scholarly journals Estimation of soil hydraulic and solute transport properties from field infiltration experiments

2021 ◽  
Vol 10 (14) ◽  
pp. e195101421764
Author(s):  
André Maciel Netto ◽  
Suzana Maria Gico Lima Montenegro ◽  
Ademir de Jesus Amaral
Keyword(s):  
Solute Transport ◽  
Transport Properties ◽  
Numerical Models ◽  
Three Dimensional ◽  
Solute Concentration ◽  
Water Fraction ◽  
Mobile Water ◽  
Single Ring ◽  
Long Time ◽  
Soil Hydraulic

To model water flow and solute transport in soils, hydrodynamic and hydrodispersive parameters are required as input data in the mathematical models. This work aims to estimate the soil hydraulic and solute transport properties using a ponded axisymmetric infiltration experiment using a single-ring infiltrometer along with a conservative tracer (Cl-) in the field. Single ring infiltration experiments were accomplished on an Oxisol in Areia in the state of Paraíba, Brazil (6o 58' S, 35o 41' W, and 645 m), in a 50 x 50 m grid (16 points). The unsaturated hydraulic conductivity (K) and the sorptivity (S) were estimated for short or long time analysis of cumulative three-dimensional infiltration. The single tracer technique was used to calculate mobile water fraction (Ф) by measuring the solute concentration underneath the ring infiltrometer at the end of the infiltration. Two solute transfer numerical models based on the mobile-immobile water concept were used. The mobile water fraction (Ф), the dispersion coefficient (D), and the mass transfer coefficient (a) between mobile and immobile were estimated from both the measured infiltration depth and the Cl- concentration profile underneath the infiltrometer. The classical convection-dispersion (CD) and the mobile-immobile (MIM) models showed a good agreement between calculated and experimental values. However, the lowest standard errors to the fitted parameters were obtained by the CD model.

scholarly journals Direct characterization of solute transport in unsaturated porous media using fast X-ray synchrotron microtomography

2020 ◽  
Vol 117 (38) ◽  
pp. 23443-23449 ◽  
Author(s):  
Sharul Hasan ◽  
Vahid Niasar ◽  
Nikolaos K. Karadimitriou ◽  
Jose R. A. Godinho ◽  
Nghia T. Vo ◽  
...  
Keyword(s):  
Solute Transport ◽  
High Speed ◽  
Three Dimensional ◽  
Concentration Field ◽  
Solute Concentration ◽  
Breakthrough Curves ◽  
Pore Scale ◽  
X Ray ◽  
Long Tails ◽  
Computed Microtomography

Solute transport in unsaturated porous materials is a complex process, which exhibits some distinct features differentiating it from transport under saturated conditions. These features emerge mostly due to the different transport time scales at different regions of the flow network, which can be classified into flowing and stagnant regions, predominantly controlled by advection and diffusion, respectively. Under unsaturated conditions, the solute breakthrough curves show early arrivals and very long tails, and this type of transport is usually referred to as non-Fickian. This study directly characterizes transport through an unsaturated porous medium in three spatial dimensions at the resolution of 3.25 μm and the time resolution of 6 s. Using advanced high-speed, high-spatial resolution, synchrotron-based X-ray computed microtomography (sCT) we obtained detailed information on solute transport through a glass bead packing at different saturations. A large experimental dataset (>50 TB) was produced, while imaging the evolution of the solute concentration with time at any given point within the field of view. We show that the fluids’ topology has a critical signature on the non-Fickian transport, which yet needs to be included in the Darcy-scale solute transport models. The three-dimensional (3D) results show that the fully mixing assumption at the pore scale is not valid, and even after injection of several pore volumes the concentration field at the pore scale is not uniform. Additionally, results demonstrate that dispersivity is changing with saturation, being twofold larger at the saturation of 0.52 compared to that at the fully saturated domain.

