scholarly journals Prediction Of Particle Laden Flow In Gas Pipe

2021 ◽  
Author(s):  
Mohsen. Hedayati-dezfooli
Keyword(s):  
Gas Phase ◽  
Numerical Approach ◽  
Continuous Phase ◽  
Core Region ◽  
High Mass ◽  
Dispersed Phase ◽  
Flow Profile ◽  
Particle Sizes ◽  
The Core ◽  
Turbulence Effect

In the present study, the behavior of various sizes of black powder particulates, carried by a turbulent flow of natural gas, is numerically predicated in a horizontal pipeline. The particles are magnetite and are considered as discrete or a dispersed phase; however, the gas phase is considered as a continuous phase. The numerical approach taken to simulate the dispersed phase is a Lagrangian approach, which is essentially computation of particles trajectories. The turbulence effect on the dispersion of the particles, due to turbulent eddies in the gas phase, is predicted using a stochastic discrete-particle approach. Several case studies have been examined and they include: instantaneous injection of diverse particle sizes, continuous injection of five different particle sizes and multiple injection. For the case with instantaneous injection, it has been found that sudden injection of relatively high mass loading of particles would alter the flow profile in the core region and subsequently increases the turbulent intensity. For all cases it has been found that most particles in the core region of the flow move faster than the gas. Also, for all studied cases, the velocity profiles of gas and particles, at different pipeline stations, have been presented and analyzed.

scholarly journals Prediction Of Particle Laden Flow In Gas Pipe

2021 ◽  
Author(s):  
Mohsen. Hedayati-dezfooli
Keyword(s):  
Gas Phase ◽  
Numerical Approach ◽  
Continuous Phase ◽  
Core Region ◽  
High Mass ◽  
Dispersed Phase ◽  
Flow Profile ◽  
Particle Sizes ◽  
The Core ◽  
Turbulence Effect

In the present study, the behavior of various sizes of black powder particulates, carried by a turbulent flow of natural gas, is numerically predicated in a horizontal pipeline. The particles are magnetite and are considered as discrete or a dispersed phase; however, the gas phase is considered as a continuous phase. The numerical approach taken to simulate the dispersed phase is a Lagrangian approach, which is essentially computation of particles trajectories. The turbulence effect on the dispersion of the particles, due to turbulent eddies in the gas phase, is predicted using a stochastic discrete-particle approach. Several case studies have been examined and they include: instantaneous injection of diverse particle sizes, continuous injection of five different particle sizes and multiple injection. For the case with instantaneous injection, it has been found that sudden injection of relatively high mass loading of particles would alter the flow profile in the core region and subsequently increases the turbulent intensity. For all cases it has been found that most particles in the core region of the flow move faster than the gas. Also, for all studied cases, the velocity profiles of gas and particles, at different pipeline stations, have been presented and analyzed.

Axial Dispersion in a Three-Phase Gas-Agitated Spray Extraction Column

1998 ◽  
Vol 63 (2) ◽  
pp. 283-292 ◽  
Author(s):  
Milan Sovilj
Keyword(s):  
Gas Phase ◽  
Dispersion Coefficient ◽  
Continuous Phase ◽  
Axial Dispersion ◽  
Superficial Velocity ◽  
Extraction Column ◽  
Dispersed Phase ◽  
Dispersion Coefficients ◽  
Axial Dispersion Coefficient ◽  
Three Phase

The continuous-phase axial dispersion coefficients of the three-phase gas-liquid-liquid system in a gas-agitated spray extraction column 10 cm i.d. at 20 °C were examined. The system used was water as continuous phase, toluene as dispersed phase, and air as gaseous phase. The rise in the gas phase superficial velocity increased the continuous-phase axial dispersion coefficient. A non-linear dependence between the continuous-phase axial dispersion coefficient and the continuous phase superficial velocity was observed. No correlation was found between the continuous-phase axial dispersion coefficient and dispersed phase superficial velocity. The increase in the gas phase hold-up corresponded to a slight increase in the continuous-phase axial dispersion coefficient. The increase in the dispersed phase hold-up generated a growth of the continuous-phase axial dispersion coefficient. A comparison was made of the continuous-phase axial dispersion coefficients of the three-phase (air-water-toluene) and two-phase (water-toluene) systems.

