bluuebunny/crossref_metadata_2025 huggingface dataset:
An exploration of pregnant teenagers' views of the future and their decisions to continue or terminate their pregnancy: implications for nursing care
Authors: Bell Emily R , Glover Lesley , Alexander Tim
Published: December 2013

Aims and objectives

To explore teenagers' views of the future in relation to their choices to continue or terminate pregnancy.

Background

Despite recent decreases in the numbers of teenage pregnancies, across the world, the teenage pregnancy rate remains high. Consideration of views of the future (future orientation) appears to play an important part in teenage girls' decisions to continue with pregnancy. To date, no study has explored this in teenage pregnant girls at the time they make their decision to continue with or terminate their pregnancy.

Design

Cross‐sectional mixed methods design.

Methods

Three groups were included: termination of pregnancy (n = 19), antenatal (n = 9) and never pregnant (n = 23). Participants were 13–18 years old. The termination of pregnancy and antenatal groups were interviewed, and the never pregnant group completed postal questionnaires.

Results

Groups differed in individual aspects of future orientation, that is, education, career and family, and reasons for pregnancy resolution choice. The termination group had more clearly developed and longer‐term plans for the future with a focus on career. The never pregnant group shared aspects of their future orientation with both the antenatal and termination of pregnancy groups. The impact of negative discourses about teenage pregnancy from others was identified as a significant issue.

Conclusions

How pregnant teenage girls view the future has a relationship with their decision to terminate or continue with their pregnancy.

Relevance to clinical practice

The findings suggest that working with teenage girls to clarify their views of the future may be useful both in preventing future unwanted pregnancy and in supporting teenagers in making pregnancy decisions. Supporting pregnant teenagers in distancing themselves from negative stereotypes of teenage mothers may also be beneficial.
Genetic factors may play a prominent role in the development of coronary heart disease dependent on important environmental factors
Authors: Song C. , Chang Z. , Magnusson P. K. E. , Ingelsson E. , Pedersen N. L.
Published: December 2013

Objective

The aim of the study was to examine whether various lifestyle factors modify genetic influences on coronary heart disease (CHD).

Design

The effect of lifestyle factors [including smoking, sedentary lifestyle, alcohol intake and body mass index (BMI)] on risk of CHD was evaluated via Cox regression models in a twin study of gene–environment interaction. Using structure equation modelling, we estimated genetic variance of CHD dependent on lifestyle factors.

Subjects

In total, 51 065 same‐sex twins from 25 715 twin pairs born before 1958 and registered in the Swedish Twin Registry were eligible for this study. During the 40‐year follow‐up, 7264 incident CHD events were recorded.

Results

Smoking, sedentary lifestyle and above average BMI were significantly associated with increased CHD incidence. The heritability of CHD decreased with increasing age, as well as with increasing levels of BMI, in both men and women.

Conclusions

The difference in the genetic component of CHD as a function of BMI suggests that genetic factors may play a more prominent role for disease development in the absence of important environmental factors. Increased knowledge of gene–environment interactions will be important for a full understanding of the aetiology of CHD.
The formulation, chemical and physical characterisation of clarithromycin-based macrolide solution pressurised metered dose inhaler
Authors: Saadat Alessandro , Zhu Bing , Haghi Mehra , King Gregory , Colombo Gaia , Young Paul M , Traini Daniela
Published: December 2013

Objectives

The formulation of a clarithromycin (CLA) pressurised metered dose inhalers (pMDIs) solution formulation opens up exciting therapeutic opportunities for the treatment of inflammation in chronic obstructive lung diseases. In this study, we have formulated and tested a low dose macrolide formulation of CLA for treatment of inflammation and studied its physicochemical and aerosol properties.

Methods

The system was characterised for in-vitro aerosol performance using an Andersen cascade impactor. Short-term chemical and physical stability was assessed by dose content uniformity over a range of temperatures. Standard physicochemical characteristics were also investigated using scanning electron microscopy, thermo analysis and laser diffraction techniques.

Key findings

The formulation had a relatively high fine particle fraction (47%) and produced a particle size distribution suitable for inhalation drug delivery. Particles had an irregular morphology and were predominately amorphous. Furthermore, the short-term stability showed the formulation to be stable from 4 to 37°C.

