6,334 Works

Numerical Evaluation and Interpretation of Measured Effective Dielectric Permittivities during Two Phase Flow in a Porous Medium

Willem-Jan Plug, Johannes Bruining, Evert Slob, Ainhoa Gorriti & Willem-Jan Plug
An experimental procedure is presented where the capillary pressure and the dielectric properties of a porous medium can be measured simultaneously. Our objective is to determine a consistent relationship between capillary pressure versus water saturation and its effect on the effective frequency dependent dielectric permittivity. Applications are found in in-situ subsurface measurements like Ground Penetrating Radar, borehole measurements and logging tools. We have built an experimental set up that can measure capillary pressure under various...

Two fuzzy and optimal models of water resources evaluation based on the Principle of Maximum Entropy (POME) and Engineering Fuzzy Set Theory

WANG Dong & WANG Dong
The randomness of characteristic value of water resources evaluation is inevitable during its monitoring, experimenting, and data analyzing, as a result of the physical process, the chemical process and biological process of water contamination are all stochastic process. On the other hand, the fuzziness of water resources evaluation is also inevitable, for the classification standard, the evaluation class and pollution degree is impersonal fuzzy concept and phenomenon. Entropy is a very important scientific conception. The...

Period characteristics of representative hydrologic series in the Yellow River in China using maximum entropy spectra analysis(MESA)

WANG Dong & WANG Dong
In the field of stochastic hydrology, hydrologic series is formed with the non- periodic component, the periodic component and the stochastic component. Here the period characteristics used include approximate periods in the non-periodic component, simple periods and complex periods in the periodic component. Spectral analysis is an essential and effective tool for extracting such stochastic characteristics of time series. In 1948, Shannon developed a mathematical theory of entropy and applied it in communications. Nearly a...

Connectivity of fracture networks: The effects of anisotropy and spatial correlation

Mohsen Masihi, Peter R King, Peyman Nurafza & Mohsen Masihi
In fractured formations of very low matrix permeability connectivity of fractures is a crucial parameter which may have a significant impact on the overall flow. The connectivity behaviour of fracture networks can be analysed by using percolation theory. The scaling law within this theory is used to predict the connectivity and its associated uncertainty very rapidly. Although the effects of some geometrical parameters of fractures (e.g. size distribution) on the universal connectivity curves are extensively...

Connectivity of fracture networks: The effects of anisotropy and spatial correlation

Mohsen Masihi, Peter R King, Peyman Nurafza & Mohsen Masihi
In fractured formations of very low matrix permeability connectivity of fractures is a crucial parameter which may have a significant impact on the overall flow. The connectivity behaviour of fracture networks can be analysed by using percolation theory. The scaling law within this theory is used to predict the connectivity and its associated uncertainty very rapidly. Although the effects of some geometrical parameters of fractures (e.g. size distribution) on the universal connectivity curves are extensively...

ESTIMATING SURFACE FLUXES IN IRRIGATED AREAS WITH SCINTILLOMETERS

Oscar Hartogensis, Henk De Bruin & Oscar Hartogensis
Scintillometry has proven to be a good alternative method to obtain surface fluxes over heterogeneous areas over spatial scales of up to 10 km and in non-stationary conditions in the stable surface layer (see e.g. [1]). This study concerns agro- hydrological scintillometer applications of estimating evaporation over homogeneous irrigated areas on a scale of 50 to 500 m. Two types of scintillometers will be considered, notably the displaced beam small aperture scintillometer (DBSAS) and the...

An Integrated Media, Integrated Processes Watershed Model – WASH123D: Part 5 – Integrated modeling of surface water and groundwater interactions in a constructed wetland

GUOBIAO HUANG, Gour-Tsyh Yeh & Gour-Tsyh Yeh
A pilot constructed wetland in south Florida, USA, the Everglades Nutrient Removal (ENR) project was modeled with a physics-based integrated approach by WASH123D. Stormwater is routed into the treatment wetland for phosphorus removal by plant and sediment intake. It overlies a highly permeable surficial groundwater aquifer. Strong surface water and groundwater interactions are a key component of the hydrologic processes. The site has extensive field measurement and monitoring that provide point scale and distributed data...