Intramitochondrial Viruses of Reptilian Cell Origin

1972 ◽  
Vol 30 ◽  
pp. 318-319
Author(s):  
Philip D. Lunger ◽  
H. Fred Clark
Keyword(s):  
Particle Production ◽  
Outer Zone ◽  
Density Variation ◽  
Core Region ◽  
Mitochondrial Membranes ◽  
Virus Particles ◽  
The Core ◽  
Vipera Russelli ◽  
Maturation Stages ◽  
Type Particle

In the course of fine structure studies of spontaneous “C-type” particle production in a viper (Vipera russelli) spleen cell line, designated VSW, virus particles were frequently observed within mitochondria. The latter were usually enlarged or swollen, compared to virus-free mitochondria, and displayed a considerable degree of cristae disorganization.Intramitochondrial viruses measure 90 to 100 mμ in diameter, and consist of a nucleoid or core region of varying density and measuring approximately 45 mμ in diameter. Nucleoid density variation is presumed to reflect varying degrees of condensation, and hence maturation stages. The core region is surrounded by a less-dense outer zone presumably representing viral capsid.Particles are usually situated in peripheral regions of the mitochondrion. In most instances they appear to be lodged between loosely apposed inner and outer mitochondrial membranes.

Phase Inversion in Two-Phase Liquid Systems

1992 ◽  
Vol 57 (7) ◽  
pp. 1419-1423
Author(s):  
Jindřich Weiss
Keyword(s):  
Interfacial Tension ◽  
Phase Inversion ◽  
Continuous Phase ◽  
Considerable Effect ◽  
Weak Dependence ◽  
Dispersed Phase ◽  
Two Phase ◽  
Liquid Systems ◽  
Phase Liquid

New data on critical holdups of dispersed phase were measured at which the phase inversion took place. The systems studied differed in the ratio of phase viscosities and interfacial tension. A weak dependence was found of critical holdups on the impeller revolutions and on the material contactor; on the contrary, a considerable effect of viscosity was found out as far as the viscosity of continuous phase exceeded that of dispersed phase.

Capillary pressure, osmotic pressure and bubble contact areas in foams

Soft Matter ◽  
2021 ◽  
Author(s):  
Reinhard Höhler ◽  
Jordan Seknagi ◽  
Andrew Kraynik
Keyword(s):  
Osmotic Pressure ◽  
Capillary Pressure ◽  
Continuous Phase ◽  
Dispersed Phase ◽  
Average Pressure ◽  
Contact Areas ◽  
The Difference

The capillary pressure of foams and emulsions is the difference between the average pressure in the dispersed phase and the pressure in the continuous phase.

scholarly journals Hunting for intermediate-mass black holes in globular clusters: an astrometric study of NGC 6441

2021 ◽  
Vol 503 (1) ◽  
pp. 1490-1506
Author(s):  
Maximilian Häberle ◽  
Mattia Libralato ◽  
Andrea Bellini ◽  
Laura L Watkins ◽  
Jörg-Uwe Pott ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Velocity Dispersion ◽  
Angular Resolution ◽  
Hubble Space Telescope ◽  
High Mass ◽  
High Angular Resolution ◽  
Stellar Kinematics ◽  
Intermediate Mass ◽  
The Core ◽  
Large Telescopes

ABSTRACT We present an astrometric study of the proper motions (PMs) in the core of the globular cluster NGC 6441. The core of this cluster has a high density and observations with current instrumentation are very challenging. We combine ground-based, high-angular-resolution NACO@VLT images with Hubble Space Telescope ACS/HRC data and measure PMs with a temporal baseline of 15 yr for about 1400 stars in the centremost 15 arcsec of the cluster. We reach a PM precision of ∼30 µas yr−1 for bright, well-measured stars. Our results for the velocity dispersion are in good agreement with other studies and extend already existing analyses of the stellar kinematics of NGC 6441 to its centremost region never probed before. In the innermost arcsecond of the cluster, we measure a velocity dispersion of (19.1 ± 2.0) km s−1 for evolved stars. Because of its high mass, NGC 6441 is a promising candidate for harbouring an intermediate-mass black hole (IMBH). We combine our measurements with additional data from the literature and compute dynamical models of the cluster. We find an upper limit of $M_{\rm IMBH} \lt 1.32 \times 10^4\, \textrm{M}_\odot$ but we can neither confirm nor rule out its presence. We also refine the dynamical distance of the cluster to $12.74^{+0.16}_{-0.15}$ kpc. Although the hunt for an IMBH in NGC 6441 is not yet concluded, our results show how future observations with extremely large telescopes will benefit from the long temporal baseline offered by existing high-angular-resolution data.