Conclusions

This study demonstrated the feasibility of formulating a solution-based pMDI containing CLA for the treatment of lung inflammatory diseases.
Exploratory Study of Physicochemical, Textural and Sensory Characteristics of Sugar‐Free Traditional Plum Jams
Authors: Culetu A. , Manolache F.A. , Duta D.E.
Published: December 2013

The present study is an exploratory research conducted with the aim of identifying correlations between physicochemical characteristics, textural parameters (firmness, cohesiveness, adhesiveness and chewiness) and sensory attributes evaluated by trained panel and consumers. A qualitative study was conducted on eight sugar‐free traditional plum jam samples differing in plum species, geographical area and processing technique. Good correlation was found between the physicochemical indices and sensory attributes as well as between texture parameters and sensory scores. The electronic nose system was used as a valuable tool for discriminating the samples. The most preferred sample (overall acceptability of 7.07 on a scale from 1 to 9) was a certified traditional product obtained from the household, boiled in a pot on direct fire. It had a good taste, a moderate degree of sweetness, a very dark color, a moderate degree of sourness, a good balance of sweet and sour, a very hard consistency and a persistent flavor after eating.

Practical Applications

This study aimed to find correlations between the physicochemical–textural–sensory characteristics of sugar‐free plum jams. This may be helpful for the industry to understand the consumers' preferences, to manufacture traditional food products and to control the quality.
Acute scrotum in Kawasaki disease: Two case reports and a literature review
Authors: Jibiki Toshiaki , Sakai Takehiko , Saitou Takeshi , Kanazawa Masaki , Ide Tomoyuki , Fujita Mayuko , Iida Yukiko , Yamazaki Sayaka , Ishiwada Fumie , Sato Junichi
Published: December 2013

Acute scrotum is a rare complication of acute Kawasaki disease (KD), less well recognized than other disease manifestations. We describe the cases of two patients, aged 59 months and 19 months, with hydrocele testis in the acute phase of KD. Scrotal ultrasound and trans‐illumination were used in the diagnosis of hydrocele testis. One patient underwent eventual surgical intervention. We reviewed the literature for a better understanding of the pathogenesis of scrotal symptoms in acute KD and investigated the clinical importance of hydrocele testis. Careful further clinical observation may elucidate the true incidence of this extracardiac symptoms, thereby clarifying the diagnostic value of this possible complication in acute KD.
Decreased sialylation of IgA1 O‐glycans associated with pneumococcal hemolytic uremic syndrome
Authors: Aoki Hisaaki , Shiomi Masashi , Ikeda Tae , Ishii Tsubura , Shimizu Nobuhiko , Togawa Masao , Okamoto Nobuhiko , Kadoya Machiko , Wada Yoshinao
Published: December 2013

Hemolytic uremic syndrome (HUS) in children is usually caused by Shiga‐like toxin‐producing Escherichia coli, but approximately 5% of cases are caused by invasive pneumococcal infection (P‐HUS). Reported herein is the case of a 9‐month‐old HUS patient with pneumococcal meningitis who needed hemodialysis for 12 days. Decreased sialylation was characterized in both transferrin N‐glycans and IgA1 O‐glycans, analyzed in the acute phase on mass spectrometry, consistent with S. pneumonia‐produced sialidases hydrolyzing both α2,3‐ and α2,6‐linked sialic acids. The method will complement the T‐antigen activation test and help to understand the molecular pathology related to P‐HUS.
Asymptomatic methylmalonic acidemia in a homozygous MUT mutation (p.P86L)
Authors: Underhill Hunter R , Hahn Si Houn , Hale Susan L , Merritt J Lawrence
Published: December 2013

Deficiency in methylmalonyl‐coenzyme A mutase (MCM) is associated with accumulation of methylmalonic acid (MMA) and clinical outcomes that include early death and neurological impairment. Reported here are two unrelated patients with a homozygous p.P86L mutation in the MUT gene, which encodes MCM, diagnosed following newborn screening. This is the first description of a homozygous mutation in the N‐terminal extended segment of the MCM apoenzyme. Both in vitro and in vivo testing did not find a response to supplemental hydroxocobalamin. After discontinuation of hydroxocobalamin in one patient, serum MMA level remained elevated but stable, while urine MMA increased. Both patients have remained asymptomatic with normal development. The observed homozygous p.P86L mutation in the N‐terminal extended segment may yield reduced MCM activity and is refractory to hydroxocobalamin supplementation, while not inducing a metabolically unstable phenotype. These genotype–phenotype associations further enhance the understanding of methylmalonic acidemia, which will continue to improve patient care.
Remarkably delayed occurrence of normal surfactant composition in an extremely preterm infant
Authors: Nakamura Toshihiko , Shimizu Hiroshi , Nishitani Chiaki , Yoshioka Toshiro
Published: December 2013

