  During Parker Solar Probe's first orbit, the solar wind plasma has been
observed in situ closer than ever before, the perihelion on November 6th 2018
revealing a flow that is constantly permeated by large amplitude Alfv\'enic
fluctuations. These include radial magnetic field reversals, or switchbacks,
that seem to be a persistent feature of the young solar wind. The measurements
also reveal a very strong, unexpected, azimuthal velocity component. In this
work, we numerically model the solar corona during this first encounter,
solving the MHD equations and accounting for Alfv\'en wave transport and
dissipation. We find that the large scale plasma parameters are well
reproduced, allowing the computation of the solar wind sources at Probe with
confidence. We try to understand the dynamical nature of the solar wind to
explain both the amplitude of the observed radial magnetic field and of the
azimuthal velocities.
