  We derive an analytical connection between kinetic relaxation rate and bulk
viscosity of a relativistic fluid in d spatial dimensions, all the way from the
ultra-relativistic down to the near non-relativistic regime. Our derivation is
based on both Chapman-Enskog asymptotic expansion and Grad's method of moments.
We validate our theoretical results against a benchmark flow, providing further
evidence of the correctness of the Chapman-Enskog approach; we define the range
of validity of this approach and provide evidence of mounting departures at
increasing Knudsen number. Finally, we present numerical simulations of
transport processes in quark gluon plasmas, with special focus on the effects
of bulk viscosity which might prove amenable to future experimental
verification.
