Four-phase Flow Research Articles

Numerical Analysis of Slag–Steel–Air Four-Phase Flow in Steel Continuous Casting Model Using CFD-DBM-VOF Model

Argon injection is usually applied in the continuous casting mold to prevent submerged entry nozzle (SEN) clogging. However, the stability of the slag–steel interface is affected by the injected gas, even leading to the formation of the slag eye. A computational fluid dynamics–discrete bubble model–volume of fluid (CFD-DBM-VOF) model is established to predict the argon–slag–steel–air four-phase flow in the continuous casting mold. The bubble behavior is treated with the Lagrangian approach considering bubble coalescence and breakup. The movement behavior of the slag–steel interface is analyzed with and without argon blowing, validated with the water model. The results show that the large bubble tends to float up into the slag–steel interface near the SEN with argon injection, resulting in fluctuations in the slag–steel interface near the SEN. The bubble distribution, flow field, fluctuation height of the slag–steel interface and configuration of the slag eye in the mold are analyzed. Furthermore, the effect on the casting speed, gas flow rate and thickness of the slag layer is obtained based on the result. The mathematical prediction results showcase a combination of well-established phenomena and newly generated predictions.

Multi-Scale Simulations of Bubble Transport in an Alkaline Water Electrolyzer

The existence of bubbles can lead to the loss of performance by decreasing the electrochemically active surface area and disrupting the transport of hydroxide ions. These effects caused by the bubbles have yet to be sufficiently clarified. A comprehensive understanding of the mechanisms of dynamics inside an electrolyzer from the molecular scale up to the whole electrolyzer scale is needed. Furthermore, establishing relations between these dynamics at a wide range of scales is important. In this study, numerical simulations of bubble transport coupling fluid dynamics, mass transport and electrochemical reactions were conducted on micro and macro scales, respectively. The micro scale bubble simulation (Fig. 1(a)) incorporates the concentration field of the chemical species into the numerical model and deals with how bubbles grow on and detach from an electrode. In this model, the chemical species generated by the electrochemical reactions dissolve into the liquid phase, and their transfer into the gas phase leads to bubble growth. Since the spatial size distribution of the bubbles can be one of the factors that affect electrolysis performance, in the macro scale bubble simulation (Fig. 1(b)), we study how different sizes of bubbles are transported and distributed inside the electrolyzer. To simulate this phenomenon, a four-phase flow analysis is performed in which small, medium, and large diameters are selected as representatives of bubble diameters, and each is treated as a different phase.[Acknowledgements]This study was based on results obtained from the Development of Fundamental Technology for Advancement of Water Electrolysis Hydrogen Production in Advancement of Hydrogen Technologies and Utilization Project (P14021) commissioned by the New Energy and Industrial Technology Development Organization (NEDO).Fig. 1 Simulation systems of bubble transport at (a) micro scale and (b) macro scale. Figure 1

Large Eddy Simulation on Four-Phase Flow and Slag Entrainment in the Slab Continuous Casting Mold

Large Eddy Simulation on Four-Phase Flow and Slag Entrainment in the Slab Continuous Casting Mold

Experimental investigation of different simulated formation water salinity in three-phase waxy crude oil-water-gas flow in horizontal pipes

Three-phase oil-water-gas flow experiments have been conducted in a horizontally configured rig made of carbon steel pipe with an ID of 0.041 m and a total length of 24.3 m. The test fluids were Malaysian waxy crude oil from Malay basin and three concentrations of simulated formation water salinity, namely 0 ppm, 15 000 ppm, and 30 000 ppm. The waxy crude oil and simulated formation water are varied at six different superficial liquid velocities ranging from 0.5 to 3.0 m/s while the gas phase is varied at 10 different superficial velocities ranging from 0.01 to 0.61 m/s. Eight flow patterns are observed using observational method; one of which is a newly discovered flow pattern identified as Slug with Oil Film-Oil Continuous (SLOF-OC). Salinity does not give significant effect on oil-gas interface but significantly affects the oil-water interface as lower formation water salinity is dispersed easily in crude oil compared to higher formation water salinity. The highest pressure gradient recorded was 2506.84 Pa/m at the highest superficial gas velocity while the lowest pressure gradient recorded was 89.53 Pa/m at the lowest superficial gas velocity. It is imperative to note that the experimental investigation of Malaysian waxy crude oil with different formation salinity in the three-phase flow study is in an unchartered area, therefore it provides a new platform for furthering more complex research works such as four-phase flow (gas, oil, water, and wax particles) below Wax-Appearing Temperature (WAT).

