  We study non-homogeneous quantum quenches in a one-dimensional gas of
repulsive spin-$1/2$ fermions, as described by the integrable Yang-Gaudin
model. By means of generalized hydrodynamics (GHD), we analyze in detail the
real-time evolution following a sudden change of the confining potential. We
consider in particular release protocols and trap quenches, including a version
of the quantum Newton's cradle. At zero temperature, we employ a simplified
phase-space hydrodynamic picture to characterize the dynamics of the particle-
and spin-density profiles. Away from zero temperatures, we perform a thorough
numerical study of the GHD equations, and provide quantitative predictions for
different values of the temperature, external magnetic field, and chemical
potential. We highlight the qualitative features arising due to the
multi-component nature of the elementary excitations, discussing in particular
effects of spin-charge separation and dynamical polarization.
