QUALITATIVE-ANALYSIS OF 2-FLUID BIANCHI COSMOLOGIES

We give a qualitative analysis of the evolution of two-fluid orthogonal Bianchi cosmologies. It is shown that the asympotic behaviour at early and late times is approximated by the evolution of the associated single fluid models. The qualitative analysis is given in detail for the Friedman-Robertson-Walker models and the orthogonal Bianchi II models with partial isotropy. All asymptotic and intermediate states of the evolution are given explicitly. Inflationary two-fluid models, and in particular, the cosmic no-hair theorem, are also discussed.