The mechanism of constant pressure filtration of particle suspension i
n a viscoelastic fluid is studied. Effects of operating conditions on
the performance of filtration are discussed. At the beginning of a fil
tration, the elastic behavior of fluid plays an important role on the
performance of filtration, which results in a more compact cake and in
creases filtration resistance. After a period of time, the elastic eff
ect diminishes gradually, and the flow behavior of fluid transforms to
power law due to the decrease of filtration rate. A numerical program
based upon the continuity equation of cake compression and the filtra
tion equation is designed for simulating the variations of local cake
properties during a course of constant pressure filtration. The averag
e cake porosity decreases with time at the beginning of filtration and
then increases and approaches to a given value when the flow behavior
transforms to power law. The calculated results of average cake poros
ity agree very well with the experimental data when the filter chamber
is filled with cake.