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1.
A numerical scheme is developed in order to simulate fluid flow in three dimensional (3‐D) microstructures. The governing equations for steady incompressible flow are solved using the semi‐implicit method for pressure‐linked equations (SIMPLE) finite difference scheme within a non‐staggered grid system that represents the 3‐D microstructure. This system allows solving the governing equations using only one computational cell. The numerical scheme is verified through simulating fluid flow in idealized 3‐D microstructures with known closed form solutions for permeability. The numerical factors affecting the solution in terms of convergence and accuracy are also discussed. These factors include the resolution of the analysed microstructure and the truncation criterion. Fluid flow in 2‐D X‐ray computed tomography (CT) images of real porous media microstructure is also simulated using this numerical model. These real microstructures include field cores of asphalt mixes, laboratory linear kneading compactor (LKC) specimens, and laboratory Superpave gyratory compactor (SGC) specimens. The numerical results for the permeability of the real microstructures are compared with the results from closed form solutions. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
2.
3.
Al. A. Suchkov 《Astrophysics》1985,23(1):452-458
4.
Zoran Knežević 《Celestial Mechanics and Dynamical Astronomy》1993,55(4):387-404
Leverrier's development of the indirect part of the disturbing function has been extended to include terms up to degree 4 in eccentricity and inclination; the resulting series has been expressed with respect to a fixed plane, and in a computer readable form (a list of integers). Tests have been performed for the relative significance of the terms of degrees 2, 3 and 4, and estimates have been obtained for the accuracy of the short periodic perturbations of a minor planet, and of the corresponding mean orbital elements. It was found that: (i) even in extreme cases, the indirect part of the disturbing function gives rise to very small short periodic perturbations; (ii) bodies of very high eccentricity/inclination and those close to mean motion resonances are most significantly affected; (iii) indirect perturbations for minor planets can be computed up to the degree 2 terms only, without any significant loss of accuracy; and (iv) higher degree indirect perturbations appear to be important only for their contribution to the long periodic effects of higher order (with respect to the perturbing mass). 相似文献
5.
The behaviour of the flare in the period of enhancement and maximum of hard X-ray, microwave and decimetric type IV continuum is analysed. The elongation of the H ribbons and microwave source disclose that the energy release site was shifting through a system of loops with a velocity less than 200 km s-1, and that the energy was carried down the field lines with a velocity of about 1000 km s-1, implying the thermal conduction front mechanism of energy transport. Several processes of energy release are considered and it is concluded that an explanation in terms of succeeding interactions of neighbouring loops, involving fast reconnection of their poloidal components is in best agreement with the observations.Proceedings of the Second CESRA Workshop on Particle Acceleration and Trapping in Solar Flares, held at Aubigny-sur-Nère (France), 23–26 June, 1986. 相似文献
6.
A. Čadež 《Astrophysics and Space Science》1985,109(2):399-402
We respond to comments made in a recent letter by Karimet al. (1984), and show that the examples of interstellar absorption at2800 Å that they have presented so far can all be attributed to overexposure of the IUE detectors. 相似文献
7.
The Ras Al-Subiyah area is considered one of the most promising areas in Kuwait for future development. This development will
include a new town called Subiyah and its associated infrastructure. This area is also being considered as the location for
connection between Boubyan Island, which is now undergoing major development and the Kuwait mainland. The present study investigates
the geomorphology of the Ras Al-Sabiyah area in the northern sector of Kuwait. The study area is generally flat, and it is
located west of the Jal Az-Zor escarpment. It is bordered on the east by the Khor Al-Sabiyah tidal channel and on the south
by Kuwait Bay. The area receives sediments from several sources; currently the most important are aeolian sediments and the
deposition of mud delivered through the Khor Al-Sabiyah from the Iraqi marshes. The study area has been subjected to severe
environmental changes due to the Gulf wars and the drainage of Iraqi marshes and the associated artificial changes in fluvial
system. Twenty-two surface sediments were collected from the Ras Al-Subiyah area. Samples were collected to include the main
geomorphologic characteristic features of the study area. Field observations and remote sensing images from 1990 and 2001
were used to produce an updated geomorphologic map for the Ras Al-Subiyah and a map showing geomorphic changes between 1990
and 2001. Grain size of the surface sediment ranges from gravel to medium sand. In general, grain size statistical analysis
indicates that most of the areas are composed of two or more classes of sands transported and deposited from different sources
including aeolian, sabkhas, river and the bays. The variability in the grain size statistical parameters may be attributed
to the complexity of surface morphology as well as the diversity in the type of depositional environment in the Ras Al-Subiyah
area. The total area subjected to change during the 12-year period (1990–2001) is about 32 km2 as calculated using GIS techniques. 相似文献
8.