Diagnostic performance of serology against histologic assessment to diagnose Sjogren’s syndrome: a systematic review

The objective of this review was to assess and evaluate whether the published diagnostic accuracy studies provide evidence to sustain the current diagnostic guidelines put forth by ACR/EULAR used for patients with suspected Sjögren's syndrome (SS). Literature databases, including Medline, Embase, and EBM Reviews, were searched for relevant studies on the correlation between ACR/EULAR criteria, particularly those with a direct comparison between their accuracy in diagnosing Sjögren's syndrome. We followed Cochrane, QUADAS-2, and STARD guidelines and the four-phase flow diagram by the PRISMA Statement. Reports in several languages, but only human studies were considered. Three studies assessed the accuracy of the current diagnostic tests, and these did not present adequate designs that would allow a well-supported conclusion with a high level of certainty. Due to significant clinical and methodological heterogeneity, a meta-analysis was not performed. A qualitative review of the papers was undertaken. Neither the comparative nor the non-comparative study designs permit conclusive recommendations regarding an alternative diagnostic pathway for SS. Well-designed studies of the diagnostic accuracy of SS tests are needed to validate current guidelines or to suggest changes to the current guidelines.

Augmented reality technology as a tool to support chemistry learning: a scoping review

The purpose of this scoping review was to provide a comprehensive overview of relevant research regarding the use of Augmented Reality, the links to pedagogy and educational outcomes, specifically in the context of chemistry learning. The scoping review is underpinned by the five-stage Arksey and O’Malley framework. First, research questions are identified. Second, the last ten years studies are explored by using the key word ‘augmented reality + chemistry learning.’ Third, studies are investigated through inclusion and exclusion criteria, and PRISMA model is utilized for article selection. PRISMA model used in the form of four-phase flow diagram, including: identification, screening, eligibility, and included. Fourth, selected articles are charted with respect to numerous dimensions and summaries. Finally, findings are reported in the light of research questions. The findings of the scoping review illustrated a set of studies that provide evidence of improved conceptual understanding, increase in students’ interest, engagement, motivation, and satisfaction through the educational environments that are enriched with AR applications. The findings of the scoping review are discussed with respect to multiple dimensions that are explored under research questions.

Advance Machine Learning Methods for Dyslexia Biomarker Detection: A Review of Implementation Details and Challenges

Dyslexia is a neurological disorder that is characterized by imprecise comprehension of words and generally poor reading performance. It affects a significant population of school-age children, with more occurrences in males, thus, putting them at risk of poor academic performance and low self-esteem for a lifetime. The long-term hope is to have a dyslexia diagnostic method that is informed by neural-biomarkers. In this regard, large numbers of machine learning methods and, more recently, deep learning methods have been implemented across various types of dataset with the above-chance classification accuracy. However, attainment of clinical acceptability of these state-of-the-art methods is bedeviled by certain challenges including lack of biologically-interpretable biomarkers, privacy of dataset and classifiers, hyper-parameter selection/optimization, and overfitting problem among others. This review paper critically analyzes recent machine learning methods for detecting dyslexia and its biomarkers and discusses challenges that require proper attentions from the users of deep learning methods in order to enable them to attain clinically relevance and acceptable level. The review is conducted within the premise of implementation and experimental outcomes for each of the 22 selected articles using the Preferred Reporting Items for Systematic review and Meta-Analyses (PRISMA) protocol, with a view to outlining some critical challenges for achieving high accuracy and reliability of the state-of-the-art machine learning methods. As an evidence-based protocol for reporting in systematic reviews and meta-analyses, PRISMA helps to ensure clarity and transparency of this paper by showing a four-phase flow diagram of the selection process for articles used in this review. It is therefore, envisaged that higher classification performance of clinical relevance can be achieved using deep learning models for dyslexia and its biomarkers by addressing identified potential challenges.

