Three-dimensional simulations of turbulent spectra in the local interstellar medium
Three-dimensional time dependent numerical simulations of compressible magnetohydrodynamic fluids describing super-Alfvénic, supersonic and strongly magnetized space and laboratory plasmas show a nonlinear relaxation towards a state of near incompressibility. The latter is characterized essentially...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2007-07-01
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| Series: | Nonlinear Processes in Geophysics |
| Online Access: | http://www.nonlin-processes-geophys.net/14/351/2007/npg-14-351-2007.pdf |
| Summary: | Three-dimensional time dependent numerical simulations of compressible magnetohydrodynamic fluids describing super-Alfvénic, supersonic and strongly magnetized space and laboratory plasmas show a nonlinear relaxation towards a state of near incompressibility. The latter is characterized essentially by a subsonic turbulent Mach number. This transition is mediated dynamically by disparate spectral energy dissipation rates in compressible magnetosonic and shear Alfvénic modes. Nonlinear cascades lead to super-Alfvénic turbulent motions decaying to a sub-Alfvénic regime that couples weakly with (magneto)acoustic cascades. Consequently, the supersonic plasma motion is transformed into highly subsonic motion and density fluctuations experience a passive convection. This model provides a self-consistent explaination of the ubiquitous nature of incompressible magnetoplasma fluctuations in the solar wind and the interstellar medium. |
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| ISSN: | 1023-5809 1607-7946 |