Coefficient of permeability determined by measurable parameters.
Selection of a coefficient of permeability or the hydraulic conductivity in practical situations has required a fair amount of judgment and the expectation of accuracy can range over an order of magnitude. A determination of the coefficient based on measurable characteristics would greatly reduce the judgment aspect. The coefficient of permeability of a porous media can be derived from the following measurable parameters: the density and viscosity of the permeating fluid, the porosity of the media, the average hydraulic radius of the pores, and the gravitation constant. The hydraulic radius is calculated from the grain size distribution analysis of the porous media assuming spherical particles and a factor to account for the shape of the particles. The shape factor ranges from 1.0 to 1.4 in the extreme but, for common porous media, ranges only from 1.0 to about 1.1. All of the variables, except the shape factor, are measurable by standard test procedures. An important advantage of using this procedure for determining permeability is that the factors can be visualized as part of the physical flow process. The procedure assumes laminar flow and applies equally to liquid or gas fluids.
Barr
D W
DW
Barr Engineering Co., 4700 West 77th St., Minneapolis, MN 55435, USA. dbarr@barr.com
D019015:Geologic Sediments; D008962:Models, Theoretical; D010539:Permeability; D055585:Physical Phenomena; D010825:Physics; D012987:Soil; D014881:Water Supply
D012987:Soil