Young GI angle: Why and how to write a good review article.

Young GI angle: Why and how to write a good review article.

Numerical investigation on the difference of dispersion behavior between cryogenic liquid hydrogen and methane

The potential hazard of cryogenic and combustible liquid propellants (hydrogen and methane) leakage caused by spontaneous damage of tanks or rupture of pipelines is still a problem for both applications and human beings. Numerical simulations have been performed to predict the fuels’ leakage and dispersion behavior differences. Based on liquid hydrogen release tests conducted by the Health & Safety Laboratory (HSL), a mixture four-phase flow model considering the liquid hydrogen and air phase transitions has been developed. The liquid phase movements in the near field, combustible clouds and cold effect clouds movement in the far field were investigated. With Froude number increases from 0.47 to 3.72, liquid hydrogen represents a downward trend while liquid methane shows a downwind trend. For combustible clouds, the movements of hydrogen are larger than that of methane in both downwind and vertical direction on a quasi-stable state. For cold effect clouds, the dispersion of methane is greater than that of hydrogen in Froude number of 0.47, 0.93, 1.86, but then smaller in larger Froude number of 3.72.

Effect of Flow Rate Difference of Flow Phases on Synthesis of Gold Nanoparticles using Four-phase Flow Microfluidic Device

Effect of Flow Rate Difference of Flow Phases on Synthesis of Gold Nanoparticles using Four-phase Flow Microfluidic Device

The Effect of War to the Nigerian Educational Activities: A Systematic Review

War is the leading cause of destruction to educational sector in Nigeria, in particular, the primary and secondary school education system. The focused of this review is to examine how the war affects the entire educational system of Nigeria by leading to the prevalence of numerous problems that hinder the successful achievement for “Educational for All” and the new Millennium Development Goal. The exploration activities of related references on the effect of war were systematically guided by PRISMA Statement which consists of a 27-item checklist and a four-phase flow diagram. The Prisma Diagram Generator was also utilized to generate the process of scrutinizing the articles. The end results render Nigeria as backward and the poverty-stricken nation that made it very difficult to support and sustain its educational sector according to global standard as enshrined by UNICEF.

Numerical Simulation of Slag Eye Formation and Slag Entrapment in a Bottom-Blown Argon-Stirred Ladle

A transient mathematical model is developed for simulating the bubble-steel-slag-top gas four-phase flow in a bottom-blown argon-stirred ladle with a 70-ton capacity. The Lagrangian discrete phase model (DPM) is used for describing the moving behavior of bubbles in the steel and slag. To observe the formation process of slag eye, the volume of fluid (VOF) model is used to track the interfaces between three incompressible phases: metal/slag, metal/gas, and slag/gas. The complex multiphase turbulent flow induced by bubble-liquid interactions is solved by a large eddy simulation (LES) model. Slag eye area and slag droplet dispersion are investigated under different gas flow rates. The results show that the movement of bubbles, formation and collapse of slag eye, volatility of steel/slag interface and behavior of slag entrapment can be properly predicted in the current model. When the gas flow rate is 300 L/min, the circulation driven by the bubble plume will stir the entire ladle adequately and form a slag eye of the right size. At the same time, it will not cause strong erosion to the ladle wall, and the fluctuation of the interface is of adequate intensity, which will be helpful for improving the desulfurization efficiency; the slag entrapment behavior can also be decreased. Interestingly, with the motion of liquid steel circulation, the collision and coalescence of dispersed slag droplets occur during the floating process in the vicinity of the wall.

