scholarly journals Determination of Volume Fractions in a Two-Phase Flows From Sound Speed Measurement

2012 ◽  
Author(s):  
Anirban Chaudhuri ◽  
Curtis F. Osterhoudt ◽  
Dipen N. Sinha
Keyword(s):  
Sound Speed ◽  
Volume Fraction ◽  
Quadratic Equation ◽  
Immiscible Fluids ◽  
Two Phase ◽  
Mean Values ◽  
Volume Fractions ◽  
Non Invasive ◽  
Instantaneous Temperature ◽  
The Difference

Accurate measurement of the composition of oil-water emulsions within the process environment is a challenging problem in the oil industry. Ultrasonic techniques are promising because they are non-invasive and can penetrate optically opaque mixtures. This paper presents a method of determining the volume fractions of two immiscible fluids in a homogenized two-phase flow by measuring the speed of sound through the composite fluid along with the instantaneous temperature. A linear chirp signal is transmitted through the fluid and de-chirp method is applied to calculate the sound speed in the medium. Two separate algorithms are developed by representing the composite density as (i) a linear combination of the two densities, and (ii) a non-linear fractional formulation. Both methods lead to a quadratic equation with temperature dependent coefficients, the root of which yields the volume fraction. The densities and sound speeds are calibrated at various temperatures for each fluid component, and the fitted polynomial is used in the final algorithm. We present results when the new algorithm is applied to mixtures of crude oil and process water from two different oil fields, and a comparison of our results with a Coriolis meter; the difference between mean values is less than 1%.

An Algorithm for Determining Volume Fractions in Two-Phase Liquid Flows by Measuring Sound Speed

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Anirban Chaudhuri ◽  
Curtis F. Osterhoudt ◽  
Dipen N. Sinha
Keyword(s):  
Seismic Waves ◽  
Volume Fraction ◽  
Quadratic Equation ◽  
Two Phase ◽  
Volume Fractions ◽  
Linear Rule ◽  
Calculated Volume ◽  
Instantaneous Temperature ◽  
The Individual ◽  
Liquid Flows

This paper presents a method of determining the volume fractions of two liquid components in a two-phase flow by measuring the speed of sound through the composite fluid and the instantaneous temperature. Two separate algorithms are developed, based on earlier modeling work by Urick (Urick, 1947, “A Sound Velocity Method for Determining the Compressibility of Finely Divided Substances,” J. Appl. Phys., 18(11), pp. 983–987) and Kuster and Toksöz (Kuster and Toksöz, 1974, “Velocity and Attenuation of Seismic Waves in Two-Phase Media: Part 1. Theoretical Formulations,” Geophysics, 39(5), pp. 587–606). The main difference between these two models is the representation of the composite density as a function of the individual densities; the former uses a linear rule-of-mixtures approach, while the latter uses a nonlinear fractional formulation. Both approaches lead to a quadratic equation, the root of which yields the volume fraction (φ) of one component, subject to the condition 0≤φ≤1. We present results of a study with mixtures of crude oil and process water, and a comparison of our results with a Coriolis meter. The liquid densities and sound speeds are calibrated at various temperatures for each fluid component, and the coefficients are used in the final algorithm. Numerical studies of sensitivity of the calculated volume fraction to temperature changes are also presented.

scholarly journals Simulation of the Effect of Oil Volume Fractions in an Oil-Water Flows Along a Circular Pipe: A Finite Element Approach

2018 ◽  
Vol 10 (5) ◽  
pp. 19
Author(s):  
Ferdusee Akter ◽  
Md. Bhuyan ◽  
Ujjwal Deb
Keyword(s):  
Finite Element ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Galerkin Approximation ◽  
Computational Domain ◽  
Two Phase Flows ◽  
Two Phase ◽  
Volume Fractions ◽  
Oil In Water ◽  
Element Approach

Two phase flows in pipelines are very common in industries for the oil transportations. The aim of our work is to observe the effect of oil volume fraction in the oil in water two phase flows. The study has been accomplished using a computational model which is based on a Finite Element Method (FEM) named Galerkin approximation. The velocity profiles and volume fractions are performed by numerical simulations and we have considered the COMSOL Multiphysics Software version 4.2a for our simulation. The computational domain is 8m in length and 0.05m in radius. The results show that the velocity of the mixture decreases as the oil volume fraction increases. It should be noted that if we gradually increase the volume fractions of oil, the fluid velocity also changes and the saturated level of the volume fraction is 22.3%.

