X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Online Resource
    Online Resource
    Hydraulic functions for swelling soils: pore scale considerations
    Elsevier BV ; 2003
    In:  Journal of Hydrology Vol. 272, No. 1-4 ( 2003-3), p. 50-71
    Details
    In: Journal of Hydrology, Elsevier BV, Vol. 272, No. 1-4 ( 2003-3), p. 50-71
    Type of Medium: Online Resource
    ISSN: 0022-1694
    URL: Article
    DOI: 10.1016/S0022-1694(02)00254-8
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2003
    detail.hit.zdb_id: 240687-1
    detail.hit.zdb_id: 1473173-3
    SSG: 13
    SSG: 14
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 2
    Online Resource
    Online Resource
    Hydraulic conductivity of partially saturated fractured porous media: flow in a cross-section
    Elsevier BV ; 2003
    In:  Advances in Water Resources Vol. 26, No. 8 ( 2003-8), p. 883-898
    Details
    In: Advances in Water Resources, Elsevier BV, Vol. 26, No. 8 ( 2003-8), p. 883-898
    Type of Medium: Online Resource
    ISSN: 0309-1708
    URL: Article
    DOI: 10.1016/S0309-1708(03)00051-4
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2003
    detail.hit.zdb_id: 2023320-6
    detail.hit.zdb_id: 428761-7
    SSG: 14
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 3
    Online Resource
    Online Resource
    Liquid retention and interfacial area in variably saturated porous media: Upscaling from single‐pore to sample‐scale model
    American Geophysical Union (AGU) ; 1999
    In:  Water Resources Research Vol. 35, No. 12 ( 1999-12), p. 3591-3605
    Details
    In: Water Resources Research, American Geophysical Union (AGU), Vol. 35, No. 12 ( 1999-12), p. 3591-3605
    Abstract: A new model for liquid configuration in angular pore space considering both capillary and adsorptive contributions was proposed as an alternative to the conventional bundle of capillaries representation. In this study we develop a statistical framework for upscaling pore‐scale processes to represent a sample‐scale response of variably saturated porous medium. The representation of pore size distribution by the gamma distribution enables derivation of closed‐form expressions for sample‐scale liquid retention and liquid‐vapor interfacial area. The statistical framework calculates the expected values of liquid configuration as a function of pore geometry and chemical potential considerations. Media properties are used to estimate upscaling parameters by matching model predictions with measured retention data subject to specific surface area constraint. Additionally, a method for estimating liquid‐solid adsorption behavior for the medium is proposed. Model predictions compare favorably with measured retention data, yielding a similar close fit as obtained with the van Genuchten parametric model. Liquid‐vapor interfacial area as a function of chemical potential is readily calculated using the estimated retention parameters. Model calculations of liquid‐vapor interfacial area for sand show reasonable agreement with measurements obtained with surface‐active tracers. The contribution of liquid films dominates the total liquid‐vapor interfacial area and often surpasses the capillary contribution (curved menisci) by several orders of magnitude. This illustrates potential limitations in using cylindrical pore network modeling of interfacial area for multiphase flow predictions. The detailed picture of liquid vapor interfaces provides a sound basis for unsaturated hydraulic conductivity calculations in the sample cross section (i.e., neglecting network effects) and offers insights into microbial habitats and related exchange processes in partially saturated porous media.
    Type of Medium: Online Resource
    ISSN: 0043-1397 , 1944-7973
    URL: Article
    DOI: 10.1029/1999WR900262
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1999
    detail.hit.zdb_id: 2029553-4
    detail.hit.zdb_id: 5564-5
    SSG: 13
    SSG: 14
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 4
    Online Resource
    Online Resource
    Measurements and Modeling of Variable Gravity Effects on Water Distribution and Flow in Unsaturated Porous Media
    Wiley ; 2007
    In:  Vadose Zone Journal Vol. 6, No. 4 ( 2007-11), p. 713-724
    Details
    In: Vadose Zone Journal, Wiley, Vol. 6, No. 4 ( 2007-11), p. 713-724
    Abstract: Liquid behavior under reduced gravity conditions is of considerable interest for various components of life‐support systems required for manned space missions. High costs and limited opportunities for spaceflight experiments hinder advances in reliable design and operation of elements involving fluids in unsaturated porous media such as plant growth facilities. We used parabolic flight experiments to characterize hydraulic properties under variable gravity conditions deduced from variations in matric potential over a range of water contents. We designed and tested novel measurement cells that allowed dynamic control of water content. Embedded time domain reflectometry probes and fast‐responding tensiometers measured changes in water content and matric potential. For near‐saturated conditions, we observed rapid establishment of equilibrium matric potentials during the recurring 20‐s periods of microgravity. As media water content decreased, the concurrent decrease in hydraulic diffusivity resulted in limited attainment of equilibrium distributions of water content and matric potential in microgravity, and water content heterogeneity within the sample was influenced by the preceding hypergravity phase. For steady fluxes through saturated columns, we observed linear and constant hydraulic gradients during variable gravity, yielding saturated hydraulic conductivities similar to values measured under terrestrial gravity. Our results suggest that water distribution and retention behavior are sensitive to varied gravitational forces, whereas saturated hydraulic conductivity appears to be unaffected. Comparisons between measurements and simulations based on the Richards equation were in reasonable agreement, suggesting that fundamental laws of fluid flow and distribution for macroscopic transport derived on Earth are also applicable in microgravity.
