Fractionation of polydisperse systems: Multiphase coexistence

The width of the distribution of species in a polydisperse system is employed in a small-variable expansion, to obtain a well-controlled and compact scheme by which to calculate phase equilibria in multiphase systems. General and universal relations are derived, which determine the partitioning of the fluid components among the phases. The analysis applies to mixtures of arbitrarily many slightly polydisperse components. An explicit solution is approximated for hard spheres. [S1063-651X(99)07003-8].