In this study, the Hagen–Poiseuille formula has been used to establish
the equation expressing the relationship between permeability of interyarn interstices
and fabric structures. Validation with experimental data shows that interyarn
porosity has a very strong influence on fabric permeability. The stepwise regression
method has been used to explore the permeability of interfiber interstices.
The prediction equation has been developed focusing on the permeability of interyarn
pores and the overall fabric cover factor. One set of worsted fabrics is used to
validate the equation. It shows that except for fabrics with z/z twist yarns or twistless
filaments, the predicted equation gives a good accuracy with an average error of
13%.