Speaker
Description
It is a challenge to construct models of realistic phenomena in the solar corona, but it is a requirement to validate the model results against real observed structures, such as coronal EUV-bright loops and coronal Doppler shifts. On the one hand, if we aim to include self-consistently driven convection below the photosphere to have a realistic driving, the photospheric magnetic field is likely not the same as in the real photosphere. On the other hand, when we prescribe realistic vertical magnetic fields in the photosphere, the convection can not be included and an artificial granulation driver has to be implemented. While the former can never exactly reproduce the photospheric conditions and hence structures in the corona, the latter has at least a chance if the granulation driver is realistic enough. Further complications arise from numerical necessities such as explicit diffusivity in the MHD equations, such as the viscosity, the heat conduction, and the magnetic diffusivity. Those diffusivities are needed to keep numerical errors under a controlled and insignificant level. In this work we discuss how such diffusivities need to be chosen according to the grid spacing. This allows us to simulate a large coronal EUV-bright loop between two pores, where we also see some match to observed Doppler shifts in Fe-XII.