An Integrated Media, Integrated Processes Watershed Model – WASH123D: Part 5 – Integrated modeling of surface water and groundwater interactions in a constructed wetland

GUOBIAO HUANG, Gour-Tsyh Yeh & Gour-Tsyh Yeh
A pilot constructed wetland in south Florida, USA, the Everglades Nutrient Removal (ENR) project was modeled with a physics-based integrated approach by WASH123D. Stormwater is routed into the treatment wetland for phosphorus removal by plant and sediment intake. It overlies a highly permeable surficial groundwater aquifer. Strong surface water and groundwater interactions are a key component of the hydrologic processes. The site has extensive field measurement and monitoring that provide point scale and distributed data...

Volume of Fluid Simulations of Multiphase Flow through Fractures: Analysis of Individual Fractures for Application in Reservoir Scale Models

Dustin Crandall, Kambiz Nazridoust, Goodarz Ahmadi, Grant Bromhal, Duane Smith & Duane Smith
Geological Carbon Dioxide Sequestration requires a fundamental understanding of modeling multiphase flows in fractured media. Subsurface flow is highly dependent upon the rock structure within the flow domain, with high permeability and fractured regions dominating the transport of the fluids. Discrete-fracture simulators often assume the cubic law relationship for single phase flow through a smooth set of parallel plates, and with good reason. The number of fractures that need to be modeled at the reservoir...

WELL CATCHMENTS ESTIMATION IN HETEROGENEOUS AQUIFERS WITH A STRATIFIED MODEL

Paolo Salandin, Filomena Savini, Gianluca Marconi & Gianluca Marconi
A new method is proposed to delimitate wellhead protection areas in a confined aquifer where hydraulic conductivity is assumed as spatially random function. In a natural formation the heterogeneity of porous media influences the capture zone delimitation and considerable differences can result from the homogenous case. In the last decade several approaches were proposed to solve the problem but they need of a priori description of statistical properties of aquifer that are usually unknown or...

Scale Dependent Fluid Momentum and Solute Mass Macroscopic Balance Equations: Theory and Observations

Shaul Sorek, Daniel Ronen & Shaul Sorek
A mathematical development is presented concerning extensions to the macroscopic momentum balance equation for compressible Newtonian fluids flowing through saturated porous matrices, and the macroscopic mass balance equation of solutes transported with the fluids. It is shown that each of these balance equations is composed of a dominant macroscopic equation associated with a larger spatial scale, coupled with a secondary macroscopic balance equation valid at a smaller spatial scale. The dominant fluid momentum balance equation...

Darcy multi-domain approach for integrated surface/subsurface hydrologic models

Sylvain WEILL, Emmanuel MOUCHE & Sylvain WEILL
A Darcy multi-domain approach for modeling surface and subsurface hydrologic processes is presented. The diffusive wave approximation is used to model runoff. The resulting equation is formulated as a Darcy nonlinear one. Therefore, the water dynamics in the three physical domains, ground surface, vadose zone and saturated zone, is described through a single Darcy nonlinear equation with domain-dependent parameters. This multi-domain Darcy equation is solved with Mixed Hybrid Finite Element formulation. The time discretisation is...

Darcy multi-domain approach for integrated surface/subsurface hydrologic models

Sylvain WEILL, Emmanuel MOUCHE & Sylvain WEILL
A Darcy multi-domain approach for modeling surface and subsurface hydrologic processes is presented. The diffusive wave approximation is used to model runoff. The resulting equation is formulated as a Darcy nonlinear one. Therefore, the water dynamics in the three physical domains, ground surface, vadose zone and saturated zone, is described through a single Darcy nonlinear equation with domain-dependent parameters. This multi-domain Darcy equation is solved with Mixed Hybrid Finite Element formulation. The time discretisation is...

