摘要：Aims. We aim to study the standing fundamental kink mode of coronal
loops in the nonlinear regime, investigating the changes in energy evolution in the
cross-section and oscillation amplitude of the loop which are related to nonlinear
effects, in particular to the development of the Kelvin-Helmholtz instability (KHI).
Methods. We run ideal, high-resolution three-dimensional (3D)
magnetohydrodynamic (MHD) simulations, studying the influence of the initial velocity
amplitude and the inhomogeneous layer thickness. We model the coronal loop as a straight,
homogeneous magnetic flux tube with an outer inhomogeneous layer, embedded in a straight,
homogeneous magnetic field.
Results. We find that, for low amplitudes which do not allow for the KHI
to develop during the simulated time, the damping time agrees with the theory of resonant
absorption. However, for higher amplitudes, the presence of KHI around the oscillating
loop can alter the loop’s evolution, resulting in a significantly faster damping than
predicted by the linear theory in some cases. This questions the accuracy of seismological
methods applied to observed damping profiles, based on linear theory.
