Porosity and Permeability in Ternary Sediment Mixtures

Porosity and permeability were measured in mixtures of fine, medium, and coarse sand, where the volume fraction of each of the three components was systematically varied. The porosity varies non-linearly with the volume fractions, and can be modeled with a piecewise-linear approach. The permeability also varies non-linearly with the volume fractions. Permeability can be modeled with the Kozeny-Carman equation using a recursive approach for computing the representative grain size from those of the components in the mixture

Validation of a stochastic digital packing algorithm for porosity prediction in fluvial gravel deposits

Porosity as one of the key properties of sediment mixtures is poorly understood. Most of the existing porosity predictors based upon grain size characteristics have been unable to produce satisfying results for fluvial sediment porosity, due to the lack of consideration of other porosity-controlling factors like grain shape and depositional condition. Considering this, a stochastic digital packing algorithm was applied in this work, which provides an innovative way to pack particles of arbitrary shapes and sizes based on digitization of both particles and packing space. The purpose was to test the applicability of this packing algorithm in predicting fluvial sediment porosity by comparing its predictions with outcomes obtained from laboratory measurements. Laboratory samples examined were two natural fluvial sediments from the Rhine River and Kall River (Germany), and commercial glass beads (spheres). All samples were artificially combined into seven grain size distributions: four unimodal distributions and three bimodal distributions. Our study demonstrates that apart from grain size, grain shape also has a clear impact on porosity. The stochastic digital packing algorithm successfully reproduced the measured variations in porosity for the three different particle sources. However, the packing algorithm systematically overpredicted the porosity measured in random dense packing conditions, mainly because the random motion of particles during settling introduced unwanted kinematic sorting and shape effects. The results suggest that the packing algorithm produces loose packing structures, and is useful for trend analysis of packing porosity

The Colors of Life

In My Nature Era Ash Cave - Hocking Hills Looking up to the trees and beyond, with a new perspective, of the life above the familiar.https://digitalcommons.cedarville.edu/library_photo_contest_fall_2023/1017/thumbnail.jp

Taking Flight

Captured while taking flight, the Vanessa Atalanta, a beautiful butterfly species, is exploring the new adventures of the day.https://digitalcommons.cedarville.edu/library_photo_contest_fall_2023/1016/thumbnail.jp

Porosity and Permeability in Ternary Sediment Mixtures

Permeability, k, and porosity, φ, were measured in mixtures of fine, medium, and coarse sand, where the volume fraction of each of the three components was systematically varied. The k was modeled well by the Kozeny-Carman equation for three-component mixtures by using a representative grain size parameter, d, computed by averaging the grain diameters of components recursively, with averaging methods based on whether finer components exist in sufficient volume to fill the pores within coarser components. The φ was modeled well by using linear interpolation with piecewise-planar models. We explored the use of differing numbers of piecewise-planar elements in the model, and illustrate the trade-off between the increased accuracy and the increased data requirements that both come from adding more elements. The k model is a function of both d and φ, but more sensitive to d. The k model gave results consistent with measured values when computed using either measured φ values, or values from any of the φ models

Porosity and Permeability in Ternary Sediment Mixtures

Permeability, k, and porosity, φ, were measured in mixtures of fine, medium, and coarse sand, where the volume fraction of each of the three components was systematically varied. The k was modeled well by the Kozeny-Carman equation for three-component mixtures by using a representative grain size parameter, d, computed by averaging the grain diameters of components recursively, with averaging methods based on whether finer components exist in sufficient volume to fill the pores within coarser components. The φ was modeled well by using linear interpolation with piecewise-planar models. We explored the use of differing numbers of piecewise-planar elements in the model, and illustrate the trade-off between the increased accuracy and the increased data requirements that both come from adding more elements. The k model is a function of both d and φ, but more sensitive to d. The k model gave results consistent with measured values when computed using either measured φ values, or values from any of the φ models