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Article Dans Une Revue Il Nuovo cimento della Societa italiana di fisica. C Année : 2019

Numerical simulations of high cross-helicity turbulence from 0.2 to 1 AU

Résumé

Turbulence in the fast stream of the solar wind is maintained despitethe small compressibility and a dominance of outward-propagatingfluctuations ( z^+>z^- , in contrast to its rapid decay in imbalancedhomogenous MHD turbulence. We numerically study if the inhomogeneityintroduced by solar wind expansion can be an effective source of z^-that maintains turbulence. Starting at 0.2 AU with z^-=0 , we obtain adamping with distance of z^+ and a quasi-steady level of z^- . The z^+spectrum steepens with distance toward a -1.4 power-law at 1 AU, whilethe z^- spectrum has a -5/3 power-law index at all distances. Theseproperties are robust against variations of the input spectrum andexpansion rate and are in agreement with in-situ data, suggesting thatimbalanced turbulence can be maintained by expansion alone.
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Dates et versions

hal-03790965 , version 1 (28-09-2022)

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Andrea Verdini, Roland Grappin, Victor Montagud-Camps, Simone Landi, Luca Franci, et al.. Numerical simulations of high cross-helicity turbulence from 0.2 to 1 AU. Il Nuovo cimento della Societa italiana di fisica. C, 2019, 42, pp.17. ⟨10.1393/ncc/i2019-19017-x⟩. ⟨hal-03790965⟩
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