285 Non-pharmacological interventions for people with fibromyalgia: a systematic review

Background: Fibromyalgia (FM) affects approximately 2% of the population and characterised by chronic widespread pain, fatigue, sleep and cognitive problems. The revised European League Against Rheumatism (EULAR) recommendations for the management of FM advise that initial management should focus on patient education and non-pharmacological interventions. This systematic review aimed to evaluate the evidence-base for non-pharmacological interventions to improve the health related quality of life of people with FM. Methods: Database search included Medline (OVID), Allied and Complementary Medicine Database (AMED), CINAHL, Health Management Information Consortium (HMIC) and PsychINFO up to July 2017. The 27-item PRISMA statement checklist and a four-phase flow diagram were used to guide the review process. Randomised controlled trials (RCT) were assessed for methodological quality using the 11-item Critical Appraisal Skills Programme (CASP) checklist for RCTs by two researchers. Results: Fourteen studies published between 2003 and 2017 were included in the full review following the systematic elimination process. Interventional approaches included multi-disciplinary (MDT) rehabilitation, patient education, cognitive behavioural therapy (CBT), aquatic or aerobic-based exercise, an internet based pain course, mindfulness meditation, movement therapy and acceptance & commitment therapy (ACT). Most common outcome measure used was Fibromyalgia Impact Questionnaire (FIQ) (11 out of 14 studies) which has three domains to measure function, overall impact and symptoms of FM. Evidence to support non-pharmacological interventions for management of FM ranged from low to moderate quality rated by CASP. Majority of studies (n = 13) reported statistically significant changes in participant’s psychological status, pain, anxiety and depression, functional capacity, motivation and sleep scores post-intervention. The evidence to support the positive impact of patient education and combined exercise on quality of life of people with FM was consistent across the studies. However, there was no evidence to support the effectiveness of mindfulness meditation and Qigong movement therapy over and above patient education. MDT rehabilitation improved functional status and physical activity level, as well as significant changes in health outcomes up to 15 months post-intervention. In terms of ACT, less pain and better overall functionality was reported nine months post-intervention, when compared to control. CBT resulted in some improvements in FM symptoms, but only in the short-term. Limitations included small sample sizes, high attrition rates, short follow-ups and lack of patient partner involvement in design and development of studies. Although statistically significant findings were reported, clinical importance of these scores was only touched upon by nine studies. Also, mixed-methods trial design was only adopted by one study. Conclusion: The RCT evidence to support non-pharmacological interventions for FM range from low to moderate quality and main recommendations encompasses patient education and combined exercise therapy. There is a need for large-scale, mixed-methods, longer term RCTs designed with patient research partner involvement to investigate wide range of treatment modalities.

State-of-the-art adaptive mesh generator implementation for dynamic asphaltene deposition in four-phase flow simulator in near well-bore region

Asphaltene deposition leads to rigorous problems in petroleum industry such as relative permeability reduction, wettability alterations, and blockage of the flow with additional pressure drop in wellbore tubing, etc. Many attempts have been undertaken to develop reliable and accurate models to predict phase behavior of asphaltene. However, previously published models cannot couple static and dynamic behaviors of reservoir and its fluids. In this communication, a novel four-phase flow simulator has been developed considering asphaltene deposition as one of the phases, using finite volume formulation. A novel adaptive unstructured mesh generator technique has been introduced in which dynamic properties of reservoir are combined with static field parameters. The results of this study illustrated that the proposed methodology can accurately predict the oil sample properties, and the amount of asphaltene precipitation. Moreover, it was found that the proposed approach is faster and computationally less expensive compared to fine structured model. The proposed strategy can be applied in any reservoir simulator and provides asphaltene phase behavior and reservoir properties with high degree of accuracy.

