  New, analytic solutions of relativistic viscous hydrodynamics are presented,
describing expanding fireballs with Hubble-like velocity profile and
ellipsoidal symmetry, similar to fireballs created in heavy ion collisions. We
find that with these specifications, one obtains solutions where the shear
viscosity essentially does not influence the time evolution of the system, thus
these solutions are particularly adept tools to study the effect of bulk
viscosity alone, which always results in a slower decrease of energy density as
well as temperature compared to the case of perfect fluid. We investigate
different scenarios for the bulk viscosity and find qualitatively different
effects on the time evolution which suggests that there is a possibility to
infer the value of bulk viscosity from energy density and temperature
measurements in high-energy heavy-ion collisions.
