Improving permeability prediction for fibrous materials through a numerical investigation into pore size and pore connectivity

The application of the traditional Kozeny–Carman equation to irregular particle shapes such as those found in fibrous materials results in a poor estimation of the permeability due to two factors; inadequate description of the void size and no accounting of the pore connectivity. A shape factor is used to attempt to describe the void size but fails for this type of particle as it can only be found empirically rather than from its definition. The use of the traditional Kozeny–Carman equation also includes a constant value for the tortuosity of a material, which represents the connectivity of the voids, whereas the tortuosity should be a variable that changes depending on the shape of the particle and the degree of packing. These two factors are investigated in this study via numerical simulations to obtain a greater understanding of the role of void space and void connectivity in the prediction of permeability.