The permeability of fibrous porous media

Abstract

The literature was searched for experiments and theories related to low‐Reynolds‐number flow through fibrous porous media, particularly highly porous structures. Experimental data were found for a wide range of materials, from polymer chains to fiberglass, and the results collapse reasonably well when the appropriate dimensionless co‐ordinates are employed. Of the theories, accurate solutions of Stokes equation are available for regular arrays of parallel rods, either aligned with or normal to the flow. For irregular arrays and three‐dimensional media, approximate permeabilities can be calculated from several flow models.

Permeability of electrospun fiber mats under hydraulic flow

“…Electrospun mats can be approximated as planar fibrous networks. From the review by Jackson and James [21], analytical permeability models for flow perpendicular to a 2-D array of cylinders developed by Happel [12] and by Spielman and Goren [15] fit the experimental data well in the solidity range ~0.05 to 0.3 (where solidity is defined as 1-porosity). Since Happel's equation is considerably simpler and does not involve implicit functions of permeability, Happel's model is chosen for this work.…”

Fiber deposition models in two and three spatial dimensions

“…The simulated non-dimensional permeabilities k/a 2 as a function of porosity (black triangles). White boxes and circles show the experimental results for fibrous filters [69] and compressed fiber mats [70,69], respectively. Curve 1 is an analytical prediction for cubical lattice geometry [69], curve 2 is the simulated result with fcc geometry [71] and curve 3 shows the prediction given by the Kozeny-Carman Eq.…”

“…16, where each black triangle represents the simulated permeability of one single fiber network [28]. The fiber network resembles fibrous filters, for which experimental permeability results [69] are shown in Fig. 16 with open squares.…”

“…The open circles in Fig. 16 correspond to experimental data for compressed random fiber mats [69,70].…”

Permeability of microporous carbon preforms

“…This parameter allows one to treat the fluid-solid system as a quasicontinous medium. A number of empirical relationships have been derived for packed [5] and fibrous beds, [6] and bundles of aligned fibers, [7] including correction factors for nonspherical shapes and misalignment of the fibers, as well. There is, however, no reliable equation [8] that could predict the permeability for a given microporous structure.…”