Unsaturated hydraulic conductivity modeling for porous media with two fractal regimes

Geoderma ◽  
2013 ◽  
Vol 207-208 ◽  
pp. 268-278 ◽  
Author(s):  
Allen G. Hunt ◽  
Behzad Ghanbarian ◽  
Kenneth C. Saville
Keyword(s):  
Porous Media ◽  
Hydraulic Conductivity ◽  
Unsaturated Hydraulic Conductivity ◽  
Conductivity Modeling

Historical development of soil-water physics and solute transport in porous media

2007 ◽  
Vol 7 (1) ◽  
pp. 59-66 ◽  
Author(s):  
D.E. Rolston
Keyword(s):  
Porous Media ◽  
Hydraulic Conductivity ◽  
Solute Transport ◽  
Soil Water ◽  
20Th Century ◽  
Water Flow ◽  
Unsaturated Soils ◽  
Transport Processes ◽  
Transport In Porous Media ◽  
Unsaturated Hydraulic Conductivity

The science of soil-water physics and contaminant transport in porous media began a little more than a century ago. The first equation to quantify the flow of water is attributed to Darcy. The next major development for unsaturated media was made by Buckingham in 1907. Buckingham quantified the energy state of soil water based on the thermodynamic potential energy. Buckingham then introduced the concept of unsaturated hydraulic conductivity, a function of water content. The water flux as the product of the unsaturated hydraulic conductivity and the total potential gradient has become the accepted Buckingham-Darcy law. Two decades later, Richards applied the continuity equation to Buckingham's equation and obtained a general partial differential equation describing water flow in unsaturated soils. For combined water and solute transport, it had been recognized since the latter half of the 19th century that salts and water do not move uniformly. It wasn't until the middle of the 20th century that scientists began to understand the complex processes of diffusion, dispersion, and convection and to develop mathematical formulations for solute transport. Knowledge on water flow and solute transport processes has expanded greatly since the early part of the 20th century to the present.

DEM-aided method for predicting the hydraulic properties with particle-size distribution of porous media

2019 ◽  
Vol 36 (5) ◽  
pp. 1716-1743 ◽  
Author(s):  
Han-Cheng Dan ◽  
Zhuo-Min Zou ◽  
Jia-Qi Chen ◽  
An-Ping Peng
Keyword(s):  
Particle Size ◽  
Porous Media ◽  
Hydraulic Conductivity ◽  
Hydraulic Properties ◽  
Volume Fraction ◽  
Size Distributions ◽  
Content Type ◽  
Unsaturated Hydraulic Conductivity ◽  
Critical Volume Fraction ◽  
The Relationship

Purpose The soil water retention curve (SWRC) and unsaturated hydraulic conductivity (UHC) are crucial indices to assess hydraulic properties of porous media that primarily depend on the particle and pore size distributions. This study aims to present a method based on the discrete element model (DEM) and the typical Arya and Paris model (AP model) to numerically predict SWRC and UHC. Design/methodology/approach First, the DEM (PFC3D software) is used to construct the pore and particle size distributions in porous media. The number of particles is calculated according to the AP model, which can be applied to evaluate the relationship between the suction head and the moisture of porous media. Subsequently, combining critical path analysis (CPA) and fractal theory, the air entry value is applied to calculate the critical pore radius (CPR) and the critical volume fraction (CVF) for evaluating the unsaturated hydraulic conductivity. Findings This method is validated against the experimental results of 11 soils from the clay loam to the sand, and then the scaling parameter in the AP model and critical volume fraction value for many types of soils are presented for reference; subsequently, the gradation effect on hydraulic property of soils is analyzed. Furthermore, the calculation for unbound graded aggregate (UGA) material as a special case and a theoretical extension are provided. Originality/value The presented study provides an important insight into the relationship between the heterogeneous particle and hydraulic properties by the DEM and sheds light on the directions for future study of a method to investigate the hydraulic properties of porous media.

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