scholarly journals Modeling of Two-Phase Flow in Rough-Walled Fracture Using Level Set Method

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Yunfeng Dai ◽  
Zhifang Zhou ◽  
Jin Lin ◽  
Jiangbo Han
Keyword(s):  
Crude Oil ◽  
Level Set Method ◽  
Level Set ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Contact Angles ◽  
Immiscible Fluids ◽  
Water Volume ◽  
Phase Flow ◽  
Two Phase

To describe accurately the flow characteristic of fracture scale displacements of immiscible fluids, an incompressible two-phase (crude oil and water) flow model incorporating interfacial forces and nonzero contact angles is developed. The roughness of the two-dimensional synthetic rough-walled fractures is controlled with different fractal dimension parameters. Described by the Navier–Stokes equations, the moving interface between crude oil and water is tracked using level set method. The method accounts for differences in densities and viscosities of crude oil and water and includes the effect of interfacial force. The wettability of the rough fracture wall is taken into account by defining the contact angle and slip length. The curve of the invasion pressure-water volume fraction is generated by modeling two-phase flow during a sudden drainage. The volume fraction of water restricted in the rough-walled fracture is calculated by integrating the water volume and dividing by the total cavity volume of the fracture while the two-phase flow is quasistatic. The effect of invasion pressure of crude oil, roughness of fracture wall, and wettability of the wall on two-phase flow in rough-walled fracture is evaluated.

Transmission Electron Microscopy (TEM) Observations of Phase-Separations of Gamma-Prime Precipitates in Ni-Al-Fe and Ni-Si-Fe Ternary Alloys

2007 ◽  
Vol 26-28 ◽  
pp. 1311-1314 ◽  
Author(s):  
M. Senga ◽  
H. Kumagai ◽  
Tomokazu Moritani ◽  
Minoru Doi
Keyword(s):  
Phase Separation ◽  
Volume Fraction ◽  
Heating Temperature ◽  
Ternary Alloys ◽  
Phase System ◽  
Precipitate Phase ◽  
Two Phase ◽  
Gamma Prime ◽  
Transmission Electron ◽  
The Difference

In Ni-13.0at%Si-3.1at%Fe alloy, when γ/γ’ two-phase microstructure formed at 1123 K is isothermally heated at 923 K which is lower than the temperature where the initial γ/γ’ microstructure forms, the phase-separation of γ/γ’ precipitate phase occurs and γ particles newly appear in each cuboidal γ’ precipitate. While in Ni-10.2at%Al-10.8at%Fe alloy, when γ/γ’ two-phase microstructure formed at 1023 K is isothermally heated at 1123 K which is higher than the temperature where the initial γ/γ’ microstructure forms, the phase-separation of γ’ precipitate phase takes place and γ particles newly appear in each cuboidal γ’ precipitate. Such appearance of new γ particles in γ’ precipitates can be explained by the difference in the volume fraction of γ phase that should exist in the γ/γ’ two-phase system depending on the heating temperature.

Using sound speed to determine volume fractions in a two‐phase flow.

2011 ◽  
Vol 129 (4) ◽  
pp. 2613-2613
Author(s):  
Anirban Chaudhuri ◽  
Curtis F. Osterhoudt ◽  
Dipen N. Sinha
Keyword(s):  
Sound Speed ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Volume Fractions

Phase-Separation of B2 Precipitates in an Fe-Ni-Al Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 2274-2278 ◽  
Author(s):  
Yasuhiro Kuno ◽  
Yasuo Nakane ◽  
Takao Kozakai ◽  
Minoru Doi ◽  
Junji Yamanaka ◽  
...  
Keyword(s):  
Free Energy ◽  
Phase Separation ◽  
Volume Fraction ◽  
Heating Temperature ◽  
Phase System ◽  
Al Alloy ◽  
Two Phase ◽  
Chemical Free Energy ◽  
The Difference ◽  
The Individual

