  Relativistic jets from (supermassive) black holes are typically observed in
non-thermal emission, caused by highly-relativistic electrons. Here, we study
the interrelation between three-dimensional (special) relativistic
magnetohydrodynamics, and particle acceleration in these jets. We inject
Lagrangian particles into the jet that are accelerated through diffusive shock
acceleration and radiate energy via synchrotron and inverse Compton processes.
We investigate the impact of different injection nozzles on the jet dynamics,
propagation, and the spectral energy distribution of relativistic particles. We
consider three different injection nozzles -- injecting steady, variable and
precessing jets. These jets evolve with substantially different dynamics,
driving different levels of turbulence and shock structures. The steady jet
shows a strong, stationary shock feature, resulting from a head-on collision
with an inner back-flow along the jet axis - a jet inside a jet. This shock
represents a site for highly-efficient particle acceleration for electrons upto
a few tens of TeV and should be visible in emission as a jet knot. Overall, we
find that the total number of shocks is more essential for particle
acceleration than the strength of the shocks. The precessing jet is most
efficient in accelerating electrons to high energies reaching even few hundred
TeVs, with power-law index ranging from 2.3 to 3.1. We compare different
outflow components, such as jet and the entrained material concerning particle
acceleration. For the precessing nozzle, particle acceleration in the entrained
material is as efficient as in the jet stream. This is due to the higher level
of turbulence induced by the precession motion.
