New mathematical models are proposed that predict fluid flow pressure gradients in
gelcast ceramic foam diesel exhaust particulate filters by considering the foam structure
conceptually as serially connected orifices. The resulting multiple orifice mathematical (MOM)
model is based on the sum of a viscous term derived from an extended Ergun model and the
kinetic energy loss derived from the Bernoulli and conservation of mass equations. The MOM
model was calibrated using experimental data obtained from measuring the air flowrate and
pressure drop across a physical large-scale three-dimensional model of a cellular foam structure
produced using rapid manufacturing techniques. The calibrated model was then validated using
fluid flow data obtained from gelcast ceramic foam filters of various cell sizes and was found to
require no empirical recalibration for each gelcast ceramic foam sample. The MOM model for
clean filters was extended to predict pressure gradients of filters loaded with particulate matter
(PM). The prediction of pressure gradients through gelcast ceramic filters using the MOM model
for clean and PM-loaded cases was shown to be in reasonable agreement with experimental data.
The models were finally applied to design a filter for a turbocharged, charge-cooled, 2.0 l, fourstroke,
common rail, direct injection passenger car diesel engine
