Two-Scale Modeling Approach to Predict Permeability of Fibrous Media

We previously demonstrated how one can develop a 3-D geometry to model the fibrous microstructure of a nonwoven fiberweb and use it to simulate its permeability at fiber level [1-6]. Developing 3-D models of most nonwoven fabrics (bonded fiberwebs), however, is cumbersome, as in the case of hydroentangled fabrics, for instance. In such cases, microscopic techniques are often used to generate 3-D images of the media's microstructures. Nevertheless, whether the microstructure is modeled or obtained from 3-D imaging, extensive computational resources are required to use them in fluid flow simulations [7]. To circumvent this problem, a two-scale modeling approach is proposed here that allows us to simulate the entire thickness of a commercial fabric/filter on a personal computer. In particular, the microscale permeability of a hydroentangled nonwoven is computed using 3-D reconstructed microstructures obtained from Digital Volumetric Imaging (DVI). The resulting microstructural permeability tensors are then used in a macroscale porous model to simulate the flow through the material's thickness and the calculation of its overall permeability.