Large Eddy Simulation of Bubbly Flow and Slag Layer Behavior in Ladle with Discrete Phase Model (DPM)–Volume of Fluid (VOF) Coupled Model

In the ladle metallurgy process, the bubble movement and slag layer behavior is very important to the refining process and steel quality. For the bubble–liquid flow, bubble movement plays a significant role in the phase structure and causes the unsteady complex turbulent flow pattern. This is one of the most crucial shortcomings of the current two-fluid models. In the current work, a one-third scale water model is established to investigate the bubble movement and the slag open-eye formation. A new mathematical model using the large eddy simulation (LES) is developed for the bubble–liquid-slag-air four-phase flow in the ladle. The Eulerian volume of fluid (VOF) model is used for tracking the liquid-slag-air free surfaces and the Lagrangian discrete phase model (DPM) is used for describing the bubble movement. The turbulent liquid flow is induced by bubble–liquid interactions and is solved by LES. The procedure of bubble coming out of the liquid and getting into the air is modeled using a user-defined function. The results show that the present LES–DPM–VOF coupled model is good at predicting the unsteady bubble movement, slag eye formation, interface fluctuation, and slag entrainment.

Development of a hybrid black-oil/surfactant enhanced oil recovery reservoir simulator

Abstract The need for improved models to simulate chemical enhanced oil recovery (CEOR) methods involving either free gas or solution gas has increased in recent years as it has become more common to inject surfactants to recover live oils using surfactant-polymer or alkaline-surfactant-polymer flooding, or to inject gas with the surfactant solution (low-tension gas flooding or foam). A four-phase flow and transport formulation is needed to accurately model these EOR methods. New experimental data are now available to help in the development and validation of such models. In particular, the effect of pressure and solution gas on microemulsion phase behavior is now much better understood because of new and much more systematic experimental data. New low-tension gas or alkali surfactant foam experiments have also recently been published. In this paper, we present a four-phase flow formulation implemented in the numerical reservoir simulator UTCHEM, a compositional model developed specifically to simulate both lab-scale and field-scale chemical EOR. UTCHEM includes a third-order TVD finite-difference method to improve numerical accuracy of the extremely non-linear chemical processes. A black-oil model for water/oil/gas is coupled with the surfactant/oil/water (microemulsion) phase behavior model through a new formulation. The new formulation includes water, oil, gas, surfactant, polymer and electrolyte components in the aqueous, oleic, microemulsion and gas phases. The PVT properties are calculated for each phase using this model. The impact of pressure and solution gas on the optimum salinity and interfacial tension will be discussed. The four-phase flow simulator has been used to model low-tension gas flooding taking into account process mechanisms. The results aid in the understanding and interpretation of four-phase flow chemical EOR processes. The simulator can be used to evaluate chemical EOR methods involving solution gas and/or free gas, to scale up lab experiments to the field and to optimize chemical EOR process design for field tests among other applications. The need for a reliable mechanistic simulator has greatly increased due to more field applications of chemical EOR with gas and the expected further increase of this type of EOR.

CFD analysis of bubble column reactor under gas–oil–water–solid four-phase flows using Lagrangian algebraic slip mixture model

A Lagrangian algebraic slip mixture model (LASMM) has been developed to study gas–oil–water–solid four-phase flow. In this model the slip velocities between continuous and dispersed phases were derived from the Lagrangian movement equation. Therefore the slip velocities are able to consider the effects of various interfacial forces, such as buoyancy, drag, lift, virtual mass and turbulent dispersion. This model is easily coded through the user defined functions (UDFs) linking to the commercial or open source software. The validations were carried out through the comparisons of the numerical simulations to the experiments of gas–water–solid and gas–oil–water three-phase flows. For the validations of gas–water–solid three-phase flows, the simulation results compared to Michele and Hempel’s (2002) experiments on a cylindrical bubble column reactor. The comparisons were carried out by the quantitative comparisons on the axial water velocity under different inlet superficial gas velocities. For the validations of gas–oil–water three-phase flows, the simulation results compared to Descamps et al.’s (2007) experiments on a vertical pipe. The comparisons were performed by the quantitative comparisons of the gas volume fractions at different water cuts under different inlet flow conditions. After the validations, this model was used to study the gas–oil–water–solid four-phase flows in the bubble column reactor. The distributions of the solid phase and gas phase under different situations of oil-in-water and water-in-oil flows were studied. It was found that following the increase of the water cuts, in the oil-in-water flows, the solid particles were pushed away from the center of the column; however the solid particles were absorbed into the center of the column in the water-in-oil flows. The CFD work evaluates the aptness of the LASMM to predict the motion of a gas–oil–water–solid mixture to further the understanding of such complex reaction processes.

