A Unified Three-dimensional Magnetohydrodynamic Model of the Solar Corona, Solar Wind, and Global Heliosphere with Turbulence Transport

Abstract We present results from a unified three-dimensional magnetohydrodynamic model of the solar corona, solar wind, and global heliosphere that incorporates turbulence transport. The fully three-dimensional model is based on Reynolds-averaged mean-flow equations coupled with transport equations for turbulence energy, cross helicity, energy difference, and correlation length scale. The computational domain extends from the coronal base to the local interstellar medium and is divided into four regions: (1) the corona, 1–30 R ⊙ ; (2) the solar wind, 30 R ⊙ –5 au; (3) the distant solar wind, 5–40 au; and (4) the global heliosphere, 40–1200 au. Representative boundary conditions are imposed at the coronal base and in the interstellar medium. Steady-state solutions are obtained sequentially using time relaxation in each of the four regions. The model accounts for Reynolds stresses, eddy viscosity, turbulent heating, electron heat conduction, Coulomb collisions between thermal protons and electrons, and—beyond 5 au—the effects of pickup protons. In this study, we add an evolution equation for the energy difference and revise the correlation length scale equation to include additional terms associated with cross helicity and eddy viscosity. We show that a region of enhanced turbulence energy forms ahead of the hydrogen wall in the outer heliosheath, and that pickup protons have a negligible influence on the angular momentum flux carried by the solar wind. We compare our simulation results with in situ observations from the Parker Solar Probe, WIND, Ulysses, and New Horizons. The simulation results show overall agreement with the observed plasma, magnetic field, and turbulence quantities.