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arXiv · 1609.00598

Scaling of compressible magnetohydrodynamic turbulence in the fast solar wind

Supratik Banerjee·Lina Z. Hadid·Fouad Sahraoui·Sebastien Galtier
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Abstract

The role of compressible fluctuations in the energy cascade of fast solar wind turbulence is studied using a reduced form of an exact law derived recently (Banerjee and Galtier, PRE, 2013) for compressible isothermal magnetohydrodynamics and in-situ observations from the THEMIS B/ARTEMIS P1 spacecraft. A statistical survey of the data revealed a turbulent energy cascade over two decades of scales, which is broader than the previous estimates made from an exact incompressible law. A term-by-term analysis of the compressible model reveals new insight into the role played by the compressible fluctuations in the energy cascade. The compressible fluctuations are shown to amplify (2 to 4 times) the turbulent cascade rate with respect to the incompressible model in 10 % of the analyzed samples. This new estimated cascade rate is shown to provide the adequate energy dissipation required.

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Supratik Banerjee, Lina Z. Hadid, Fouad Sahraoui, Sebastien Galtier. 2016-09-02. Scaling of compressible magnetohydrodynamic turbulence in the fast solar wind. https://doi.org/10.3847/2041-8205/829/2/l27

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