The effect of capillary forces on the pressure differential required for infiltration of square and hexagonal arrays of parallel fibers has been evaluated by deriving equations which include the contact angle, fiber diameter, and volume fraction. Three models have been considered as fol-lows: (a) unidirectional liquid flow normal to the fibers, (b) bidirectional flow normal to the fibers, and (c) three-dimensional flow. The three-dimensional model predicts the lowest pressure for infiltration. A comparison is made between the required pressure differential for infiltration based on the work of immersion and capillary forces. The required pressure differentials based on capillary forces for contact angles greater than 90 deg are always greater than pressure dif-ferentials calculated from the work of immersion.
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