Liquid molding processes are becoming more popular among the composite
manufacturing industries due to their versatility and economy among other merits. In analyzing the
flow during the process, permeability is the most important parameter. Permeability has been
regarded as a property of the porous medium. However, in many practical cases, the value may vary
depending on the flow conditions such as the flow rate. It is speculated that this deviation is caused by
inhomogeneous microstructure of the medium. In this study, numerical simulations as well as
experimental measurements have been done to investigate the cause of deviation. Microstructure of
porous medium was modeled as an array of porous cylinders. Resin flow through the array was
simulated numerically. Simulations were performed for two different flow conditions, namely
saturated flow and unsaturated flow. Based upon the results, permeabilities were estimated and
compared for the two flow conditions. In addition, a model was proposed to predict the permeability
for different flow conditions. Results showed that experimental data were in agreement with the
prediction by the model.