When Fe-10.3mol%Ni-14.3mol%Al alloy is heated at 1173 K for 8.64104 s, a number of B2 precipitates are dispersed in the A2 matrix. When the two-phase microstructure of A2+B2 is aged at 973 K, the phase-separation of B2 precipitate particles takes place to form a new A2 phase in each B2 particle. In the course of further ageing at 973 K, the new A2 phase grows but decreases in number, and finally only one A2 particle is left in the individual B2 particles. The appearance of new A2 phase in each B2 precipitate is due to the difference in the volume fraction of A2 phase that should exist in A2+B2 two-phase system depending on the heating temperature: i.e., the phase-separation of B2 precipitates starts with the aid of chemical free energy.

Averaged equations for inviscid disperse two-phase flow

1994 ◽  
Vol 267 ◽  
pp. 185-219 ◽  
Author(s):  
D. Z. Zhang ◽  
A. Prosperetti
Keyword(s):  
Ad Hoc ◽  
Volume Fraction ◽  
Detailed Comparison ◽  
Momentum Equation ◽  
Average Pressure ◽  
Rigid Spheres ◽  
Two Phase ◽  
Averaged Equations ◽  
Mass Coefficient ◽  
The Difference

Averaged equations governing the motion of equal rigid spheres suspended in a potential flow are derived from the equation for the probability distribution. A distinctive feature of this work is the derivation of the disperse-phase momentum equation by averaging the particle equation of motion directly, rather than the microscopic equation for the particle material. This approach is more flexible than the usual one and leads to a simpler and more fundamental description of the particle phase. The model is closed in a systematic way (i.e. with no ad hoc assumptions) in the dilute limit and in the linear limit. One of the closure quantities is related to the difference between the gradient of the average pressure and the average pressure gradient, a well-known problem in the widely used two-fluid engineering models. The present result for this quantity leads to the introduction of a modified added mass coefficient (related to Wallis's ‘exertia’) that remains very nearly constant with changes in the volume fraction and densities of the phases. Statistics of this coefficient are provided and exhibit a rather strong variability of up to 20% among different numerical simulations. A detailed comparison of the present results with those of other investigators is given in § 10.As a further illustration of the flexibility of the techniques developed in the paper, in Appendix C they are applied to the calculation of the so-called ‘particle stress’ tensor. This derivation is considerably simpler than others available in the literature.

scholarly journals Changes in Retinal Multilayer Thickness and Vascular Network of Patients With Alzheimer’s Disease

2021 ◽  
Author(s):  
Xi Mei ◽  
Chenjun Zou ◽  
Conglong Qiu ◽  
Zhongming Chen ◽  
Yang Chen
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Retinal Thickness ◽  
Vascular Density ◽  
Fiber Layer ◽  
Mean Values ◽  
Non Invasive ◽  
Registration Number ◽  
Temporal Quadrant ◽  
The Difference

Abstract Background: Retinal biomarkers of Alzheimer’s disease (AD) were largely investigated during last decades. Brain conditions could be reflected by retinal nervous and vascular parameters. It can be used to enhance the accuracy of early diagnosis of AD.Objective: Our study aimed to evaluate the difference of retinal neuro-layer thickness and vascular parameters between AD patients and health control (HC) subjects.Methods: Non-invasive technology of optical coherence tomography angiography (OCTA) were adopted to acquire the combination thickness of retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), as well as the full retinal thickness (FRT). Vascular branch (VB), vascular curvature (VC), and vascular density (VD) were also collected in AD and HC groups. Mini-mental state examination (MMSE) was adopted to evaluate the cognitive levels of all subjects. After obtaining all the parameters, we used Mann-Whitney U test to compare the mean values of all retinal regions parameters between ADs and HCs. Pearson's correlation was used to test the association between retinal parameters and MMSE score, and vascular parameters.Results: Compared with HCs, the RNFL+GCL thickness of inferior quadrant, FRT of inferior and temporal quadrant, and retinal VD of patients with AD were significantly reduced (p < 0.05). The retinal thickness had significant correlations with MMSE scores (p < 0.05). Meanwhile, the retinal VD was significantly correlated with the average RNFL+GCL thickness (p < 0.05, r = 0.5956).Conclusion: In conclusion, our study suggested that AD patients had significant reduced RNFL+GCL thickness and vascular density compared with the age-matched HCs. Meanwhile, these reductions correlated with the cognitive level of the subjects. Trial registration number: ChiCTR2000035243Date of registration: Aug., 5, 2020URL of trial registry record: http://www.chictr.org.cn/index.aspx

scholarly journals Effect of ocular demodicosis on the stability of the tear film and the tear break up time

