Global MHD Modeling of the Heliosphere with Turbulence Transport and Pickup Protons as Separate Fluid

Abstract:

We present initial results from a four-fluid, three-dimensional magnetohydrodynamic model of the solar wind interaction with the local interstellar medium. The unique features of the model are: (a) a three-fluid description for the charged components of the solar wind and interstellar plasmas (thermal protons, electrons, and pickup protons), (b) built-in turbulence transport equations based on Reynolds decomposition and turbulence phenomenologies and coupled with the mean-flow Reynolds-averaged equations, and (c) a solar corona/solar wind model (Usmanov et al., Astrophys. J., 788, 43, 2014) that supplies inner boundary conditions at 40 AU by computing the solar wind and magnetic field parameters outward from the coronal base. The three charged species are described by separate energy equations and are assumed to move with the same velocity. The fourth fluid in the model is the interstellar hydrogen which is treated by separate continuity, momentum and energy equations that are coupled with the charged components by the photoionization and charge exchange processes. We evaluate the effects of turbulence transport and pickup protons on the global heliospheric structure and compute the distribution of plasma, magnetic field, and turbulence parameters throughout the outer heliosphere for representative solar minimum and maximum conditions.