scholarly journals On the Nature of R 136, the Central Object of 30 Dor. A Comparison by the Galactic Cluster NGC 3603

1984 ◽  
Vol 108 ◽  
pp. 257-258
Author(s):  
Michael Rosa ◽  
Jorge Melnick ◽  
Preben Grosbol
Keyword(s):  
Core Region ◽  
H Ii Regions ◽  
Central Object ◽  
The Core ◽  
Dominant Component ◽  
Galactic Cluster ◽  
H Ii Region

The massive H II region NGC 3603 is the closest galactic counterpart to the giant LMC nebula 30 Dor. Walborn (1973) first compared the ionizing OB/WR clusters of the two H II regions and suggested that R 136, the unresolved luminous WR + 0 type central object of 30 Dor, might be a multiple system like the core region of NGC 3603. Suggestions that the dominant component of R 136, i.e. R 136A, might be either a single or a very few supermassive and superluminous stars (Schmidt-Kaler and Feitzinger 1982, Savage et al. 1983) have recently been disputed by Moffat and Seggewiss (1983) and Melnick (1983), who have presented spectroscopic and photometric evidence to support the hypothesis of an unresolved cluster of stars. We have extended Walborn's original comparison of the apparent morphology of the two clusters by digital treatment of the images to simulate how the galactic cluster would look like if it were located in the LMC

Effect of Geometry on Droplet Generation in a Microfluidic T-Junction

2013 ◽  
Author(s):  
Katerina Loizou ◽  
Wim Thielemans ◽  
Buddhika N. Hewakandamby
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Droplet Formation ◽  
Continuous Phase ◽  
Main Channel ◽  
Superficial Velocity ◽  
Droplet Generation ◽  
Dispersed Phase ◽  
Aspect Ratios ◽  
The Cross

The main aim of this study is to examine how the droplet formation in microfluidic T-junctions is influenced by the cross-section and aspect ratio of the microchannels. Several studies focusing on droplet formation in microfluidic devices have investigated the effect of geometry on droplet generation in terms of the ratio between the width of the main channel and the width of the side arm of the T-junction. However, the contribution of the aspect ratio and thus that of the cross-section on the mechanism of break up has not been examined thoroughly with most of the existing work performed in the squeezing regime. Two different microchannel geometries of varying aspect ratios are employed in an attempt to quantify the effect of the ratio between the width of the main channel and the height of the channel on droplet formation. As both height and width of microchannels affect the area on which shear stress acts deforming the dispersed phase fluid thread up to the limit of detaching a droplet, it is postulated that geometry and specifically cross-section of the main channel contribute on the droplet break-up mechanisms and should not be neglected. The above hypothesis is examined in detail, comparing the volume of generated microdroplets at constant flowrate ratios and superficial velocities of continuous phase in two microchannel systems of two different aspect ratios operating at dripping regime. High-speed imaging has been utilised to visualise and measure droplets formed at different flowrates corresponding to constant superficial velocities. Comparing volumes of generated droplets in the two geometries of area ratio near 1.5, a significant increase in volume is reported for the larger aspect ratio utilised, at all superficial velocities tested. As both superficial velocity of continuous phase and flowrate ratio are fixed, superficial velocity of dispersed phase varies. However this variation is not considered to be large enough to justify the significant increase in the droplet volume. Therefore it can be concluded that droplet generation is influenced by the aspect ratio and thus the cross-section of the main channel and its effect should not be depreciated. The paper will present supporting evidence in detail and a comparison of the findings with the existing theories which are mainly focused on the squeezing regime.

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