Verdini, A. and Grappin, R. and Montagud-Camps, V. and Landi, S. and Franci, L. and Papini, E. (2019) Numerical simulations of high cross-helicity turbulence from 0.2 to 1 AU. Il nuovo cimento C, 42 (1). pp. 1-5. ISSN 1826-9885
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Abstract
Turbulence in the fast stream of the solar wind is maintained despite the small compressibility and a dominance of outward-propagating fluctuations (z+ >z −), in contrast to its rapid decay in imbalanced homogenous MHD turbulence. We numerically study if the inhomogeneity introduced by solar wind expansion can be an effective source of z− that maintains turbulence. Starting at 0.2 AU with z− = 0, we obtain a damping with distance of z+ and a quasi-steady level of z−. Thez+ spectrum steepens with distance toward a −1.4 power-law at 1 AU, while the z− spectrum has a −5/3 power-law index at all distances. These properties are robust against variations of the input spectrum and expansion rate and are in agreement with in-situ data, suggesting that imbalanced turbulence can be maintained by expansion alone.
| Item Type: | Article |
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| Subjects: | 500 Scienze naturali e Matematica > 530 Fisica |
| Depositing User: | Marina Spanti |
| Date Deposited: | 27 Nov 2020 09:57 |
| Last Modified: | 27 Nov 2020 09:57 |
| URI: | http://eprints.bice.rm.cnr.it/id/eprint/20382 |
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