Limitations of Darcy's Law in Glass Bead Porous Media
Boersma, L. | Lindstrom, F. T. | Saxena, S. K.
In a series of dispersion experiments in porous systems made up of glass beads, it was found that for flow of water through small pores at low gradients, flow rates are not proportional to the hydraulic gradient but are proportional to this gradient raised to the power 1/n, where n > 1. These results agree with literature reports which have indicated that for flow through small pores, the flow fields undergo a change from Newtonian to non-Newtonian behavior. The deviations have been attributed to force fields associated with the clay minerals, changes in the clay fabric making up the porous system, and electro-viscous effects. In these experiments, the porous systems were made up of glass beads so that all effects attributed to clay-water interactions could be ruled out. The functional relationship between the factor 1/n and pore radius r was found to be approximated by 1/n = 1 − exp(−1.32r⁰.³¹).Show more [+] Less [-]