Reported herein is the first case of a remarkably delayed occurrence of normal surfactant composition in an extremely preterm infant who required a total of 15 doses of artificial pulmonary surfactant (Surfacten®). A male infant, born at 26 weeks gestation, developed respiratory distress at birth. Chest radiography was consistent with respiratory distress syndrome. The infant required repeated doses of surfactant, each resulting in transient periods of decreased ventilator requirement and improved blood gas values. Surfactant proteins (SP)‐A, SP‐B, SP‐C, and SP‐D from tracheal aspirate samples were analyzed on the 13th day (deterioration period) and 36th day (recovery period) after birth. On the 13th day sufficient SP‐A and SP‐D but no SP‐B no SP‐C were detected on western blot analysis. SP‐B and SP‐C were eventually detected on the 36th day. This infant therefore required almost 3 months to achieve normal surfactant function.
Counting platelets at transfusion threshold levels: impact on the decision to transfuse. A BEST Collaborative ‐ UK NEQAS(H) International Exercise
Authors: Lozano M. , Mahon A. , van der Meer P. F. , Stanworth S. , Cid J. , Devine D. , Fung M. K. , de la Salle B. , Heddle N. M. ,   on behalf of Biomedical Excellence for Safer Transfusion (BEST) Collaborative
Published: December 2013

Background and Objectives

Obtaining accurate and precise platelet enumeration in automatic platelet analysers at low platelet counts is a challenge. To explore the performance of current haematology analysers in counting platelet concentrations usually used as platelet transfusion threshold.

Material and Methods

An international exercise where four blood samples with platelet levels near usual platelet transfusion thresholds was prepared and distributed.

Results

The samples shipped had a platelet count of 6·3, 13·3, 21·6 and 53·0 × 109/l according to the international reference method. We received 82 sets of results from nine countries. Instruments from six different manufacturers were represented. Although the mean count for each of the four samples was very similar to the values, according to the reference method (9·0, 16·2, 23·0 and 57·6 × 109/l), significant variability in the results was found. Assuming that these were patient samples and the result of the count used to indicate a prophylactic platelet transfusion, undertransfusion would have occurred for 24·5% of the LP1 samples at a transfusion threshold of 10 × 109/l and, at a threshold of 20 × 109/l, undertransfusion would have occurred for 7·2% of the LP1 and 16·2% of the LP2 samples and overtransfusion would have occurred with 23·1% of the LP3 samples.

Conclusion

The results suggest that significant inaccuracy exists in counting low levels of platelets and that this inaccuracy might have a significant impact in under‐ and overtransfusion of platelet concentrates to patients.
The effect of timing of gamma‐irradiation on hemolysis and potassium release in leukoreduced red cell concentrates stored in SAGM
Authors: Serrano K. , Chen D. , Hansen A. L. , Levin E. , Turner T. R. , Kurach J. D. R. , Acker J. P. , Devine D. V.
Published: December 2013

While irradiation of red cell concentrates (RCC) prevents graft‐versus‐host disease in susceptible transfusion recipients, it also damages red blood cells (RBC). To understand the ability of irradiation regulations to prevent transfusion of inferior units, we irradiated 980 RCC in saline‐adenine‐glucose‐mannitol (SAGM) using various combinations of pre‐irradiation age and post‐irradiation storage times, and measured hemolysis and extracellular potassium levels. We observed unacceptably high hemolysis (>0·8%) in some RCC and elevated extracellular potassium levels in all gamma‐irradiated RCC. This suggests that more restrictive storage times should be considered for RCC in SAGM.
A Numerical Model to Study the Effects of Aluminum Foam Filler on the Dynamic Behavior of a Steel Tubular Energy Absorber Using a Multi-Node Displacement Evaluation Procedure
Authors: Veloso Vinícius , Almeida Magalhães Pedro Américo , Landre Janes
Published: December 2013

Tubular energy absorbers are usually found in the structures of cars, trains, and other means of transportation. They can absorb high levels of impact energy by plastic deformation during axial folding. The key advantages of this type of energy absorber are the compact dimensions, simple manufacturing, and good energy absorption efficiency. The dynamic behavior of the tube during collapse has a great influence on the total energy absorbed and, consequently, the force transmitted during folding. The optimization of this process may lead to improved energy absorption efficiency, allowing us to reduce the dimensions and costs of the component or improve the crashworthiness of pre-existing structures. Foam materials are used in most applications to improve the impact absorption of structures due to its constant load pattern during crushing. They are used, in most cases, as fillers inside empty absorbers such as tubes. In this paper, a numerical model was developed in order to study the possible interactions of foam and tube walls, providing information onhow this relation can influence the deformation modes of the tube. The obtained results showed a direct influence of the foam interaction with the tube walls under the energy absorption and load transmitting characteristics of the component.
Understanding Tow Tank Measurements of Total Drag for Long Thin Circular Cylinders
Authors: Jordan Stephen A.
Published: December 2013

