  We consider a Friedmann-Robertson-Walker spacetime filled with both viscous
radiation and nonviscous dust. The former has a bulk viscosity which is
proportional to an arbitrary power of the energy density, i.e. $\zeta \propto
\rho_v^{\nu}$, and viscous pressure satisfying a nonlinear evolution equation.
The analysis is carried out in the context of dynamical systems and the
properties of solutions corresponding to the fixed points are discussed. For
some ranges of the relevant parameter $\nu$ we find that the trajectories in
the phase space evolve from a FRW singularity towards an asymptotic de Sitter
attractor, confirming and extending previous analysis in the literature. For
other values of the parameter, instead, the behaviour differs from previous
works.
