NONEQUILIBRIUM PHASE-TRANSITION IN A BINARY MIXTURE

A non-equilibrium phase transition is identified from an exact solutio n of the Boltzmann equation describing a binary mixture under shear fl ow in the tracer limit (n(1)/n(2) much less than 1): there exists a cr itical value a(c) (which depends on the mass ratio m(1)/m(2) and the f orce constant ratios) of the shear rate such that lim(n1/n2-->0)E(1)/E = 0 for a < a(c) (disordered phase), while lim(n1/n2-->0) E(1)/E not equal 0 for a > a(c) (ordered phase), where E(1)/E is the relative con tribution of the tracer species to the total energy. This phase transi tion is absent when m(1)/m(2) is sufficiently large and/or the strengt h of the interactions 2-2 is sufficiently larger than that of 1-2.