Centrifuge modeling of one-step outflow tests for unsaturated parameter estimations

Nakajima, Hideo; Stadler, Alan T.

doi:10.5194/hess-10-715-2006

Cited by 15 publications

(17 citation statements)

References 33 publications

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“…Note that high-speed centrifugal methods during the last few decades have become relatively standard in many fields (such as in soil physics, the petroleum industry, and environmental and geotechnical engineering) for measuring saturated and unsaturated hydraulic conductivities or for studying various flow and transport processes. Example applications of this module are given by Nakajima and Stadler (2006) and van den Berg et al (2009).…”

Section: Main Modulementioning

confidence: 99%

Recent Developments and Applications of the HYDRUS Computer Software Packages

Šimůnek

Genuchten

Šejna³

2016

Vadose Zone Journal

746

336

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The HYDRUS-1D and HYDRUS (2D/3D) computer software packages are widely used finite-element models for simulating the one-and two-or three-dimensional movement of water, heat, and multiple solutes in variably saturated media, respectively. In 2008, Šimůnek et al. (2008b) described the entire history of the development of the various HYDRUS programs and related models and tools such as STANMOD, RETC, ROSETTA, UNSODA, UNSATCHEM, HP1, and others. The objective of this manuscript is to review selected capabilities of HYDRUS that have been implemented since 2008. Our review is not limited to listing additional processes that were implemented in the standard computational modules, but also describes many new standard and nonstandard specialized add-on modules that significantly expanded the capabilities of the two software packages. We also review additional capabilities that have been incorporated into the graphical user interface (GUI) that supports the use of HYDRUS (2D/3D). Another objective of this manuscript is to review selected applications of the HYDRUS models such as evaluation of various irrigation schemes, evaluation of the effects of plant water uptake on groundwater recharge, assessing the transport of particle-like substances in the subsurface, and using the models in conjunction with various geophysical methods.Abbreviations: CRS, cosmic-ray sensing; EC, electrical conductivity; ERT, electrical resistivity tomography; FEM, finite element mesh; GPR, ground-penetrating radar; GUI, graphical user interface; TDT, time-domain transmissometry.The HYDRUS-1D and HYDRUS (2D/3D) software packages (Šimůnek et al., 2008b) are finite-element models for simulating the one-and two-or three-dimensional movement of water, heat, and multiple solutes in variably saturated media, respectively. The standard versions, as well as various specialized add-on modules, of the HYDRUS programs numerically solve the Richards equation for saturated-unsaturated water flow and convection-dispersion type equations for heat and solute transport. The flow equation incorporates a sink term to account for water uptake by plant roots as a function of water and salinity stress. Both compensated and uncompensated water uptake by roots can be considered. The heat transport equation considers movement by both conduction and convection with flowing water. The governing convection-dispersion solute transport equations are written in a relatively general form by including provisions for nonlinear, nonequilibrium reactions between the solid and liquid phases and linear equilibrium reactions between the liquid and gaseous phases. The transport models also account for convection and dispersion in the liquid phase as well as diffusion in the gas phase, thus permitting the models to simulate solute transport simultaneously in both the liquid and gaseous phases. Hence, both adsorbed and volatile solutes, such as pesticides and fumigants, can be considered.The solute transport equations further incorporate the effects of zero-order production, first-o...

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Section: Main Modulementioning

confidence: 99%

Recent Developments and Applications of the HYDRUS Computer Software Packages

Šimůnek

Genuchten

Šejna³

2016

Vadose Zone Journal

746

336

View full text Add to dashboard Cite

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“…Equation (14) describes the saturation evolution in the unsaturated part, the saturated flow formula (15) is derived directly from Darcy's flow in the saturated part (at the bottom) and determines the water height table H B (t) in the overflow chamber described by (16), (21) and the amount of expelled water described by (17), (22). Boundary condition (18) is the no-flow condition at r 0 and can be equally written as ∂ r h − ω 2 g r r =r 0 = 0.…”

Section: In Details: Drainage Into An Overflow Cupmentioning

confidence: 99%

“…E.g. [17] use image recognition in the outflow cup. For actual use, the price of a immediately usable centrifuge should not be above 10.000 Euro.…”

