  We present an analytical derivation of the transport coefficients of a
relativistic gas in (2+1) dimensions for both Chapman-Enskog (CE) asymptotics
and Grad's expansion methods. Moreover, we develop a systematic calibration
method, connecting the relaxation time of relativistic kinetic theory to the
transport parameters of the associated dissipative hydrodynamic equations.
Comparison between the analytical results and numerical simulations, shows that
the CE method correctly captures dissipative effects, while Grad's method does
not. The resulting calibration procedure based on the CE method opens the way
to the quantitative kinetic description of dissipative relativistic fluid
dynamics under fairly general conditions, namely flows with strongly
non-linearities, in non-ideal geometries, across both ultra-relativistic and
near-non-relativistic regimes.
