In-Plane Radial Fluid Flow Characterization of Fibrous Materials

Several techmques employing fluid flow to characterize the structure of fibrous materials are presented. A radial flow cell is described in which a fibrous mat with a central hole is compressed between two transparent plates. A liquid is injected into the center of the cell and the radial-spreading pattern of the liquid front is momtored with a video camera By observing the flow patterns, in-plane permeabilities and amsotropy indices are calculated which characterize the fibrous materials. By varying the spacing between the transparent plates the effect of compression on permeability is measured. Two flow techmques for measuring pore volume and pore throat distri butions on compressed mats are also described. Models are developed that describe the radial flow of Newtonian and Bingham-like fluids in the plane of the fiber mats. In the case of the Bingham-like fluid (foam) model, the yield stress parameter and the mobility can be obtained from one experiment.