Both the experimental measurements and numerical computations tell us that thin circular cylinders own turbulent boundary layer (TBL) characteristics which are dissimilar from planar geometries once the TBL thickness (δ) exceeds the cylinder radius. But the exceedingly long cylinders that serve as acoustic array systems have resorted to tow tank measurements due to the experimental complexities of axial sag or the required simplifications for efficient predictions. One key measurement in the tow tank experiments is the total drag, where the respective average tangential coefficients have been assessed relative to various scaled cylinder lengths, such as the length-based Reynolds number. We now know that the skin friction whose axial summation provides the total drag is governed by the radius-based Reynolds number as well. Herein, we revisit the many tow tank experiments to isolate the measurement discrepancies attributed to these two distinct Reynolds numbers. Once separated, these measurements provide a vital answer to the transformation of the TBL spatial growth to a temporal one (no additional net δ growth). This final stage is readily identifiable by a streamwise constant skin friction as given by near-wall flow homogeneity. This understanding lends subsequent evaluation of the TBL momentum thickness at the cylinder trailing edge. The present process involves applying several semiempirical expressions formed from the experimental and numerical evidence that supply the spatially evolving TBL characteristics along thin cylinders. Besides gaining an enhanced understanding of the TBL behavior, these semiempirical expressions are further clarified to form a final set that are helpful for design engineers of tow array devices in the military and oceanographic communities.
Nonlinear Dynamics of the Rod-Fastened Jeffcott Rotor
Authors: Yuan Qi , Gao Jin , Li Pu
Published: December 2013

Rod-fastened rotors are composed of some disks clamped together by a central tie rod or several tie rods distributed along the circumference. Due to the nonlinear flexural stiffness of the contact interfaces in disks, especially when the contact surfaces are partially separated, the dynamics of the rod-fastened rotors are potentially different from that of the solid rotors. In this paper, the nonlinear flexural stiffness of a rod-fastened Jeffcott rotor is calculated by the finite element method (FEM). Then the harmonic balance method is adopted to analyze the dynamics of the rotor. The flexural stiffness of a rod-fastened Jeffcott rotor dramatically decreased with the increase of the dimensionless load γ1 from 1 to 2.5. Thus, the dynamics of the rotor were nonlinear when it was subjected to a large unbalance force. The response of the rotating rotor contains a predominantly forward 1X component or both forward 1X component and backward 1X components. However, the rotor may settle in a state depending upon both the operating parameters and its history.
Optimal Lumped Mass Matrices by Minimization of Modal Errors for Beam Elements
Authors: Zuo Zhanxuan , Li Shuang , Zhai Changhai , Xie Lili
Published: December 2013

This paper clarifies the reason why error occurs in the mass lumping procedure and presents a new approach to construct lumped mass matrices for Euler–Bernoulli beam elements, which contain both translational and rotational degrees of freedom. Lumped mass matrices provide the proper translational inertia but change the rotational inertia compared with the continuous mass representation. Therefore, the optimal lumped mass matrices are expressed through the adoption of a variable rotational inertia parameter to counterbalance the decreased or increased rotational inertia. The goal of this study is to propose lumped mass matrices to minimize the modal error for beam elements. The accuracy of the new mass matrices is validated by a number of numerical tests.
Profile Design and Multifidelity Optimization of Solid Rocket Motor Nozzle
Authors: Yu Kuahai , Yang Xi , Mo Zhan
Published: December 2013

This paper presents a new profile modeling method and multifidelity optimization procedure for the solid rocket motor contoured nozzle design. Two quartic splines are proposed to construct the nozzle divergent section profile, and the coefficients of the splines' functions are calculated by a fortran program. Two-dimensional axisymmetric and three-dimensional compressible Navier–Stokes equations with Re-Normalisation Group (RNG) k-ε turbulent models solve the flow field as low- and high-fidelity models, respectively. An optimal Latin hypercube sampling method produces the sampling points, and Kriging functions establish the surrogate model combining with the low- and high-fidelity models. Finally, the adaptive simulated annealing algorithm is selected to complete the profile optimization, with the objectives of maximizing the thrust and the total pressure recovery coefficient. The optimization improves the thrust by 4.27%, and enhances the recovery coefficient by 4.63%. The result shows the proposed profile modeling method is feasible and effective to enhance the nozzle performance. The multifidelity optimization strategy is valid for improving the computational efficiency.
Experimental Study of Rimming Flows of Two Liquids in a Partially Filled Horizontally Rotating Cylinder
Authors: Becker Adam , aus der Wiesche Stefan
Published: December 2013

