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Multiphase Mixtures (multiphase + mixture)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

A simple method for compressible multiphase mixtures and interfaces

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2003
Nikolai Andrianov
Abstract We develop a Godunov-type scheme for a non-conservative, unconditional hyperbolic multiphase model. It involves a set of seven partial differential equations and has the ability to solve interface problems between pure materials as well as compressible multiphase mixtures with two velocities and non-equilibrium thermodynamics (two pressures, two temperatures, two densities, etc.).Its numerical resolution poses several difficulties. The model possesses a large number of acoustic and convective waves (seven waves) and it is not easy to upwind all these waves accurately and simply. Also, the system is non-conservative, and the numerical approximations of the corresponding terms need to be provided. In this paper, we focus on a method, based on a characteristic decomposition which solves these problems in a simple way and with good accuracy. The robustness, accuracy and versatility of the method is clearly demonstrated on several test problems with exact solutions. Copyright © 2003 John Wiley & Sons, Ltd. [source]

A standardless X-ray diffraction method for the quantitative analysis of multiphase mixtures.

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2002

In 1987, Rius, Plana & Palanques [J. Appl. Cryst. (1987), 20, 457,460] devised an X-ray powder diffraction method based on the `least-squares' determination of calibration constants using only the diffracted intensities and the calculated absorption coefficients of the components. This method was developed for `infinitely thick' samples, a condition which is seldom met by airborne particulates because of the small amount of material normally available. Since the analysis of such samples may become one of the principal applications of the method, this condition represents a serious limitation. The simplest way to overcome this limitation is by correcting the measured intensities. This can be done either by direct measurement of the sample transmission, or alternatively, by using refined transmission values. In the latter case no experimental values are necessary. With the help of some test calculations, the viability of both possibilities has been explored. [source]

Bitumen effects on pipeline hydraulics during oil sand hydrotransport

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2000
R. Sean Sanders
Abstract Oil sand hydrotransport technology has become increasingly important to Syncrude Canada Ltd. and the oil sands industry. Oil sand slurries are complex, multiphase mixtures of bitumen, coarse solids, fine solids, water and air that can exhibit time-dependent behaviour, wherein pipeline friction losses increase drastically with time. Four separate experimental programs were conducted to study the effect of bitumen on pipeline hydraulics using 100 mm and 250 mm (I.D.) recirculating and once-through pipeline loops. The results show that pipeline friction losses increase as a bitumen coating forms on the pipe wall. The effect is more pronounced at 50°C, but also occurs at lower temperatures. La technologie de l'hydrotransport des sables pétro-lifères revêt une importance de plus en plus grande pour Syncrude Canada et l'industrie des sables pétro-lifères. Les boues des sables pétrolifères sont complexes; elles contiennent des mélanges de bitumes multi-phasiques, des solides grossiers, des solides fins, de l'eau et de l'air qui peuvent parfois montrer un comportement évolutif, en particulier les pertes par frottement dans les conduites qui augmentent considérablement avec le temps. Quatre programmes expérimentaux différents ont été menés pour étudier l'effet du bitume sur les conditions hydrauliques des conduites au moyen de boucles de conduites en recirculation et sans recyclage de 100 et 250 mm de diamètre intérieur. Les résultats montrent que les pertes par frottement dans les pipelines augmentent lorsqu'une couche de bitume se forme sur la paroi de la conduite. L'effet est plus prononcé à 50°C, mais survient également à des températures plus basses. [source]