Constant-energetics control-based forcing methods in isotropic helical turbulence

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Takuya Kitamura
Keyword(s):  
Helical Turbulence

scholarly journals Compressible helical turbulence: Fastened-structure geometry and statistics

2021 ◽  
Vol 28 (3) ◽  
pp. 032302
Author(s):  
Jian-Zhou Zhu
Keyword(s):  
Helical Turbulence ◽  
Structure Geometry

On the problem of magnetic field generation by helical turbulence

1995 ◽  
Vol 81 (1-2) ◽  
pp. 101-112 ◽  
Author(s):  
M. V. Kurgansky
Keyword(s):  
Magnetic Field ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Helical Turbulence

Oscillatory mean-field dynamos with a spherically symmetric, isotropic helical turbulence parameterα

2003 ◽  
Vol 67 (2) ◽  
Author(s):  
Frank Stefani ◽  
Gunter Gerbeth
Keyword(s):  
Mean Field ◽  
Spherically Symmetric ◽  
Helical Turbulence

scholarly journals Polarized Cosmological Gravitational Waves from Primordial Helical Turbulence

2005 ◽  
Vol 95 (15) ◽  
Author(s):  
Tina Kahniashvili ◽  
Grigol Gogoberidze ◽  
Bharat Ratra
Keyword(s):  
Gravitational Waves ◽  
Helical Turbulence

Lagrangian velocity covariance in helical turbulence

1977 ◽  
Vol 81 (2) ◽  
pp. 385-398 ◽  
Author(s):  
Robert H. Kraichnan
Keyword(s):  
Correlation Time ◽  
Perturbation Expansion ◽  
Direct Interaction ◽  
Helical Turbulence ◽  
Quantitative Accuracy ◽  
Lagrangian Velocity ◽  
Thin Spherical Shell ◽  
Direct Interaction Approximation ◽  
Interaction Approximation ◽  
Substantial Factor

The effect of helicity on the Lagrangian velocity covarianceUL(t) in isotropic, normally distributed turbulence is examined by computer simulation and by a renormalized perturbation expansion forUL(t). The first term of the latter represents Corrsin's (1959) conjecture (extrapolated to allt), which relatesUL(t) to the Eulerian covariance and the distributionG(x, t) of fluid-element displacement. Truncation of the expansion at the first term yields the direct-interaction approximation forG(x, t). The expansion suggests that with or without helicity Corrsin's conjecture is valid ast→ ∞ and that in either caseUL(t) behaves asymptotically like$t^{-(r+\frac{3}{2})}$if the spectrum of the Eulerian field varies likekr+2at small wavenumbers. Corrsin's conjecture breaks down at small and moderatetif there is strong helicity while remaining accurate at alltin the mirror-symmetric case. Computer simulations for a frozen Eulerian field with spectrum confined to a thin spherical shell inkspace indicate that strong helicity induces an increase in the Lagrangian correlation time by a factor of approximately three. Direct-interaction equations are constructed for the Lagrangian space-time covariance and the resulting prediction forUL(t) is compared with the simulations. The effect of helicity is well represented quantitatively by the direct-interaction equations for small and moderatetbut not for larget. These frozen-field results imply good quantitative accuracy at alltin time-varying turbulence whose Eulerian correlation time is of the order of the eddy-circulation time. In turbulence with weak helicity, the directinteraction equations imply that the Lagrangian correlation of vorticity with initial velocity is more persistent thanUL(t), by a substantial factor.

scholarly journals Inverse cascade of energy in helical turbulence

2020 ◽  
Vol 895 ◽  
Author(s):  
Franck Plunian ◽  
Andrei Teimurazov ◽  
Rodion Stepanov ◽  
Mahendra Kumar Verma
Keyword(s):  
Inverse Cascade ◽  
Helical Turbulence ◽  
Image Position

Dynamo action in rotating convection

2009 ◽  
Vol 5 (H15) ◽  
pp. 347-347
Author(s):  
Gustavo Guerrero ◽  
Elisabete M. de Gouveia Dal Pino
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Hydrostatic Equilibrium ◽  
Computational Domain ◽  
Dynamo Action ◽  
Rotating Convection ◽  
Helical Turbulence ◽  
Large Scale Magnetic Field ◽  
Unstable Layer ◽  
Scale Shear

AbstractWe present MHD numerical simulations of a rotating turbulent convection system in a 3D domain (we have used the finite volume, Goudunov type MHD code PLUTO (Mignone et al. 2007)). Rotating convection is the natural scenario for the study of the dynamo action which is able to generate a large scale magnetic field, like the observed in the sun. Though we have neglected in the present approach the Ω effect, due to a large scale shear, our model is appropriate to test the controversial existence of the so called α effect that arises from helical turbulence (e.g. Cattaneo & Hughes 2006, Käpylä et al. 2009). We start with a two-layer piece-wise polytropic region in hydrostatic equilibrium (e.g. Ziegler 2002), considering one stable overshoot layer at the bottom and a convectively unstable layer at the top of the computational domain. We have allowed this hydrodynamic system to evolve up to the steady state, i.e., after about 10 turnover times (τ). Then, we introduced a seed magnetic field and let the system evolve for more ~40 τ. Our preliminary results are summarized below in Figure 2.

scholarly journals Dynamo effect in decaying helical turbulence

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Axel Brandenburg ◽  
Tina Kahniashvili ◽  
Sayan Mandal ◽  
Alberto Roper Pol ◽  
Alexander G. Tevzadze ◽  
...  
Keyword(s):  
Helical Turbulence ◽  
Dynamo Effect

Electrohydrodynamic (EHD) vortices in helical turbulence

1996 ◽  
Vol T63 ◽  
pp. 91-98 ◽  
Author(s):  
Hiroshi Kikuchi
Keyword(s):  
Helical Turbulence
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