An experimental study was carried out to examine the flow patterns and the stability of rimming flows of two liquids in partially-filled horizontally rotating cylinders. Pure water and oil were considered as non-miscible liquids; the third phase in the cylinder was normal air. The effect of cylinder aspect ratio (length to diameter) was investigated, too. Significant mixing and de-mixing phenomena were observed between both liquids, and interesting transition processes occurred in the rotating multi-phase flow. The liquid configuration and flow characteristics were systematically visualized, and the resulting vibration spectra and Campbell diagrams were also obtained. It was found that the existence of a special sub-synchronous vibration was intimately connected with the transition to the rimming flow state. In contrast to the simple expectation, the experimental results indicated that non-trivial turbulent flow was present in the liquid domain even in case of the rimming flow state for high running speed. This is fully in contrast to the common assumption of a primary rigid-body motion of the liquid at this running speed level.
Numerical Approximation of Fluid Structure Interaction (FSI) Problem
Authors: Ebna Hai Bhuiyan Shameem Mahmood
Published: December 2013

Nowadays, advanced composite materials such as carbon fiber reinforced plastics (CFRP) are being applied to many aircraft structures in order to improve performance and reduce weight. Most composites have strong, stiff fibres in a matrix which is weaker and less stiff. However, aircraft wings can break due to Fluid-Structure Interaction (FSI) oscillations or material fatigue. The airflow around an airplane wing causes the wing to deform, while a wing deformation causes a change in the air pattern around it. Due to thrust force, turbulent flow and high speed, fluid-structure interaction (FSI) is very important and arouses complex mechanical effects. Due to the non-linear properties of fluids and solids as well as the shape of the structures, only numerical approaches can be used to solve such problems. The principal aim of this research is to explore and understand the behaviour of the fluid-structure interaction during the impact of a deformable material (e.g. an aircraft wing) on air. This project focuses on the analysis of Navier-Stokes and elastodynamic equations in the arbitrary Lagrangian-Eulerian (ALE) frameworks in order to numerically simulate the FSI effect on a double wedge airfoil. Since analytical solutions are only available in special cases, the equation needs to be solved by numerical methods. Of all methods, the finite element method was chosen due to its special characteristics and for its implementation, the software package DOpElib.
Computational Fluid Dynamics Analysis of Towed-Water Power Generators
Authors: Spall Robert , Maughan Robert , Phillips Warren
Published: December 2013

Towed-water power generators are used in long-distance sailing to generate power for charging battery banks. A basic configuration consists of a spinning turbine (propeller) towed behind the boat and attached to an alternator or generator via a torque line. In the present work, a series of seven inch diameter, six inch pitch turbines were tested both on the water and using computational fluid dynamics techniques. Turbine rotation rates for both an alternator and generator charging a 12V, 80 AH battery were measured for the on-water tests at a nominal towing speed of 3 m/s. Turbine torque vs. rotation rate results obtained by solving the Reynolds-averaged Navier-Stokes equations were plotted against generator and alternator torque curves to predict operating rotations per minute and associated power generation. Predicted rotation rate results were in reasonable agreement with those measured on the water.
Parametric Study on Aerodynamic Performance of a Centrifugal Fan With Additionally Installed Splitter Blades
Authors: Heo Man-Woong , Kim Jin-Hyuk , Cha Kyung-Hun , Kim Kwang-Yong
Published: December 2013

Aerodynamic Performance of a centrifugal fan with additionally installed splitter blades in the impeller has been investigated numerically using three-dimensional Reynolds-averaged Navier-Stokes equations. The shear stress transport turbulence model and hexahedral grids system were used to analyze the flow in the centrifugal fan. From results of the flow analysis, considerable energy loss by flow separation was observed in the blade passages. Splitter blades were applied between the main blades to reduce the loss and enhance fan performance. The chord length ratio of splitter to main blade, the angle between splitter and main blade, and the height ratio of outlet and inlet of impeller were selected as the geometric parameters, and their effects on the aerodynamic performance of the centrifugal fan have been investigated. The performance of the centrifugal fan with added splitter blades was improved conspicuously compared to the centrifugal fan without splitter blades. It was found that the installation of splitter blades in the impeller is effective to improve the aerodynamic performance of a centrifugal fan by reducing the flow separation generated between main blades in the impeller.
Numerical Study of Winglet at Low Reynolds Numbers
Authors: Pooladsanj Sina , Tadjfar Mehran
Published: December 2013

