It is well established that the flow of resin through the reinforcing fibres during the manufacturing of composites by liquid moulding processes follows Darcy's law. This implies that the fibre reinforcements can be characterised by its permeability through measurements can be characterised by its permeability through measurements or by the usage of permeability models based on, for instance, the detailed fibre geometry. The fibre reinforcements used for composites manufactured by liquid moulding processes are, in most cases, formed by fibres which are gathered in bundles. This results in two types of flow: A microscale flow within the fibre bundles and a mesoscale flow between the bundles. Typical length scales for the two types of flow are < 10 ㎛ and > 100 ㎛, respectively. It has been shown that the relation between the microflow and mesoflow is important for flow front phenomena such as void formation while a number of studies have indicated that the overall flow rate through the material is, to a large extent, set by the mesoflow; cf., for instance, [1, 2]. This is easily understood by noticing that the volumetric flow rate per unit area is proportional to the aquare of the characteristic on the mesoscale is as a rule of thumb, one hundred times higher or more than it is on the microscale as long as the geometry on the two scales is principally the same.