StreamAligned Magnetohydrodynamics for Solar Wind Simulations
Abstract
We present a reduced magnetohydrodynamic (MHD) mathematical model describing the dynamical behavior of highly conducting plasmas with frozenin magnetic fields, constrained by the assumption that, there exists a frame of reference, where the magnetic field vector, $\mathbf{B}$, is aligned with the plasma velocity vector, $\mathbf{u}$, at each point. We call this solution "streamaligned MHD" (SAMHD). Within the framework of this model, the electric field, $\mathbf{E} = \mathbf{u} \times \mathbf{B} \equiv 0$, in the induction equation vanishes identically and so does the electromagnetic energy flux (Poynting flux), $\mathbf{E}\times\mathbf{B}\equiv0$, in the energy equation. At the same time, the force effect from the magnetic field on the plasma motion (the Ampere force) is fully taken into account in the momentum equation. Any steadystate solution of the proposed model is a legitimate solution of the full MHD system of equations. However, the converse statement is not true: in an arbitrary steadystate magnetic field the electric field does not have to vanish identically (its curl has to, though). Specifically, realistic treedimensional solutions for the steadystate ("ambient") solar atmosphere in the form of socalled Parker spirals, can be efficiently generated within the streamaligned MHD (SAMHD) with no loss in generality
 Publication:

arXiv eprints
 Pub Date:
 October 2021
 arXiv:
 arXiv:2110.04379
 Bibcode:
 2021arXiv211004379S
 Keywords:

 Physics  Plasma Physics;
 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 22 pages, 6 figures. Submitted to The Astrophysical Journal