Results 261 to 270 of about 125,223 (284)
Some of the next articles are maybe not open access.
Effective Diffusion Coefficient in Porous Media
Journal of Applied Physics, 1963Recent calculations by Prager of upper bounds for the effective diffusion coefficient (or conductivity) in porous media, in terms of certain statistical parameters of the random geometry, are reformulated so as to apply specifically to a bed of spherical particles.
openaire +1 more source
Effective Diffusion Coefficient: From Homogenization to Experiment
Transport in Porous Media, 1997In this paper, an example of the application of the homogenization approach (asymptotic expansion technique) to predict the effective diffusion coefficient for an equivalent continuum, together with the experimental verification of the theoretical results is presented.
JEAN-LOUIS AURIAULT, JOLANTA LEWANDOWSKA
openaire +1 more source
Effective binary diffusion coefficients in mixed solvents
AIChE Journal, 1965AbstractThe diffusion of carbon dioxide through ethanol‐water, benzene toluene, and carbon tetrachloride benzene was studied over the entire range of compositions for the solvent pairs. The results were interpreted in terms of an effective binary diffusion coefficient.
Y. P. Tang, D. M. Himmelblau
openaire +1 more source
Effective diffusion coefficient for steady two-dimensional convective flow
Physical Review A, 1988We use the homogenization method to obtain an expression for the effective diffusion coefficient ${D}^{\mathrm{*}}$ for convective flows. We evaluate this expression numerically by a finite-mode truncation for two-dimensional laminar flows with arbitrary P\'eclet numbers. Our results allow us to establish the range of validity of the small- and large-P\
, McCarty, , Horsthemke
openaire +2 more sources
Evaluation of Ligand-Selector Interaction from Effective Diffusion Coefficient
Analytical Chemistry, 2010We present an analytical technique for determination of ligand-selector equilibrium binding constants. The method is based on the measurements of effective molecular diffusion coefficient of the ligand during Poiseuille flow through a long (approximately 25 m), thin (0.254 mm +/- 0.05 mm ID) capillary with and without the selector.
Anna, Bielejewska +4 more
openaire +2 more sources
Effective Diffusion Coefficients in Calcium Alginate Gel
Biotechnology Progress, 1987AbstractThe effective diffusion coefficient of glucose, De in calcium alginate gel determined at 35°C by two different methods gave values which, on average, were at least 24% less than in water. Assessment of the effect of glucose concentration on De seems to indicate that De increased with decreasing glucose concentration at very low concentrations ...
openaire +1 more source
Spin waves and spin diffusion in Fermi liquids: Bounds on effective diffusion coefficients
Physical Review B, 1986We investigate the accuracy of the usual relaxation-time approximations, involving the spin-diffusion lifetime tau/sub D/, which are generally made in analyses of spin waves and the Leggett-Rice effect in Fermi liquids. By employing the variational methods of Ah-Sam, Hojgaard-Jensen, and Smith and of Egilsson and Pethick, we are able to determine upper
, Bedell, , Meltzer
openaire +2 more sources
Consistent measurement of diffusion coefficients for effectiveness factors
Chemical Engineering Science, 1980Abstract An examination has been made of how structural factors influence the measured values of effective diffusivity using the steady(Wicke-Kallenbach) and unsteady (chromatographic) state methods. For a solid with a typical bidisperse pore size distribution it is shown that the steady state method tends to give longer values.
C. McGreavy, M.A. Siddiqui
openaire +1 more source
Effective Diffusion Coefficients for Low Density Cylindrical Channels
Nuclear Science and Engineering, 1980Diffusion theory overestimates neutron transport in voided or low-density regions of a reactor when the diffusion coefficient is defined as 1/3..sigma../SUB tr/. Alternative definitions of the diffusion coefficient for such regions have been proposed. The present paper summarizes some definitions of axial diffusion coefficient for cylindrical channels ...
J. L. Rowlands, C. R. Eaton
openaire +1 more source
?Uphill? hydrogen diffusion effects and hydrogen diffusion coefficients in palladium
International Journal of Hydrogen Energy, 1997Information concerning measurements of hydrogen diffusion coefficients over α- and β-phase ranges of hydrogen content in the palladium/hydrogen system is summarized. The utilization of palladium as a hydrogen purification membrane has constituted a background for observations of “uphill” hydrogen diffusion effects.
openaire +1 more source