Abstract
The equilibrium hard-sphere fluid is used to model the structure of dispersions of identical impenetrable spheres within a matrix. Pair-correlation functions adjusted to Monte Carlo simulation results, and reported in the literature, are used to compute the contribution of pairs of spheres to the effective thermal (or electrical) conductivity of the dispersions. An improved form of Maxwell's equation is proposed, which is correct to order
φ
2, where φ is the volume fraction of the dispersed phase. A comparison with experimental measurements shows good agreement over a wide range of conditions. The approach fails for highly concentrated dispersions of very conducting spheres. Alternative models are discussed which are appropriate in this limit.