The packing limit is not a fixed quantity and may change according to the number of particles present within a given volume and the diameter of the particles. Small particles accumulate in between larger particles increasing the packing limit. For a binary mixture FLUENT uses the correlations proposed by [ 101].
For a binary mixture with diameters , the mixture composition is defined as
The maximum packing limit for the mixture is given by
otherwise, the maximum packing limit for the binary mixture is
The packing limit is used for the calculation of the radial distribution function.