Drainage with Unfavorable Viscosity Ratios: a pore-level model study

Martin Ferer, Grant Bromhal, Duane Smith & Martin Ferer
The applications of carbon dioxide sequestration in brine-saturated reservoirs, as well as recovery of oil from oil-wet reservoirs, involve the injection of a less- viscous, non-wetting fluid into a porous medium occupied by a more-viscous, wetting fluid: i.e., drainage with an unfavorable viscosity ratio. In these cases, there is a competition between capillary fingering and viscous fingering. In standard treatments of two-phase flow in porous media, the flow is assumed to be compact, with a...

Chemistry-Transport coupling : Implicit schemes keeping a code coupling approach

Raphaèle Herbin, Philippe Montarnal, Nicolas Bouillard & Nicolas Bouillard
This work is linked with the field of reactive transport simulations in the context of reactive waste storage in deep geological disposals. Indeed, the evolution of the different materials and the species migration are deeply influenced by chemical, hydraulic and transport interactions. For these modeling issues it is necessary to deal with numerical codes involving combined effect of transport and multiple geochemical species within groundwater flow. Currently, many of the codes use a sequential iterative...

Monitoring unsaturated flow and transport using cross-borehole geophysical methods

Majken C Looms, Karsten H Jensen, Lars Nielsen, Andrew Binley, Hans Thybo & Majken C Looms
Recent research has shown that cross-borehole georadar and electrical resistivity tomography (ERT) can provide data on soil moisture content and conductivity variations in the vadose zone at a more appropriate spatial scale than traditional techniques. A field site has been established in Denmark on a 20-30 m layer of unsaturated melt water sand and gravel deposits. Two identical field setups have been established each having four ERT and four georadar boreholes. The boreholes are drilled...

Streamline methods on fault adapted grids for risk assessment of storage of CO2 in geological formations

Håkon Hægland, Helge Dahle, Geir Terje Eigestad, Michael Celia, Jan Martin Nordbotten, Erlend Øian & Håkon Hægland
Streamline methods have shown to be effective for reservoir characterization and simulation. In this work we will develop methodology which allows for tracing of streamlines in fractured or faulted media including anthropogenic faults such as abandoned wells. The basis for a streamline method is a sequential splitting of the coupled pressure and saturation equations. A mass-conservative discretization, which handles general faulted grids in a consistent manner, will be used for the pressure equation. The fact...

BGK Boltzmann Model and Lattice Boltzmann Method for Shallow Water Flows

Junhong LIANG, Mohamed GHIDAOUI & Junhong LIANG
Both the Bhatnagar-Gross-Krook (BGK) Boltzmann model and Lattice Boltzmann method (LBM) are based on the numerical discretization of the Boltzmann equation with collisional models, such as, the BGK model. The BGK Boltzmann scheme is a finite volume scheme, where the time-dependent distribution function with continuous particle velocity space is constructed and used in the evaluation of the numerical fluxes across cell interfaces. On the other hand, LBM tracks limited number of particles and the viscous...

APPLICATION OF ACO ALGORITHM IN SCS-CN METHOD

Mortazavi Naeini Seyed Mohammad, P. Suresh Babu & Mortazavi Naeini Seyed Mohammad
Calibrating the most appropriate parameter is one of the crucial stages in dependable rainfall-runoff modeling. This paper evaluates the computational performance of Ant Colony Optimization (ACO) and Marquardt Algorithms (MA) used for calibration of CN and λ parameters of the Soil Conservation Service Curve Number (SCS-CN) model in optimization. Employing standard error of estimate (Se) and standard error ratio (SER), the performance of both the algorithms was tested on a large set of US data.