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aleksandra Sędzikowska ◽  
Witold Tarkowski ◽  
Joanna Moneta-Wielgoś ◽  
Krzysztof Grzyliński ◽  
Grzegorz Tarkowski ◽  
...  
Keyword(s):  
Tear Film ◽  
Hair Follicles ◽  
Film Stability ◽  
Mean Values ◽  
Non Invasive ◽  
Tear Film Stability ◽  
Break Up ◽  
The Difference ◽  
The Stability ◽  
The Impact

AbstractThe aim of the study was to analyze the correlation between the presence of Demodex mites in the hair follicles of patients' eyelashes and the stability and break up time of the tear film assessed with the Non-Invasive Tear Break Up Times (NIBUT) method. 319 patients were included in the study (195 women, 124 men). The patients were divided into two groups: those with Demodex infestation and without visible symptoms of eyelid or eye surface diseases, and asymptomatic non-infested patients. The NIBUT analysis was performed with a 5 M keratograph (oculus). Non-invasive tests were performed to identify the first and mean values of the tear break up time. The first and mean tear break up time in the Demodex-infested group was lower than in the non-infested subjects. The difference was a highly statistically significant. There was a significant correlation with the age of the patients for the first break up time. The first break up time in both eyes decreased with the age of the Demodex-infested and non-infested patients. The NIBUT analyses indicate the impact of Demodex mites on the tear film stability. This may suggest possible association of demodicosis with dry eye syndrome.

Experimental Study of Two-Phase Air/Water Flow in a Centrifugal Pump Working With a Closed or a Semi-Open Impeller

2018 ◽  
Author(s):  
Michael Mansour ◽  
Bernd Wunderlich ◽  
Dominique Thévenin
Keyword(s):  
Centrifugal Pump ◽  
Volume Fraction ◽  
Operating Conditions ◽  
Superior Performance ◽  
Flow Conditions ◽  
Two Phase ◽  
Volume Fractions ◽  
Acrylic Glass ◽  
Gas Volume Fraction ◽  
Gas Volume

The characteristics of a transparent centrifugal pump of radial type were investigated for different conditions when conveying two-phase (air/water) flows. A closed impeller and a geometrically similar semi-open impeller, both made out of acrylic glass, were employed for comparison purposes when increasing air loading. The performance of the pump was measured for either a constant gas volume fraction or a constant air flow rate at the pump inlet. Hysteresis effects were studied by considering three different experimental approaches to reach the desired operating conditions. A constant rotational speed of 650 rpm was set for all experiments. The whole system was made of transparent acrylic glass to allow high-quality flow visualization. A systematic experimental database was produced based on shadowgraphy imaging, so that the resulting two-phase regimes could be properly identified. The results show that for gas volume fractions between 1 and 3%, the deterioration of pump performance parameters is much lower in the semi-open impeller compared to that of the closed impeller. Nevertheless, in the gas volume fraction range between 4 and 6%, the trend is reversed; the semi-open impeller performance is reduced compared to the closed impeller, particularly in overload conditions. At even higher gas loading, the semi-open impeller shows again superior performance. Flow instabilities and pump surging were much stronger in the closed impeller. The main reason for that was the occurrence of alternating gas pockets on the blades of the closed impeller. Additionally, pump surging was observed only in a very limited range of flow conditions in the semi-open impeller. Comparing the different experimental procedures to set the desired flow conditions, no significant hysteresis effects could be observed in the closed impeller. However, in the semi-open impeller obvious hysteresis in the performance could be seen for gas volume fractions between 4 and 6%. All the obtained experimental results will be useful to check and validate computational models used for CFD in a comparison study.

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