Field measured mobile water fraction for soils of contrasting texture

Soil Research ◽  
2000 ◽  
Vol 38 (6) ◽  
pp. 1131 ◽  
Author(s):  
A. E. A. Okom ◽  
R. E. White ◽  
L. K. Heng
Keyword(s):  
Hydraulic Conductivity ◽  
Solute Transport ◽  
Water Content ◽  
Time Scale ◽  
Solute Transfer ◽  
Water Fraction ◽  
Mobile Water ◽  
Immobile Water ◽  
Mobile Fraction ◽  
Fertiliser Application

For the purpose of modeling solute transport, soil water has often been simply divided into an essentially mobile fraction, q m , which is active in solute transport, and an apparently immobile fraction, q im . Distinction between q m and q im was sought using the disc permeameter technique. This study examines unsaturated estimates of mobile water content at suction heads, h, of 20, 40, 80, and 120 mm for several soils ranging in texture from sand to clay. Following infiltration of 35 mm depth of 0.01 M KBr into initially dry soils, soil samples were collected from below the base of the disc permeameter and analysed for tracer concentrations which enabled partitioning of mobile and immobile water. Hydraulic conductivity and sorptivity were also derived from the infiltration data. The results show the expected non-linearity of hydraulic conductivity and sorptivity with suction. The mobile water expressed as a fraction, f, of the volumetric water content q (f = q m / q ) was generally found to range from 0.7 to 0.95, with an average of 0.85. The exception was one site for which f was ª 0.50. These values of f are comparable to those derived from leaching studies reported in the literature. An important finding of this work is that within the range of suctions measured, the mobile fraction was independent of suction. A possible explanation for this observation is that the soil capillary forces were dominant during the time scale of the experiment and therefore rapidly drew the invading solution. This finding could have important implications for fertiliser application. Furthermore, this result suggests that the assumption of a negligible solute transfer coefficient, a , between the mobile and immobile domains may be valid within the time scale of this method of measuring the mobile water content.

scholarly journals Non-Fickian Solute Transport in Rough-Walled Fractures: The Effect of Contact Area

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2049 ◽  
Author(s):  
Yingtao Hu ◽  
Wenjie Xu ◽  
Liangtong Zhan ◽  
Zuyang Ye ◽  
Yunmin Chen
Keyword(s):  
Solute Transport ◽  
Contact Area ◽  
Concentration Distribution ◽  
Preferential Flow ◽  
Three Dimensional ◽  
Solute Concentration ◽  
Breakthrough Curves ◽  
Contact Areas ◽  
Fracture Surfaces ◽  
Early Arrival

The influence of contact area, caused by normal deformation, on fluid flow and solute transport through three-dimensional (3D) rock fractures is investigated. Fracture surfaces with different Hurst exponents (H) were generated numerically using the modified successive random addition (SRA) method. By applying deformations normal to the fracture surface (Δu), a series of fracture models with different aperture distributions and contact area ratios (c) were simulated. The results show that the contact area between the two fracture surfaces increases and more void spaces are reduced as deformation (Δu) increases. The streamlines in the rough-walled fractures show that the contact areas result in preferential flow paths and fingering type transport. The non-Fickian characteristics of the “early arrival” and “long tail” in all of the breakthrough curves (BTCs) for fractures with different deformation (Δu) and Hurst parameters (H) were determined. The solute concentration distribution index (CDI), which quantifies the uniformity of the concentration distribution within the fracture, decreases exponential as deformation (Δu) and/or contact area ratios (c) increase, indicating that increased contact area can result in a larger delay rate of mass exchange between the immobile zone around the contact areas and the main flow channel, thus, resulting in a longer time for the solute to fill the entire fracture. The BTCs were analyzed using the continuous time random walk (CTRW) inverse model. The inverse modeling results show that the dispersion exponent β decreases from 1.92 to 0.81 as c increases and H decreases, suggesting that the increase in contact area and fracture surfaces enhance the magnitude of the non-Fickian transport.

A Layer-Integrated Model of Solute Transport in Heterogeneous Media

2014 ◽  
Vol 6 (06) ◽  
pp. 699-717
Author(s):  
Hung-En Chen ◽  
Hui-Ping Lee ◽  
Shih-Wei Chiang ◽  
Tung-Lin Tsai ◽  
Jinn-Chuang Yang
Keyword(s):  
Solute Transport ◽  
Heterogeneous Media ◽  
Three Dimensional ◽  
Concentration Field ◽  
Quadratic Function ◽  
Integrated Approach ◽  
Solute Concentration ◽  
Two Dimensional ◽  
One Dimensional ◽  
Proposed Model

