In LCM processes of fiber-reinforced composite manufacturing, resin is injected into a closed mold with a preplaced stationary fiber preform. If these preforms are created from fiber tows, resin progression at the microlevel during infiltration is often non-uniform. Consequently, macroscopic description of the filling phase requires a theory of flow through unsaturated porous media in which the transition (partly saturated) region must be taken into account. Unsaturated flows must consider surface tension effects; therefore, capillary pressure and relative permeability must be included in governing equations. This paper presents a methodology to determine relative permeability and macroscopic capillary pressure for simple flows. The results lead to important conclusions and the methodology can be generalized to other flow fields.