Microfluidic preparation and structure evolution of double emulsions with two-phase cores

In this work, we developed a simple capillary microfluidic device to prepare double emulsions with two-phase cores. We can control the structure and size of double emulsions by changing four-phase flow rates. Based on the formation of these four-phase double emulsions, we investigated the structure evolution of the double emulsions for different systems, and successfully obtained different multiple emulsions with four typical inner structures, as a separately engulfing structure, triple emulsion structure, Janus-engulfing structure, and inner-Janus structure. The equilibrium morphologies of the double emulsions could be estimated by using the relationship of interfacial tension between different phase fluids. Remarkably, the physics of evolution of double emulsions with two-phase cores in a microfluidic device allows the synthesis of microparticles with new morphologies and more applications in encapsulation of multiple active substances.

Research Paper Psychological treatments for eating disorders: What is the importance of the quality of the therapeutic alliance for outcomes?

BackgroundResearch data suggests that eating disorders symptomatology is determined by the individual’s unique combination of biological and psychological factors, in relation to their familial and social backgrounds (Brumberg, 2000). This means that different clients may benefit from different psychological interventions (Lock et al., 2010).PurposeThis systematic review investigates the significance of the quality of the therapeutic alliance for the effectiveness of psychological treatments with eating disorders.MethodA review of electronic databases was conducted against pre-determined exclusion and inclusion criteria, with applicable studies been abstracted using the PRISMA four-phase flow diagram (Moher et al., 2009). Nine quantitative and two qualitative studies which were published prior to June 2012 were included, and their data are critically considered and analysed.FindingsThe quality of the therapeutic alliance is significantly associated with the success of treatment outcome for anorexia nervosa, although its importance remains unclear for bulimic individuals.DiscussionPossible reasons behind the ambiguity of the results are discussed, and alternative contributors to successful treatment outcomes are incorporated.ConclusionNotwithstanding the fact that this systematic review encountered a number of limitations, the findings could inform practice as well as form the basis for additional research in the field of eating disorders.

Reduced-Emission Completions Improve Safety, Decrease Footprint

Green completions In its proposed New Source Performance Standards (NSPS) established in August 2011, the EPA estimated that, of the 25,000 new and modified fractured gas wells completed each year, approximately 3,000 to 4,000 currently employ reduced-emission completion (REC). Once finalized, the new rule will increase this number to more than 21,000 RECs annually as operators comply with the proposed NSPS. By 2015, every hydraulically fractured well will be required to use a green completion to capture and measure all oil and gas released during the flowback and drillout phases. Typically, the gas/liquid separator installed for normal well flow is not designed for the high-rate, four-phase (gas, hydrocarbon liquid, water, and sand) flow of a typical shale well. A common practice for the initial well completion has been to produce the well to a pit or tanks where water, hydrocarbon liquids, and sand are captured and slugs of gas vented to the atmosphere or flared. Completions can take anywhere from one day to several weeks, during which time a substantial amount of gas may be released to the atmosphere or flared. Green completion equipment is only necessary for the time it takes to complete the well. Operators typically transport this system from site to site to be used in a number of well completions, often on a truck-mounted skid. Don Atencio, manager at Fracmaster, said, “The setup for a green completion depends on the area and the type of well you are completing.” There is no set amount of equipment that is required. An REC can be performed with one self-contained unit, or it can be set up using individual components. Each job is based on need, the volume of gas and fluids being produced, and the size of the pad. For a multiwell pad, the equipment set up can be extensive. “Some of the work we are doing in New Mexico involves three major pieces of equipment that are too big to load onto one skid,” Atencio said.