  Vortex flows have been found in the photosphere, chromosphere and low corona
in observations and simulations. It has been suggested that vortices play an
important role for channeling energy and plasma into the corona, but the impact
of vortex flows on the corona has not directly been studied in a realistic
setup. We investigate the role vortices play for coronal heating using high
resolution simulations of coronal loops. The vortices are not artificially
driven, but arise self-consistently from magnetoconvection. We perform 3D
resistive MHD simulations with the MURaM code. Studying an isolated coronal
loop in a Cartesian geometry allows us to resolve the structure of the loop
interior. We conduct a statistical analysis to determine vortex properties as a
function of height from the chromosphere into the corona. We find that the
energy injected into the loop is generated by internal coherent motions within
strong magnetic elements. A significant part of the resulting Poynting flux is
channeled through the chromosphere in vortex tubes forming a magnetic
connection between the photosphere and corona. Vortices can form contiguous
structures that reach up to coronal heights, but in the corona itself the
vortex tubes get deformed and eventually lose their identity with increasing
height. Vortices show increased upward directed Poynting flux and heating rate
both in the chromosphere and corona, but their effect becomes less pronounced
with increasing height. While vortices play an important role for the energy
transport and structuring in the chromosphere and low corona, their importance
higher up in the atmosphere is less clear since the swirls are less
distinguishable from their environment. Vortex tubes reaching the corona show a
complex relationship with the coronal emission.