    Type of Medium: Online Resource
    ISSN: 1539-1663 , 1539-1663
    URL: Article
    DOI: 10.2136/vzj2006.0105
    Language: English
    Publisher: Wiley
    Publication Date: 2007
    detail.hit.zdb_id: 2088189-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 5
    Online Resource
    Online Resource
    Unsaturated Hydraulic Conductivity of Structured Porous Media
    Wiley ; 2002
    In:  Vadose Zone Journal Vol. 1, No. 1 ( 2002), p. 14-
    Details
    In: Vadose Zone Journal, Wiley, Vol. 1, No. 1 ( 2002), p. 14-
    Type of Medium: Online Resource
    ISSN: 1539-1663
    URL: Article
    DOI: 10.2136/vzj2002.0014
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 2088189-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 6
    Online Resource
    Online Resource
    Unsaturated Hydraulic Conductivity of Structured Porous Media: A Review of Liquid Configuration–Based Models
    Wiley ; 2002
    In:  Vadose Zone Journal Vol. 1, No. 1 ( 2002-08), p. 14-37
    Details
    In: Vadose Zone Journal, Wiley, Vol. 1, No. 1 ( 2002-08), p. 14-37
    Abstract: Common approaches for modeling hydraulic functions of unsaturated structured porous media (SPM) rely on macroscopic continuum representation, where parameterization schemes and constitutive relationships originally developed for homogeneous porous media are extended to represent hydraulic behavior of dual (or multi) continuum SPM. Such models often result in inconsistencies due to lack of consideration of structural pore space geometry and the neglect of underlying physical processes governing liquid retention and flow under unsaturated conditions. We review a new framework that considers equilibrium liquid configurations in dual continuum pore space as the basis for calculation of liquid saturation and subsequent introduction of hydrodynamic considerations. The SPM pore space is represented by a bimodal distribution of pore sizes, reflecting two disparate populations of matrix and structural pores. Three steady‐state and laminar flow regimes are considered to derive unsaturated hydraulic conductivity functions: (i) flow in completely filled pore spaces, (ii) corner flow in partially filled pores and grooves, and (iii) film flow on solid surfaces. Two key assumptions are used in deriving the average cross‐sectional flow velocities in these regimes: (i) that equilibrium liquid–vapor interfaces remain stable under slow laminar flows and (ii) that flow pathways are parallel. Liquid–vapor interfacial configurations for different matric potentials are calculated and statistically upscaled to derive sample‐scale saturated and unsaturated hydraulic conductivity from velocity expressions weighted by the appropriate liquid‐occupied cross‐sectional areas, neglecting three‐dimensional (3‐D) network effects. Similarly, the hydraulic functions for matrix and structural pores are derived separately and later combined by weighting the individual contributions by the porosities of the associated pore spaces. A parameter estimation scheme was developed to calculate liquid saturation and to predict sample‐scale unsaturated hydraulic conductivity. Model evaluation using measured data for homogeneous porous media, fractured welded tuff, and macroporous and aggregated soils shows favorable agreement (within the limitations of model assumptions). Effects of nonequilibrium conditions between matrix and structural pore domains on the hydraulic conductivity and approximate consideration of 3‐D network effects are discussed.
    Type of Medium: Online Resource
    ISSN: 1539-1663 , 1539-1663
    URL: Article
    DOI: 10.2136/vzj2002.1400
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 2088189-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 7
    Online Resource
    Online Resource
    Flow in unsaturated fractured porous media: Hydraulic conductivity of rough surfaces
    American Geophysical Union (AGU) ; 2000
    In:  Water Resources Research Vol. 36, No. 5 ( 2000-05), p. 1165-1177
    Details
    In: Water Resources Research, American Geophysical Union (AGU), Vol. 36, No. 5 ( 2000-05), p. 1165-1177
    Abstract: The general trend in models for flow in unsaturated fractured porous media is to regard desaturated fractures as nonparticipating elements that impede flow. Mounting experimental and theoretical evidence shows that fractures retain and conduct liquid in the form of film and partially filled corner flow to a relatively low degree of saturation. A simple geometrical model for rough fracture surfaces is developed offering a tractable geometry for calculations of surface liquid storage due to adsorbed films and capillary menisci. Assuming that under slow laminar flow the equilibrium liquid configurations on the fracture surface are not modified significantly, the average hydraulic conductivities for film and corner flows were derived and used as building blocks for a representative fracture roughness element and an assemblage of statistically distributed surface roughness elements. Calculations for a single representative element yielded excellent agreement with surface storage and unsaturated hydraulic conductivity measurements of Tokunaga and Wan [1997]. A statistical representation of surface roughness using a gamma distribution of pit depths resulted in closed‐form expressions for unsaturated hydraulic conductivity averaged across the fracture length (transverse to flow) or weighted by the liquid cross section occupying the fracture surface. An important attribute of the surface roughness model is the direct link between fracture surface and matrix processes unified by the matric potential. The proposed model represents a first step toward development of a comprehensive approach for liquid retention and hydraulic conductivity of unsaturated fractured porous media based on details of liquid configuration for different matric potentials.