AbstractThis study presents a numerical solution to the three-dimensional solute transport in heterogeneous media by using a layer-integrated approach. Omitting vertical spatial variation of soil and hydraulic properties within each layer, a three-dimensional solute transport can be simplified as a quasi-three-dimensional solute transport which couples a horizontal two-dimensional simulation and a vertical one-dimensional computation. The finite analytic numerical method was used to discretize the derived two-dimensional governing equation. A quadratic function was used to approximate the vertical one-dimensional concentration distribution in the layer to ensure the continuity of concentration and flux at the interface between the adjacent layers. By integration over each layer, a set of system of equations can be generated for a single column of vertical cells and solved numerically to give the vertical solute concentration profile. The solute concentration field was then obtained by solving all columns of vertical cells to achieve convergence with the iterative solution procedure. The proposed model was verified through examples from the published literatures including four verifications in terms of analytical and experimental cases. Comparison of simulation results indicates that the proposed model satisfies the solute concentration profiles obtained from experiments in time and space.

The measured mobile-water content of an unsaturated soil as a function of hydraulic regime

Soil Research ◽  
1995 ◽  
Vol 33 (3) ◽  
pp. 397 ◽  
Author(s):  
BE Clothier ◽  
L Heng ◽  
GN Magesan ◽  
I Vogeler
Keyword(s):  
Solute Transport ◽  
Water Content ◽  
Sandy Loam ◽  
Pure Water ◽  
Solute Concentration ◽  
Petroleum Engineering ◽  
Spatial Distance ◽  
Water Fraction ◽  
Hydraulic Regime ◽  
Single Mass

To account for observations of preferential solute transport through soil, increasingly models are used in which the total water content of the soil (�, m3 m-3) is partitioned into an essentially mobile phase (8,) and an apparently immobile fraction (�im). However, few methods exist for measuring this separation in the field. Here we use the recently proposed, disc permeameter technique. Following infiltration with a tracer, measurements of the resident solute concentration directly under the disc are used to infer the �m-�im partitioning. For Manawatu fine sandy loam in situ, we applied this technique at the three pressure heads (ho) of -20, -40 and -150 mm, in order to deduce the influence of the hydraulic regime on the soil water fraction �m/� that appears to be actively involved in solute transport during infiltration. When a depth I of between 15 and 25 mm of KBr tracer was added to soil already wet by pure water to h,, the measured mobile fraction �m/� rose from 0.41 at -20 mm, through 0.50 at -40, to 0.64 at the most unsaturated head of -150 mm. Thus, less evidence of preferential solute transport was recorded with decreasing ho. The spatial distance between the preferential paths was observed to range from 20 to 150 mm, the separation increasing and the pathways becoming more diffuse with decreasing h,. Depthwise dispersion of the invading solute thus increased with ho. At the two higher heads, when I =80mm of KBr was allowed to infiltrate, the �m/�, inferred from the resident concentration observed directly under the disc, now also became 0.65. For ho = -40 mm, the measured rise in the resident concentration under the disc, with I, could be predicted using a dispersivity, �, of 20 mm in the approximation provided by the 1-D form of the convective dispersion equation. When 15-25 mm tracer was applied directly to initially dry soil (� = 0.3), capillary forces drew the invading solute from the disc with much less dispersion, such that the resident concentration under the disc rose more rapidly with I. Now �m/� was found to be virtually 0.65 at all the heads. In several experiments at h, = -40 mm, ethanol was used as the solvent for the tracer. No change in the measured �m/� was observed. Thus hydrophobicity was deemed not to be a factor in our measurement of 8,/B being consistently about 0.65. An attempt was made to parameterize the diffusive-exchange scheme that the Coats and Smith (1964) model, taken from petroleum engineering, proposes as the link between the mobile and immobile domains. However, our observations at ho = -20 mm suggest that no single mass-transfer coefficient 5 can describe this solute exchange. Over the first few days, a � value of 0.5 day-1 seemed reasonable, but over the next fortnight there appeared no further interdomain exchange of solute between the two domains.

Effects of Velvet Antler Polypeptide-Collagen/Chitosan Materials on Proliferation of Osteoblast

2013 ◽  
Vol 380-384 ◽  
pp. 4295-4298
Author(s):  
Wen He Zhu ◽  
Jun Jie Xu ◽  
Wei Zhang ◽  
Yan Li ◽  
Xiao Jing Lu ◽  
...  
Keyword(s):  
Drug Treatment ◽  
Bone Defect ◽  
Three Dimensional ◽  
Chitosan Scaffold ◽  
Release Drug ◽  
Dimensional Network ◽  
Velvet Antler ◽  
Result Show ◽  
Long Time ◽  
Velvet Antler Polypeptide

A highly osteogenic hybrid bioabsorbable scaffold was developed for bone reconstruction. Though the use of a bioabsorbable collagen and chitosan scaffold for loading velvet antler polypeptide to repair bone defect and drug treatment. Velvet antler polypeptide and collagen were extracted for developing the compounded material. The SEM results show that the collagen and chitosan scaffold maintain the natural three dimensional network structures. The cell proliferation experiment result show that the can promote the osteoblast proliferation for a long time . These results indicated that this compound scaffold can sustainable to release drug and is a good material in bone defect and drug treatment.

Research on cargo-loading optimization based on genetic and fuzzy integration

2021 ◽  
Vol 40 (4) ◽  
pp. 8493-8500
Author(s):  
Yanwei Du ◽  
Feng Chen ◽  
Xiaoyi Fan ◽  
Lei Zhang ◽  
Henggang Liang
Keyword(s):  
Genetic Algorithm ◽  
Mathematical Model ◽  
Three Dimensional ◽  
Distribution Center ◽  
Long Time ◽  
Low Efficiency ◽  
Decision Making Model ◽  
The Mathematical Model ◽  
Loading Scheme

With the increase of the number of loaded goods, the number of optional loading schemes will increase exponentially. It is a long time and low efficiency to determine the loading scheme with experience. Genetic algorithm is a search heuristic algorithm used to solve optimization in the field of computer science artificial intelligence. Genetic algorithm can effectively select the optimal loading scheme but unable to utilize weight and volume capacity of cargo and truck. In this paper, we propose hybrid Genetic and fuzzy logic based cargo-loading decision making model that focus on achieving maximum profit with maximum utilization of weight and volume capacity of cargo and truck. In this paper, first of all, the components of the problem of goods stowage in the distribution center are analyzed systematically, which lays the foundation for the reasonable classification of the problem of goods stowage and the establishment of the mathematical model of the problem of goods stowage. Secondly, the paper abstracts and defines the problem of goods loading in distribution center, establishes the mathematical model for the optimization of single car three-dimensional goods loading, and designs the genetic algorithm for solving the model. Finally, Matlab is used to solve the optimization model of cargo loading, and the good performance of the algorithm is verified by an example. From the performance evaluation analysis, proposed the hybrid system achieve better outcomes than the standard SA model, GA method, and TS strategy.

scholarly journals Experimental and Numerical Investigation of 3D Dam-Break Wave Propagation in an Enclosed Domain with Dry and Wet Bottom

2021 ◽  
Vol 11 (12) ◽  
pp. 5638
Author(s):  
Selahattin Kocaman ◽  
Stefania Evangelista ◽  
Hasan Guzel ◽  
Kaan Dal ◽  
Ada Yilmaz ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Numerical Models ◽  
Three Dimensional ◽  
Dam Break ◽  
Dam Failure ◽  
Navier Stokes ◽  
Negative Wave ◽  
Through Flow ◽  
Instantaneous Removal ◽  
Surface Patterns

Dam-break flood waves represent a severe threat to people and properties located in downstream regions. Although dam failure has been among the main subjects investigated in academia, little effort has been made toward investigating wave propagation under the influence of tailwater depth. This work presents three-dimensional (3D) numerical simulations of laboratory experiments of dam-breaks with tailwater performed at the Laboratory of Hydraulics of Iskenderun Technical University, Turkey. The dam-break wave was generated by the instantaneous removal of a sluice gate positioned at the center of a transversal wall forming the reservoir. Specifically, in order to understand the influence of tailwater level on wave propagation, three tests were conducted under the conditions of dry and wet downstream bottom with two different tailwater depths, respectively. The present research analyzes the propagation of the positive and negative wave originated by the dam-break, as well as the wave reflection against the channel’s downstream closed boundary. Digital image processing was used to track water surface patterns, and ultrasonic sensors were positioned at five different locations along the channel in order to obtain water stage hydrographs. Laboratory measurements were compared against the numerical results obtained through FLOW-3D commercial software, solving the 3D Reynolds-Averaged Navier–Stokes (RANS) with the k-ε turbulence model for closure, and Shallow Water Equations (SWEs). The comparison achieved a reasonable agreement with both numerical models, although the RANS showed in general, as expected, a better performance.

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