Fractal calculation of air permeability of nonwoven fabrics

A fractal permeability model for nonwoven fabrics is developed based on the fractal characteristics of pores within them. The fractal permeability is found to be related to pore area fractal dimension, tortuosity fractal dimension, size of fibers, the maximum and minimum pore sizes, fabric thickness, and the effective porosity of a medium. To verify the validity of the proposed model, experimental work was conducted on a set of nonwoven fabrics, and the predicted air permeability was compared with the experimental results. Good concordance was found between them. Meantime, the model was also compared with the existing models and is proved to be more accurate.