    Type of Medium: Online Resource
    ISSN: 0043-1397 , 1944-7973
    URL: Article
    DOI: 10.1029/2000WR900020
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2000
    detail.hit.zdb_id: 2029553-4
    detail.hit.zdb_id: 5564-5
    SSG: 13
    SSG: 14
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 8
    Online Resource
    Online Resource
    Adsorption and capillary condensation in porous media: Liquid retention and interfacial configurations in angular pores
    American Geophysical Union (AGU) ; 1999
    In:  Water Resources Research Vol. 35, No. 7 ( 1999-07), p. 1949-1964
    Details
    In: Water Resources Research, American Geophysical Union (AGU), Vol. 35, No. 7 ( 1999-07), p. 1949-1964
    Abstract: Conventional models of liquid distribution, flow, and solute transport in partially saturated porous media are limited by the representation of media pore space as a bundle of cylindrical capillaries (BCC). Moreover, the capillary model ignores the dominant contribution of adsorptive surface forces and liquid films at low potentials. We propose two new complementary elements for improving our understanding of liquid configuration in porous media: (1) an approach for considering the individual contributions of adsorptive and capillary forces to the matric potential and (2) a more realistic model for pore space geometry. Modern interface science formalism is applied to determine the thickness of adsorbed liquid films as a function of thermodynamic conditions and specific surface area of the medium. The augmented Young‐Laplace (AYL) equation provided the necessary framework for combining adsorptive and capillary processes. A new pore space geometry composed of an angular pore cross section (for capillary processes) connected to slit‐shaped spaces with internal surface area (for adsorption processes) offers a more realistic representation of natural porous media with explicit consideration of surface area (absent in the standard BCC model). Liquid‐vapor configuration, saturation, and liquid‐vapor interfacial area were calculated for different potentials and pore (unit cell) dimensions. Pore dimensions may be easily related to measurable soil properties such as specific surface area and porosity. Rigorous calculations based on the AYL equation were simplified and led to the development of algebraic expressions relating saturation and interfacial area of liquid in the proposed pore space geometry to chemical potential. These simple expressions are amenable to upscaling procedures similar to those presently used with the BCC model.
    Type of Medium: Online Resource
    ISSN: 0043-1397 , 1944-7973
    URL: Article
    DOI: 10.1029/1999WR900098
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 1999
    detail.hit.zdb_id: 2029553-4
    detail.hit.zdb_id: 5564-5
    SSG: 13
    SSG: 14
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 9
    Online Resource
    Online Resource
    Cavitation during desaturation of porous media under tension : TECHNICAL NOTE
    American Geophysical Union (AGU) ; 2002
    In:  Water Resources Research Vol. 38, No. 5 ( 2002-05), p. 19-1-19-14
    Details
    In: Water Resources Research, American Geophysical Union (AGU), Vol. 38, No. 5 ( 2002-05), p. 19-1-19-14
    Type of Medium: Online Resource
    ISSN: 0043-1397
    URL: Article
    DOI: 10.1029/2001WR000282
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2002
    detail.hit.zdb_id: 2029553-4
    detail.hit.zdb_id: 5564-5
    SSG: 13
    SSG: 14
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
  • 10
    Online Resource
    Online Resource
    Water films and scaling of soil characteristic curves at low water contents : SCALING OF CHARACTERISTIC CURVES
    American Geophysical Union (AGU) ; 2005
    In:  Water Resources Research Vol. 41, No. 9 ( 2005-09)
    Details
    In: Water Resources Research, American Geophysical Union (AGU), Vol. 41, No. 9 ( 2005-09)
    Type of Medium: Online Resource
    ISSN: 0043-1397
    URL: Article
    DOI: 10.1029/2005WR004142
    Language: English
    Publisher: American Geophysical Union (AGU)
    Publication Date: 2005
    detail.hit.zdb_id: 2029553-4
    detail.hit.zdb_id: 5564-5
    SSG: 13
    SSG: 14
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Open Access Request
    Availability (electronic / print)
Nothing or not found what you are looking for? Please check your search query or use the Interlibrary Loan Search.
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages