Search NASA⌕ Search

SEARCH · Search NASA

Results for “Pressure space”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on AsH5C2(OF3)2 by Materials Project

C2AsH5(OF3)2 is High Pressure (4-7GPa) Tellurium-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four C2AsH5(OF3)2 clusters. there are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a tetrahedral geometry to three H1+ and one O2- atom. All C–H bond lengths are 1.09 Å. The C–O bond length is 1.48 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.09 Å. Both C–O bond lengths are 1.28 Å. As3- is bonded in an octahedral geometry to six F1- atoms. There are a spread of As–F bond distances ranging from 1.76–1.83 Å. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the third H1+ site, H1+ is bonded in a linear geometry to one O2- and one F1- atom. The H–O bond length is 1.02 Å. The H–F bond length is 1.51 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one C4+ and one H1+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two C4+ atoms. There are six inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one As3- atom. In the second F1- site, F1- is bonded in a single-bond geometry to one As3- atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As3- atom. In the fourth F1- site, F1- is bonded in a bent 120 degrees geometry to one As3- and one H1+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one As3- atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to one As3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on P2SN3Cl5O by Materials Project

P2N3SOCl5 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four P2N3SOCl5 clusters. there are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to two N+0.33- and two Cl1- atoms to form PN2Cl2 tetrahedra that share a cornercorner with one PN2Cl2 tetrahedra and a cornercorner with one SN2ClO tetrahedra. There is one shorter (1.59 Å) and one longer (1.62 Å) P–N bond length. There are one shorter (1.99 Å) and one longer (2.01 Å) P–Cl bond lengths. In the second P5+ site, P5+ is bonded to two N+0.33- and two Cl1- atoms to form PN2Cl2 tetrahedra that share a cornercorner with one PN2Cl2 tetrahedra and a cornercorner with one SN2ClO tetrahedra. There is one shorter (1.59 Å) and one longer (1.62 Å) P–N bond length. Both P–Cl bond lengths are 2.00 Å. There are three inequivalent N+0.33- sites. In the first N+0.33- site, N+0.33- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the second N+0.33- site, N+0.33- is bonded in a bent 120 degrees geometry to one P5+ and one S2- atom. The N–S bond length is 1.57 Å. In the third N+0.33- site, N+0.33- is bonded in a bent 120 degrees geometry to one P5+ and one S2- atom. The N–S bond length is 1.57 Å. S2- is bonded to two N+0.33-, one O2-, and one Cl1- atom to form distorted SN2ClO tetrahedra that share corners with two PN2Cl2 tetrahedra. The S–O bond length is 1.43 Å. The S–Cl bond length is 2.09 Å. O2- is bonded in a single-bond geometry to one S2- atom. There are five inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one S2- atom. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom. In the fifth Cl1- site, Cl1- is bonded in a single-bond geometry to one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AsS by Materials Project

SAs is High Pressure (4-7GPa) Tellurium-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four SAs clusters. there are four inequivalent As2+ sites. In the first As2+ site, As2+ is bonded in a distorted trigonal non-coplanar geometry to three S2- atoms. There are a spread of As–S bond distances ranging from 2.28–2.30 Å. In the second As2+ site, As2+ is bonded in a water-like geometry to two S2- atoms. There are one shorter (2.27 Å) and one longer (2.30 Å) As–S bond lengths. In the third As2+ site, As2+ is bonded in a single-bond geometry to one S2- atom. The As–S bond length is 2.22 Å. In the fourth As2+ site, As2+ is bonded in a water-like geometry to two S2- atoms. There are one shorter (2.27 Å) and one longer (2.30 Å) As–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded in an L-shaped geometry to two As2+ atoms. In the second S2- site, S2- is bonded in a water-like geometry to two As2+ atoms. In the third S2- site, S2- is bonded in a water-like geometry to two As2+ atoms. In the fourth S2- site, S2- is bonded in a water-like geometry to two As2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on As2Cl3OF5 by Materials Project

As2OCl3F5 is High Pressure (4-7GPa) Tellurium-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four As2OCl3F5 clusters. there are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to one O2- and five F1- atoms to form corner-sharing AsOF5 octahedra. The As–O bond length is 1.93 Å. There are a spread of As–F bond distances ranging from 1.76–1.78 Å. In the second As5+ site, As5+ is bonded to one O2- and three Cl1- atoms to form corner-sharing AsCl3O tetrahedra. The corner-sharing octahedral tilt angles are 53°. The As–O bond length is 1.70 Å. There are one shorter (2.10 Å) and two longer (2.11 Å) As–Cl bond lengths. O2- is bonded in a distorted bent 120 degrees geometry to two As5+ atoms. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one As5+ atom. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one As5+ atom. In the third Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one As5+ atom. There are five inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SbCNCl4O by Materials Project

CSbNOCl4 is High Pressure (4-7GPa) Tellurium-like structured and crystallizes in the hexagonal P6_3/m space group. The structure is zero-dimensional and consists of two CSbNOCl4 clusters. C4+ is bonded in a trigonal planar geometry to two equivalent N3- and one O2- atom. There is one shorter (1.34 Å) and one longer (1.37 Å) C–N bond length. The C–O bond length is 1.28 Å. Sb5+ is bonded in an octahedral geometry to one N3-, one O2-, and four Cl1- atoms. The Sb–N bond length is 2.30 Å. The Sb–O bond length is 2.21 Å. There are a spread of Sb–Cl bond distances ranging from 2.33–2.36 Å. N3- is bonded in a 3-coordinate geometry to two equivalent C4+ and one Sb5+ atom. O2- is bonded in a distorted L-shaped geometry to one C4+ and one Sb5+ atom. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Sb5+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Sb5+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Sb5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na by Materials Project

Na is High pressure (38.9 GPa) phase of lithium structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Na is bonded in a 11-coordinate geometry to eleven equivalent Na atoms. There are a spread of Na–Na bond distances ranging from 3.63–3.78 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs by Materials Project

Cs is High Pressure (4-7GPa) Tellurium-like structured and crystallizes in the tetragonal P4_2/mbc space group. The structure is three-dimensional. Cs is bonded in a 6-coordinate geometry to six equivalent Cs atoms. There are a spread of Cs–Cs bond distances ranging from 5.15–5.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NClO3 by Materials Project

ClONO2 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four chlorine nitrate molecules. N is bonded in a trigonal planar geometry to three O atoms. There are a spread of N–O bond distances ranging from 1.20–1.54 Å. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one N atom. In the second O site, O is bonded in a bent 120 degrees geometry to one N and one Cl atom. The O–Cl bond length is 1.68 Å. In the third O site, O is bonded in a single-bond geometry to one N atom. Cl is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PbS by Materials Project

PbS is High Pressure (4-7GPa) Tellurium-derived structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Pb2+ is bonded to six equivalent S2- atoms to form a mixture of edge, face, and corner-sharing PbS6 octahedra. The corner-sharing octahedral tilt angles are 47°. There are three shorter (2.84 Å) and three longer (3.31 Å) Pb–S bond lengths. S2- is bonded in a 6-coordinate geometry to six equivalent Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaMoP2 by Materials Project

BaMoP2 is High Pressure (4-7GPa) Tellurium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ba2+ is bonded in a 6-coordinate geometry to six equivalent P3- atoms. All Ba–P bond lengths are 3.19 Å. Mo4+ is bonded in a 6-coordinate geometry to six equivalent P3- atoms. All Mo–P bond lengths are 2.52 Å. P3- is bonded in a 6-coordinate geometry to three equivalent Ba2+ and three equivalent Mo4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrS2O13 by Materials Project

ZrS2O13 is High Pressure (4-7GPa) Tellurium-like structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one ZrS2O13 cluster. Zr is bonded to seven O atoms to form distorted ZrO7 pentagonal bipyramids that share corners with two equivalent SO4 tetrahedra and an edgeedge with one SO4 tetrahedra. There are a spread of Zr–O bond distances ranging from 2.01–2.42 Å. There are two inequivalent S sites. In the first S site, S is bonded to four O atoms to form SO4 tetrahedra that share an edgeedge with one ZrO7 pentagonal bipyramid. There are a spread of S–O bond distances ranging from 1.45–1.55 Å. In the second S site, S is bonded to four O atoms to form SO4 tetrahedra that share corners with two equivalent ZrO7 pentagonal bipyramids. There are a spread of S–O bond distances ranging from 1.46–1.52 Å. There are thirteen inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one S atom. In the second O site, O is bonded in a single-bond geometry to one S atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Zr and one S atom. In the fourth O site, O is bonded in a bent 150 degrees geometry to one Zr and one S atom. In the fifth O site, O is bonded in a single-bond geometry to one Zr atom. In the sixth O site, O is bonded in a distorted L-shaped geometry to one Zr and one S atom. In the seventh O site, O is bonded in a single-bond geometry to one S atom. In the eighth O site, O is bonded in a water-like geometry to one Zr and one S atom. In the ninth O site, O is bonded in a single-bond geometry to one S atom. In the tenth O site, O is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.25 Å) and one longer (1.33 Å) O–O bond length. In the eleventh O site, O is bonded in a single-bond geometry to one Zr atom. In the twelfth O site, O is bonded in a bent 120 degrees geometry to one Zr and one O atom. In the thirteenth O site, O is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HgBrCl by Materials Project

HgClBr is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four bromo(chloro)mercury molecules. Hg2+ is bonded in a 2-coordinate geometry to one Br1- and one Cl1- atom. The Hg–Br bond length is 2.46 Å. The Hg–Cl bond length is 2.35 Å. Br1- is bonded in a distorted single-bond geometry to one Hg2+ atom. Cl1- is bonded in a distorted single-bond geometry to one Hg2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B2H8N by Materials Project

B3H8B(NH4)2 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four B(NH4)2 clusters and four B3H8 clusters. In each B(NH4)2 cluster, B3- is bonded in a tetrahedral geometry to two N2- and two H1+ atoms. There is one shorter (1.59 Å) and one longer (1.60 Å) B–N bond length. Both B–H bond lengths are 1.21 Å. There are two inequivalent N2- sites. In the first N2- site, N2- is bonded to one B3- and three H1+ atoms to form corner-sharing NBH3 tetrahedra. All N–H bond lengths are 1.03 Å. In the second N2- site, N2- is bonded to one B3- and three H1+ atoms to form corner-sharing NBH3 tetrahedra. All N–H bond lengths are 1.03 Å. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one B3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one B3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N2- atom. In each B3H8 cluster, there are three inequivalent B3- sites. In the first B3- site, B3- is bonded in a distorted trigonal non-coplanar geometry to three H1+ atoms. There are a spread of B–H bond distances ranging from 1.21–1.27 Å. In the second B3- site, B3- is bonded in a 4-coordinate geometry to four H1+ atoms. There are a spread of B–H bond distances ranging from 1.21–1.48 Å. In the third B3- site, B3- is bonded in a distorted trigonal non-coplanar geometry to three H1+ atoms. There is two shorter (1.22 Å) and one longer (1.26 Å) B–H bond length. There are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in an L-shaped geometry to two B3- atoms. In the second H1+ site, H1+ is bonded in an L-shaped geometry to two B3- atoms. In the third H1+ site, H1+ is bonded in a single-bond geometry to one B3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one B3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one B3- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one B3- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Performance of Windows in Walls With Continuous Insulation

Window openings in walls are a significant contributor to poor thermal performance because of thermal bridging through the framing members (e.g., studs, joists, plates, bracing) and because windows lack the thermal properties of insulation. Window installation guidance for walls with continuous insulation (CI) is critical for continued market growth of this energy efficiency technology. This research project offers window manufacturers a starting point and a potential path toward developing installation instructions for windows over CI. The objectives of the research include evaluating the common method for installing windows in walls with CI, as well as establishing acceptance criteria for evaluating the performance of windows installed in walls with and without CI. The research measures: 1. The performance characteristics (e.g., water management, structural integrity) of windows in walls without CI. 2. The performance of different thicknesses and types of CI used in walls. 3. The performance of different types of window assemblies (e.g., double-hung windows, mulled double-hung windows, mulled casement windows, and slider windows) installed over CI. 4. The performance of window flange types (e.g., rigid mounting and less robust flanges) installed over CI. 5. Installing windows over CI using baseline installation instructions versus window manufacturer installation instructions. The project’s sequential testing protocol consists of the following: • A water penetration resistance testing adapted from two ASTM standards: E331 (uniform static air pressure in four steps) and E547 (cyclic static air pressure) • A temperature cycling adapted from ASTM E2264 Method B (convective hot air) • A service condition wind loading test adapted from ASTM E330 • A six-month vertical displacement observation phase prior to the structural performance testing • A final water penetration resistance test after vertical displacement observation • A structural performance test adapted from ASTM E330. Key research findings include: • The criterion for passing a water penetration resistance test is that there is no water overflowing at the interior face of the studs. If there is any bubbling or slight pooling of water at the sill, then it must recede after the pressure is removed. Excessive leakage and/or water leaking to the interior face of the framing around the window constitutes a failure. • All single double-hung windows installed directly to lumber or over oriented strand board passed all test protocols. • For most wall specimens, the test results showed that the use of foam sheathing did not affect the performance of the window for water leakage. • All wall specimens underwent temperature cycling. The results indicated that temperature cycling had little to no effect on windows installed over foam sheathing. • For wall specimens that underwent six-month vertical displacement monitoring, the results showed that windows installed over foam sheathing do not sag over time. • The single-hung and double-hung windows installed using window manufacturer installation instructions passed the structural performance test, compared to failures observed in windows that were installed using generic installation instructions. The generic and manufacturer installation methods differed on the following construction details: type of fasteners, fastening patterns on the flanges, and window shimming details. • Additional testing is required to determine methods to improve structural pressure performance of slider windows. Potential solutions that would require additional testing may include fastener spacing, different types of fasteners, masonry window clips, construction adhesive, foam sealant, stronger window flange material, and/or straps.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

SAF Combustion & Soot Processes [Slides]

The atomization, mixing, combustion and emissions characteristics of aviation fuels were measured using a novel approach based on a non-continuous injection scheme called the single-hole atomizer (SHA). High-speed microscopy revealed differences between fuels in terms of evaporation and mixing regimes over conditions relevant to modern and next generation aero-engine combustors. Measurements of liquid and vapor penetration, mixing fields, combustion and emissions metrics (ignition delay, lift-off length, PAH formation, soot mass) highlighted the effects of fuels and combustor conditions. The experimental results are being leveraged to adjust and validate chemical and CFD models. Detailed analysis of sampled soot showed subtle differences in soot morphology between fuels. The results revealed the presence of contaminants potentially affecting surface chemistry and the nucleation propensity of water droplets on particles. Chemical mechanisms for NJFCP A-2, C-1 and C-4 showed good performance over a large parameter space. Spray breakup at relight conditions is vastly different from the atomization observed at high pressure. CFD simulations of the SHA target conditions confirmed the good behavior of the C-1 kinetic mechanism. The simulations support the strong relationship between low and high temperature reactions. New altitude chamber facility to enable detailed characterization of the heterogeneous nucleation process of water on aerosol particles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Explanation and Application of the Evolving Contact Traction Fields in Shallow Foundation Systems

The present paper provides a qualitative discussion of the evolution of contact traction fields beneath rigid shallow foundations resting on granular materials. A phenomenological similarity is recognized in the measured contact traction fields of rigid footings and at the bases of sandpiles. This observation leads to the hypothesis that the stress distributions are brought about by the same physical phenomena, namely the development of arching effects through force chains and mobilized intergranular friction. A set of semi-empirical equations are suggested for the normal and tangential components of this contact traction based on past experimental measurements and phenomenological assumptions of frictional behaviors at the foundation system scale. These equations are then applied to the prescribed boundary conditions for the analysis of the settlement, resistance, and stress fields in supporting granular materials beneath the footing. A parametric sensitivity study is performed on the proposed modelling method, highlighting solutions to the boundary-value problems in an isotropic, homogeneous elastic half-space.

42 ENGINEERING↗
DOE OSTI2020

A Search for FeH in Hot-Jupiter Atmospheres with High-dispersion Spectroscopy

Most of the molecules detected thus far in exoplanet atmospheres, such as water and CO, are present for a large range of pressures and temperatures. In contrast, metal hydrides exist in much more specific regimes of parameter space, and so can be used as probes of atmospheric conditions. Iron hydride (FeH) is a dominant source of opacity in low-mass stars and brown dwarfs, and evidence for its existence in exoplanets has recently been observed at low resolution. We performed a systematic search of archival CARMENES near-infrared data for signatures of FeH during transits of 12 exoplanets. These planets span a large range of equilibrium temperatures (600 ≲ T eq ≲ 4000 K) and surface gravities (2.5 ≲ logg ≲ 3.5). We did not find a statistically significant FeH signal in any of the atmospheres, but obtained potential low-confidence signals (signal-to-noise ratio ~ 3) in two planets, WASP-33b and MASCARA-2b. Previous modeling of exoplanet atmospheres indicate that the highest volume mixing ratios (VMRs) of 10 -7 to 10 -9 are expected for temperatures between 1800 and 3000 K and log g≳3. The two planets for which we find low-confidence signals are in the regime where strong FeH absorption is expected. We performed injection and recovery tests for each planet and determined that FeH would be detected in every planet for VMRs ≫10 -6 , and could be detected in some planets for VMRs as low as 10 -9.5 . Additional observations are necessary to conclusively detect FeH and assess its role in the temperature structures of hot-Jupiter atmospheres.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Calculation of Hydraulic Conductivity for a Porous Medium with Staggered Array of Solid Grains - 20087

For a porous medium with periodic array of solid grains. the flow of an incompressible viscous fluid in the pore space is considered with an aim of calculating the permeability of the medium. The solid grains are of ellipsoidal shape. For this purpose, a unit-cell boundary-value problem (Stokes problem) is solved numerically. With the assumption of periodicity of the medium structure and the fluid properties (in fact constant), the flow field and pressure distributions are determined numerically with inertial effects ignored. By applying the theory of homogenization to the viscous flow through pore space, a microscale boundary-value problem is defined. After solving the problem, the permeability is determined by taking the micro-cell average of the velocity components, Various porous structures are chosen to allow a wide range of porosity values. The permeability increases mildly for porosity values in the lower range. But it increases sharply for porosity values in the upper range of the porosity. The permeability of the present study agrees with the Kozeny-Carman relation excellently for smaller porosity. Certain discrepancy between the calculated permeability in this study and the Kozeny-Carman relation appears and increases with porosity for larger porosity. It is believed that the discrepancy is due to the replacement of the pores by a bundle of capillaries, which is unrealistic, in the Kozeny-Carman relation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