Parallelization of the WASH123D Code—Phase III: 1-Dimensional Channel, 2-Dimensional Overland, and 3-Dimensional Subsurface Flows

Jing-Ru Cheng Cheng, Robert Hunter, Hwai-Ping Cheng, David Richards & Jing-Ru Cheng Cheng
Watershed models are used to simulate and predict major hydrological processes, such as surface or subsurface flows, which may occur on different spatial domains and temporal scales. A key feature of watershed models is the ability to model interactions among different processes and domains. Such interactions can be strongly or weakly coupled depending on the relevant time scales for each process. WASH123D is a first-principles, physics-based model for simulating a coupled system of channel flow,...

Discontinous Galerkin Methods for the Sahllow-Water Equations with bathymetric terms and dry areas

Karim DJADEL, Alexandre ERN, Serge PIPERNO & Karim DJADEL
In this paper, we develop Discontinuous Galerkin Methods to deal with the Shallow-Water Equations involving bathymetric temrms and dry areas. Our major goals are on the one hand to preserve quiescent flows and, more generally, steady-states and on the other hand to ensure stability when the flow includes flooding and drying. Drawing on earlier ideas for Finite Volume Methods [Aud,Ber], we design two Discontinuous Galerkin Methods that preserve flows at rest. We investigate their acuracy...

Application of Ant Algorithm in Calibration of Rainfall-Runoff Model

Mortazavi Naeini Seyed Mohammad, Alireza B.Dariane & Mortazavi Naeini Seyed Mohammad
The successful application of a conceptual rainfall-runoff (CRR) model depends on how it is calibrated. The CRR models generally represent the soil moisture accounting phase of the hydrologic cycle as several interconnected subsystems, each representing a certain component in the processing of the hydrologic event. Despite the popularity of CRR models, reports in the literature indicate that difficulties in calibrating the parameters. Ant Colony Optimization (ACO) is one of the recent optimization methods which is...

Pore network modeling of convective drying

Andreas Yiotis, Ioannis Tsimpanogiannis, Athanassios Stubos, Yanis Yortsos & Andreas Yiotis
Drying of porous media is a process of significant scientific and applied interest. It involves several mechanisms at the pore scale that affect the macroscopic behavior of the drying process. These include phase change at the liquid-gas interface, mass and heat transfer by diffusion and convection, capillarity-induced flow through wetting liquid films and the receding of the liquid gas interfaces under combined viscous, capillary and buoyancy forces. In most typical applications, porous materials are subjected...

A structural approach to joint inversion of hydrogeophysical data

Niklas Linde, Andrew Binley, Ari Tryggvason, Laust Pedersen & Niklas Linde
We have developed a flexible methodology to jointly invert different types of geophysical and hydrogeological data, where the resulting models honour the spatial correlation structure derived from geophysical borehole logs. Additionally, the individual models are internally consistent. The key components in this work are: (1) an efficient method to estimate stochastic regularization operators based on geostatistical models; (2) to minimize the cross product of the gradients of two models, which is used as a measure...

Reconstruction of the three-dimensional Darcy velocity in a small catchment using self-potential, electrical resistivity, and induced polarization data

Niklas Linde, André Revil, Barbara Suski, Cécile Dagès, Marc Voltz & Niklas Linde
One of the ultimate goals of hydrogeophysics is to map the groundwater table throughout a catchment and together with information about hydrogeological properties of the saturated zone, derived from geophysical and hydrogeological data, estimate the Darcy velocity in three dimensions throughout the saturated zone. In this work, we present our first attempts to achieve this goal in the small (~1 km2) catchment area of Roujan (Hérault, France), which is a well characterized hydrogeological research site....

Registration Year

  • 2021
    33
  • 2020
    499
  • 2019
    1,120
  • 2018
    80
  • 2017
    28
  • 2016
    4
  • 2015
    8
  • 2014
    518
  • 2013
    2
  • 2011
    4,040

Resource Types

  • Text
    4,763
  • Event
    746
  • Dataset
    521
  • Audiovisual
    116
  • Software
    56
  • Other
    54
  • Collection
    48
  • Image
    30

Affiliations

  • Technical University of Denmark
    55
  • Aarhus University
    4
  • Aalborg University
    4
  • Denmark Technical College
    2
  • University of Southern Denmark
    2