A numerical model of gravity sedimentation and thickening was developed fro
m the governing two-phase flow equations for the liquid and solid phases. T
he inertial and gravity terms in the solid and liquid momentum equations we
re retained in the gravity sedimentation and thickening model. An implicit,
space-staggered finite-difference algorithm was developed for the resultin
g coupled partial differential equations. Constitutive relationships descri
bing the physical properties of the slurry were required to solve the numer
ical model. These constitutive properties describing the relationship betwe
en effective stress and porosity and between permeability and porosity were
determined experimentally and by model calibration. The model was calibrat
ed and verified using the data of dynamic porosity profiles of gravity sedi
mentation and thickening of kaolin suspensions in distilled water.