Section: Introductionmentioning

confidence: 99%

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Inverse determination of saturated and relative permeability with a bench-scale centrifuge

Kišon

Malengier

Emidio

et al. 2013

Inverse Problems in Science and Engineering

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It is well established that the centrifuge can be an important tool to determine permeabilities of porous materials. Nevertheless, up to this date, for geotechnical applications, they are not used outside research laboratories. We attribute this to the cost of a centrifuge, the apparent requirement of measurements in the sample and the more complicated handling of samples for use in the centrifuge. As a first step towards an affordable centrifuge, we present an adaptation to a common bench-scale centrifuge, which allows to obtain measurements in a fraction of the time needed by standard infiltration methods, especially for clayey soils. The permeabilities are determined by measuring global transient data only: water level in an inflow or outflow chamber and gravitational centre of the sample or the rotational momentum of the sample. These are all measured outside of the centrifuge in a start-stop regime. A method of lines approach to solve the Richards' equation is used, combined with interface tracking, which was previously shown to be an accurate method. Permeabilities are assumed to behave according to the van Genuchten-Mualem formula. We present the experimental set-up, accuracy of the measurements and the numerical solution method. For saturated flow, we compare with standard tests, while for unsaturated flow we compare with a pressure plate result (ASTM D2325). The results indicate the strengths and limitations of this approach, but overall we can conclude that measuring the global characteristics during rotation should provide accurate permeabilities.

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“…K v <1 × 10 −10 m s −1 ) typically consists of applying a confining pressure to a watertight system and measuring small transient pore pressures with high-resolution pressure transducers (API, 1998). Geotechnical centrifuges are used to subject porous samples to high artificial gravities in order to characterise their hydraulic and/or consolidation properties (Conca and Wright, 1998;Nakajima and Stadler, 2006;Znidarčić et al, 2011), and for physical modelling as part of geotechnical design (Garnier et al, 2007;Parks et al, 2012). Accelerated gravity acts on both the solid particles and fluids within the porous sample without use of a large fluid pressure gradient to drive flow.…”

Section: Introductionmentioning

confidence: 99%

Accelerated gravity testing of aquitard core permeability and implications at formation and regional scale

Timms¹,

Crane²,

Anderson³

et al. 2015

Preprint

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Abstract. Evaluating the possibility of leakage through low permeability geological strata is critically important for sustainable water supplies, the extraction of fuels from strata such as coal beds, and the confinement of waste within the earth. The current work demonstrates that relatively rapid and reliable hydraulic conductivity (K) measurement of aquitard cores using accelerated gravity can inform and constrain larger scale assessments of hydraulic connectivity. Steady state fluid velocity through a low K porous sample is linearly related to accelerated gravity (g-level) in a centrifuge permeameter (CP) unless consolidation or geochemical reactions occur. The CP module was custom designed to fit a standard 2 m diameter geotechnical centrifuge (550 g maximum) with a capacity for sample dimensions of 30 to 100 mm diameter and 30 to 200 mm in length, and a maximum total stress of ~2 MPa at the base of the core. Formation fluids were used as influent to limit any shrink–swell phenomena which may alter the permeability. Vertical hydraulic conductivity (Kv) results from CP testing of cores from three sites within the same regional clayey silt formation varied (10−7 to 10−9 m s−1, n = 14). Results at one of these sites (1.1 × 10−10 to 3.5 × 10−9 m s−1, n = 5) that were obtained in < 24 h were similar to in situ Kv values (3 × 10−9 m s−1) from pore pressure responses over several weeks within a 30 m clayey sequence. Core scale and in situ Kv results were compared with vertical connectivity within a regional flow model, and considered in the context of heterogeneity and preferential flow paths at site and formation scale. More reliable assessments of leakage and solute transport though aquitards over multi-decadal timescales can be achieved by accelerated core testing together with advanced geostatistical and numerical methods.

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Centrifuge modeling of one-step outflow tests for unsaturated parameter estimations

Cited by 15 publications

References 33 publications

Recent Developments and Applications of the HYDRUS Computer Software Packages

Recent Developments and Applications of the HYDRUS Computer Software Packages

Inverse determination of saturated and relative permeability with a bench-scale centrifuge

Accelerated gravity testing of aquitard core permeability and implications at formation and regional scale

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