M. Čadež 《Pure and Applied Geophysics》1960,47(1):172-182
Zusammenfassung Man beobachtet Antizyklonen, die als Folge einer Konzentration von Kaltluftmasssen auf ein kleineres Gebiet gedeutet werden können. Die Konzentration der Kaltluft ist durch die Umwandlung der kinetischen Energie der Kaltluft in potentielle Energie oder durch die Wärmezufuhr der kalten Luft bedingt. Solche Antizyklonen bilden sich oft in Berggebieten, da dort wegen der grossen äusseren Reibung die erwähnte Umwandlung der Energie beschleunigt wird. Wie gross solche antizyklogenetischen Effekte sein können, ist berechnet.
Summary The origin of some anticyclones can be explained as a consequence of the concentration of the cold air on a smaler area. The concentration of the cold air is caused by a transformation of the kinetic energy of the cold air into the potential energy or by the heating of the cold air. Such anticyclones often appear in mountain regions where the transformation of the mentioned energy is more intense. The intensity of such anticyclogenetical effects is evaluated.相似文献
9.
Antonín Papež 《Studia Geophysica et Geodaetica》1964,8(2):200-204
Резюме Дабление воздуха, переснитанное иа уровень моря по стандартной атмосфере в Q-коде обозчачается через QNH. Давление воздуха
пересчитанное на уровень моря по высотной барометрической формуле обознаеается через QFF. Для целей авиационной службы погоды
должны быть известны значения QNH, однако Зе барическое поле на синоптических картах выражается через QFF. С помощью рис.
1 для соответствующей температуры воздуха на станцин и ее высоты н. у. м. можно определить разность значений QFF—QNH при давленин
QFF=1000мб. Далее по табл. 2 можно определить поправку для каждого значения QFF отличного от значения QFF при ином давлении, чем 1000мб путем умножения табулированного значения ва разность QFF—1000мб и его алгебраического сложения со значением, полученным по рис. 1.
相似文献
10.
M. Čadež 《Pure and Applied Geophysics》1963,54(1):182-189
Résumé Dans cette étude l'explication de la formation des nuages Ac tra part de la supposition que l'air dans ce type de nuages est plus froid que l'air environnant, ce qui provoque certains courants convectifs dans la région du nuage. Ces courants ressemblent à ceux qui sont supposés par la théorie thermoconvective actuelle. D'après notre avis se trouvent des courants descendants audessous des petits nuages qui composent l'Ac tra, et les petits nuages qui forment l'Ac tra sont des corps séparés dont la température est moindre que la température de l'air environnant: c'est pour cela qu'ils tombent. Au contraire, d'après la théorie thermoconvective actuelle, l'air audessous de petits nuages monte et dans la distribution de la température des discontinuités n'existent pas.
Rapport présenté le 26 Avril 1962 à la Xème Assemblée Générale de laSocietà Italiana di Geofisica e Meteorologia (26–28 Avril 1962) 相似文献
Summary In this paper the explanation of the formation of clouds Ac tra is based on the assumption that the air in the cloud is colder than the surrounding air, causing convective currents in the region of the cloud. These currents are not unlike those assumed by the existing thermoconvective theory. According to the author's view there are descending currents under the cloudlets of which the Ac tra is made, and these cloudlets are separate bodies at a lower temperature than that of the surrounding air, so that the cloudlets fall. On the contrary, according to the existing thermoconvective theory, the air under the cloudlets rises and there are no discontinuities in the distribution of the temperature.
Rapport présenté le 26 Avril 1962 à la Xème Assemblée Générale de laSocietà Italiana di Geofisica e Meteorologia (26–28 Avril 1962) 相似文献