3D numerical simulations of torsional Alfvén waves in solar flux tubes
Abstract
Observations have shown that Alfvén waves are ubiquitous in the solar atmosphere. Recently, torsional Alfvén waves in flux tubes have been first detected. Here, we perform numerical simulations of torsional Alfvén waves and study their nonlinear evolution. We consider a cylindrical, radially inhomogeneous, and straight magnetic flux tube that is line-tied at two rigid walls representing the solar photosphere. Standing torsional Alfvén waves are excited by perturbing the azimuthal component of the velocity. The nonlinear evolution of these waves is obtained with the PLUTO code, which solves the ideal MHD equations using a finite-volume formulation with adaptive mesh refinement. We find that the evolution of the waves is heavily affected by the phase mixing process, which generates small scales across the magnetic field direction. In the case of low amplitudes, the simulations are compared with the results predicted by linear theory. In the fully nonlinear case, we study how the later evolution of phase mixing triggers Kelvin-Helmholtz instabilities.
- Publication:
-
XIV.0 Scientific Meeting (virtual) of the Spanish Astronomical Society
- Pub Date:
- July 2020
- Bibcode:
- 2020sea..confE.195D