A method for measuring Darcian flow permeability of thin compressed fibre mats

A method for measuring the Darcian permeability coefficient of thin samples of soft porous materials under mechanical compression was developed. The method includes an apparatus and an experimental procedure both deviced in the purpose of minimizing uncertainty of the results. The flow permeability of porous materials can be measured using both liquids and gases. Here, air flow was used in measuring the dependence of transverse flow permeability on the degree of compression for wet pressing felt, cardboard and newsprint. The experimental results were compared with numerical results from an ab-initio method obtained by combining direct numerical flow simulation and X-ray microtomography. The maximum deviation between experimental and numerical results was found to be less than 30%. Preliminary results indicate that the basis weight effect obtained with air using the present method is considerably weaker than that found in earlier studies for water flow.