A numerical study has been performed to evaluate the aerodynamics coefficients of a winglet in the range of Reynolds numbers below 30,000. In this study some parameters on winglet design have been considered. The effect of winglet-tip airfoil thickness has been investigated on aerodynamics coefficients. In order to explore this effect, two different airfoils (NACA0002 and NACA0012) were employed at the winglet-tip. The influence of varying the winglet connection angle to the wing on aerodynamics coefficients and flow field characteristics in the vortex flow zone such as; circulation magnitude and vorticity magnitude in the vortex core have been studied. Six connection angles including 20°, 30°, 40°, 50°, 60° and 70° have been studied. Negative values of these angles have also been considered. In addition, the effect of changing wing aspect ratio on aerodynamics coefficients has been investigated. To solve the flow field around the studied geometry a fully structured grid was used which consists of 84 blocks.
Measurements in the Wake of a Ventilated Hydrofoil
Authors: Lee Seung-Jae , Kawakami Ellison , Arndt Roger E. A.
Published: December 2013

The purpose of this study is to develop the necessary algorithms to determine the bubble size distribution and velocity in the wake of a ventilated or cavitating hydrofoil utilizing background illumination. A simplified experiment was carried out to validate the automatic bubble detection algorithm at Saint Anthony Falls Laboratory (SAFL) of the University of Minnesota. The experiment was conducted in the high-speed water tunnel. First, particle shadow velocimetry (PSV) images of a bubbly flow were collected. All parts of the image that are above the global threshold are segmented by an edge detection method based on the Canny algorithm. The utilized algorithm was made to detect partly overlapping bubbles and reconstruct missing parts. After all images have been analyzed, the bubble velocity can be determined by applying a tracking algorithm. This study has shown that the algorithm enables reliable analysis of irregularly shaped bubbles even when bubbles are highly overlapped in the wake of the ventilated hydrofoil. It is expected that this technique can be used to determine the bubble velocity field as well as the bubble size distributions.
Characteristics of Ventilated Supercavities in a Periodic Gust Flow
Authors: Lee Seung-Jae , Kawakami Ellison , Arndt Roger E. A.
Published: December 2013

A ventilated supercavity consists of a large gas-filled bubble enveloped around an underwater vehicle that allows for significant drag reduction and an increase in maximum vehicle speed. Previous studies at the Saint Anthony Falls Laboratory (SAFL) of the University of Minnesota focused on the behavior of ventilated supercavities in steady horizontal flows. In open waters, vehicles can encounter unsteady flows, especially when traveling near the surface, under waves. In supercavitation technology, it is critical that the vehicle remains within the cavity while traveling through water to avoid unwanted planing forces. A study has been carried out in the high speed water tunnel to investigate the effects of unsteady flow on axisymmetric, ventilated supercavities. An attempt is made to duplicate sea states seen in open waters. In an effort to track cavity dimensions throughout a wave cycle, an automated cavity tracking script has been developed. Using a high speed camera and the proper software, it is possible to synchronize cavity dimensions with pressure measurements taken inside the cavity. Results regarding supercavity appearance, cavitation parameters and their relation to sea state conditions are presented. It was found that flow unsteadiness caused a decrease in the overall length of the supercavity while having only a minimal effect on the maximum diameter.
Calculation of Aerodynamic Noise for Centrifugal Fan of Air-Conditioner
Authors: Iwase Taku , Obara Hideshi , Yoneyama Hiroyasu , Yamade Yoshinobu , Kato Chisachi
Published: December 2013

Flow fields in a centrifugal fan for an indoor unit of an air-conditioner were calculated with finite element method-based large eddy simulation (LES) with the aim of predicting fan performance and aerodynamic noise in this study. The numerical simulation code employed throughout the LES was called FrontFlow/blue (FFB). We compared 10M grid [coarse grid] and 60M grid [fine grid] calculation results for investigation of influence of grid resolution. In the fine grid, the number of grid elements in blade-to-blade direction, and of region between the shroud and the bell mouth increased in particular. By calculating with the fine grid, calculated distributions of absolute velocities at blade exit reasonably agreed with experimental results. Because of this, maximum absolute velocity by fine grid near hub decreased as compared to those by coarse grid. Calculated sound pressure level by fine grid was therefore smaller than that by coarse grid, and the overestimation of sound pressure was suppressed by calculating with fine grid. This decrease of the absolute velocity was a first factor for the improvement of calculation accuracy. Moreover, number of captured streaks on the blade, hub, and shroud surfaces by fine grid increased as compared to those by coarse grid. As a result, size of streak by fine grid became smaller than that by coarse grid. Static pressure fluctuations by fine grid on the blade, hub, and shroud surfaces therefore reduced as compared to those by coarse grid. Aerodynamic noise was related to static pressure fluctuations according to Curle’s equation. This reduction of static pressure fluctuations was therefore a second factor for improvement of calculation accuracy.
Numerical Flow Simulation and Validation of an Electrical Submersible Pump
Authors: Rutter Risa , Sheth Ketan , O’Bryan Roshani
Published: December 2013

