70.
More robust conclusions will require higher resolution runs and
grid-point interpolation measurements of maximum current and vorticity.