Nearly Incompressible Modeling of the Solar Wind

ORAL

Abstract

We develop a three-dimensional time dependent numerical model of compressible magnetohydrodynamic fluids describing super-Alfv\'enic, 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 Alfv\'enic modes. Nonlinear cascades lead to super-Alfv\'enic turbulent motions decaying to a sub- Alfv\'enic 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.

*This work was partially supported by NASA and NSF grants.

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Authors

  • G.P. Zank

    • Department of Physics and Center for Space Plasma and Aeronomic Research (CSPAR)

  • Dastgeer Shaikh

    • Department of Physics and Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama at Huntsville, Huntsville, AL 35805
    • Department of Physics and Center for Space Plasma and Aeronomic Research (CSPAR)
    • Department of Physics and Center for Space Plasma and Aeronomic Research (CSPAR), The University of Alabama in Huntsville
    • Department of Physics and Center for Space Plasma and Aeronomic Research (CSPAR) The University of Alabama in Huntsville
    • The University of Alabama in Huntsville
    • Department of Physics, and Center for Space Plasma and Aeronomic Research (CSPAR) The University of Alabama in Huntsville 301 Sparkman Drive, Huntsvi