Computational Fluid Dynamics (CFD) is used to investigate the hydraulic performance of a centrifugal pump within the electrical submersible pump (ESP) unit in single-phase flow. The geometry consists of a three-stage centrifugal pump with an impeller and a diffuser in each stage. The stage performance is influenced by the inlet and outlet conditions of the stage, and therefore, three stages were modeled. The simulations were run at 3,500 RPM for various flow rates within the operating range. The k-ε turbulence model and the shear stress transport (SST) turbulence model were used to compare the capabilities of the model on performance predictions. Simulations were run in steady and unsteady flow conditions with a single vane and a full pitch model.

Hydraulic performance such as efficiency, pump head, and break horse power (BHP) obtained from numerical analysis were compared with the test results to validate the CFD model. The comparison results revealed that the CFD overpredicts the pump head and underpredicts the BHP by 5 to 10%. The discrepancy between measurements and predictions are reasonable because the hydraulic leakage and bearing power losses are not modeled in CFD. The overall predicted efficiency is higher than the measurements because of overpredicted head and underpredicted BHP. Comparing numerical simulations with different turbulent models showed no significant difference between the k-ε model and the SST model. The steady/ unsteady flow comparison also showed similarity in the hydraulic performance near the best efficiency point. For design purposes, steady flow simulation with a single vane and the k-ε model were used to cut computational time.
Optimized Chaotic Heat Exchanger Configurations for Process Industry: A Numerical Study
Authors: Ghanem Akram , Lemenand Thierry , Della Valle Dominique , Peerhossaini Hassan
Published: December 2013

A numerical investigation of chaotic laminar flow and heat transfer in isothermal-wall square-channel configurations is presented. The computations, based on a finite-volume method with the SIMPLEC algorithm, are conducted in terms of Péclet numbers ranging from 7 to 7×105. The geometries, based on the split-and-recombine (SAR) principle, are first proposed for micromixing purposes, and are then optimized and scaled up to three-dimensional minichannels with 3-mm sides that are capable of handling industrial fluid manipulation processes. The aim is to assess the feasibility of this mass- and heat-transfer technique for out-of-laboratory commercial applications and to compare different configurations from a process intensification point of view. The effects of the geometry on heat transfer and flow characteristics are examined. Results show that the flux recombination phenomenon mimicking the baker’s transform in the SAR-1 and SAR-2 configurations produces chaotic structures and promotes mass transfer. This phenomenon also accounts for higher convective heat transfer exemplified by increased values of the Nusselt number compared to the chaotic continuous-flow configuration and the baseline plain square-duct geometry. Energy expenditures are explored and the overall heat transfer enhancement factor for equal pumping power is calculated. The SAR-2 configuration reveals superior heat-transfer characteristics, enhancing the global gain by up to 17-fold over the plain duct heat exchanger.
Experimental Investigation of Wellhead PCP for Gas Well Deliquification
Authors: Morrison Gerald , Glier Michael , Narayanan Shankar , Xu Jun , Scott Stuart , Mirza Kamran
Published: December 2013

A Progressive Cavity Pump (PCP) was evaluated for use as a multiphase pump. The pump is a 576 gpm, constant wall thickness PCP operating with an air/water mixture. Thermocouples were installed along the length of the pump to monitor the elastomer temperature to determine when excessive temperatures were present. Inlet pressures of 15, 30, and 45 psig were considered with pressure rises of 30, 60, 90, 120, and 150 psig. The GVF’s considered were 20, 40, 60, 90, and 98%. It was determined that with the water and air mixture, 98% was the maximum GVF at which the pump could operate continuously. The volumetric efficiency, pump effectiveness, and mechanical efficiency were calculated. The temperature rise across the pump was small, so an isothermal flow was assumed. The PCP investigated has a steel rotor and an elastomer stator that were manufactured with an interference fit. This resulted in volumetric efficiencies above 95% for all test conditions at full speed. This interference fit produces a significant drag on the rotor which is relatively constant at a given speed over the entire operating range considered. This results in the mechanical efficiency being low, 15 to 20%, for ΔP = 30 psig but approaching 60% at ΔP = 150 psi for 0% GVF. The mechanical efficiency decreased with increasing GVF to a low of 28% at ΔP = 150 psi for 98% GVF. The GVF specified here is the actual GVF passing through the pump. If a liquid recirculation system were added to the pump reducing the GVF in the pump, higher efficiencies and the ability to operate at 100% GVF for the process fluid entering the pump system can be obtained.
Effects of Diffuser Vane Geometries on Compressor Performance and Noise Characteristics in a Centrifugal Compressor
Authors: Morita Yohei , Fujisawa Nobumichi , Goto Takashi , Ohta Yutaka
Published: December 2013

