Rheological properties are of great interest in oil & gas, pharmaceutical, food, plastics and cosmetic industries which process different types of multi-phase suspensions. Review of existing literature on rheological studies and experiments are conducted to verify the effect of total solid concentration � on the viscosity of mono-disperse and bi-disperse suspensions.

Gravity filtration involves flow of fluid through a porous filter medium and a time dependent cake layer which act as additional filter media. Filtration rate and cake build up as a function of time are examined for mono- and bi-disperse suspensions through theory and experimentation. Darcy's Law, which describes fluid flow through porous media, was applied along with the Kynch theory of sedimentation, which provides the basis for analyzing low concentration (� ≤ 0.1) cake formation. Experiments were performed to study the effects of varying particle sizes (45 μm ≤ d ≤ 1400 μm) and total solid concentration � on both the formation rate of the cake layer and its flow permeability (k) in conjunction with the filter media. Two CCD cameras were used to capture images of the cake formation and fluid drainage processes, and subsequent image and theoretical analysis found a constant pressure loss due to the permeability of the filter media, whereas the pressure loss due to the cake formation varies as a function of time, � and d.