Showing papers on "Effective porosity published in 1981"
TL;DR: The pseudopermeability coefficient (k p ) of water flow in aquifers is defined in this article, where q = k P i N A, where N varies from 1 for laminar flow to 0.5 for turbulent flow.
Abstract: The water transmission characteristics of rock formations are far more variable than those of most soils. The flow conduits include (1) primary porosity, the voids between mineral grains or fragments; (2) genetic porosity, voids which developed within the rock during its formation; and (3) secondary porosity, the joints, shear zones, and other cracks that formed subsequent to deposition. The porosity changes over time as the voids both fill up and become enlarged. The flow patterns are complex, with tortuous paths between the different forms of porosity. Laminar and turbulent flow occur simultaneously, depending on void size and energy gradients. The flow can be characterized by a variable pseudopermeability coefficient, k p , in the expression q = k P i N A, where N varies from 1 for laminar flow to 0.5 for turbulent flow. Laboratory tests are useless unless the sample size is an order of magnitude larger than the secondary porosity spacing. Field measurements in bore holes or an evaluation of subregional discharge is necessary for making a realistic evaluation of k P of rock aquifers. There are likely to be large variations in k P depending on location, time, and changes in the groundwater environment.
2 citations
TL;DR: In this paper, the effect of porosity and tortuosity of the flow path on desorption has been studied in four partially hydrolyzed kaolinite sediments presenting different fabrics, non-linearity of the fluid flux-pressure gradient relationship is related to changes in effective porosity.
Abstract: UNSATURATED flow on desorption has been studied in four partially hydrolyzed kaolinite sediments presenting different fabrics, Non-linearity of the fluid flux-pressure gradient relationship is shown to be related to changes in effective porosity and tortuosity of the flow path. Laminar flow is shown in terms of fricton factor-Reynolds number relationship.
1 citations