The effects of the diffuser vane geometries on the compressor performance and noise characteristics of a centrifugal compressor equipped with vaned diffusers were investigated by experiments and numerical techniques. Because we were focusing attention on the geometries of the diffuser vane’s leading edge, diffuser vanes with various leading edge geometries were installed in a vaned diffuser. A tapered diffuser vane with the tapered portion near the leading edge of the diffuser’s hub-side could remarkably reduce both the discrete frequency noise level and broadband noise level. In particular, a hub-side tapered diffuser vane with a taper on only the hub-side could suppress the development of the leading edge vortex (LEV) near the shroud side of the diffuser vane and effectively enhanced the compressor performance.
CFD Simulation of Water Flow Mixing With Discrete Phase in a Pump
Authors: Strongin Mikhail P.
Published: December 2013

The mixing process is very common in many industrial applications. In some cases, two or more liquids or discrete phase (DP) set on the pump inlet. Liquid mixture is often occurred in sanitation and agriculture applications and mixture of water with DP (such as sand) are met in the case of water transportation from natural sources (rivers, wells, etc.). DP distribution in the centrifugal pump is the subject of this study. Full pump geometry is considered, due to unsymmetrical nature of volute of the pump.

Turbulence k-ε closure model and Lagrangian discrete phase model has been used for most simulations.

It was found that smaller particles trap inside the pump for longer time than larger ones. The distribution of the bigger diameter particles on the outlet is more asymmetrical in comparison with particles of smaller diameter. Relatively large areas with very small particle concentrations can be observed. Particle distribution on the outlet for lighter particles demonstrates more uniformity.
A 1-D and 2-D Coupled Sediment Transport Model Using the Immersed-Boundary Method
Authors: Zhang Ning , Bolton Johnathan , Li Puxuan
Published: December 2013

Implementing small-scale rivers and channels within large-scale background sediment transport simulation is challenging because of the significant resolution difference. The modeling requires coupling between the background model and 1-D channel model. Based on a previously developed coupling method for hydrodynamic simulation, in this paper, a novel immersed-boundary (IB) type coupling method is developed and implemented for the sediment transport simulation. This coupling method enables dynamic linking between the channel and background with a relatively simple manner, and improves the efficiency and accuracy of the sediment transport simulation as water exchanges between the channel and background occur during a flooding event.
Viscosity and Friction Factor of Aluminum Oxide-Water Nanofluid Flow in Circular Tubes
Authors: Tang Clement C. , Tiwari Sanjib , Cox Matthew W.
Published: December 2013

Experiments have been conducted to characterize the viscosity and friction factor of aluminum oxide (Al2O3) nanoparticle dispersions at 6% vol. in water. Rheological characterization of the Al2O3 nanofluid has shown that it exhibits a Newtonian fluid behavior for the shear rate range of 6 to 122 s−1 between 6 and 75°C. Friction factor results of the nanofluid flowing through circular tubes of 1 m in length with different inner tube diameters (2.97 and 4.45 mm) were experimentally measured in the laminar and the onset of transition regions. The experimental results from this study indicate that, when the nanofluid properties are properly characterized, the friction factors of the Al2O3 nanofluid are largely in agreement with classical friction factor theory for single-phase flow.
Fundamental Study on Oil Mist Separation in Swirl Flow
Authors: Ito Yuhei , Hiwata Akira , Sato Kotaro
Published: December 2013

Recently, the rotation rates used in fluid machines have been increasing as such machines continue to be downsized. However, these high rotation rates lead to the possibility of lubricant oil mist formed inside the compressor becoming mixed with the refrigerant gas, which can lead to a decrease in the heat exchange efficiency. The present study attempted to clarify the separation mechanism for refrigerant gas-lubricant oil mist two-phase flow during swirl flow in order to improve the oil mist separation efficiency. Both experiments and numerical simulations were carried out to investigate the relation between the oil mist separation efficiency and the flow characteristics in a test chamber containing a rotor. It was found that the flow characteristics were determined by the swirl number Sw, and the flow pattern was quite different for Sw = 1.0, 1.5 and 3.0. In addition, the oil mist separation efficiency increased with Sw and also showed a dependence on the chamber aspect ratio. The centrifugal force acting on a virtual particle in the chamber was also evaluated under various conditions.
Development of a Capacitance Based Void Fraction Sensor for Two-Phase Flow Measurements
Authors: Hewlin Rodward L. , Kizito John P.
Published: December 2013

The aim of this paper was to develop a capacitance based sensor capable of measuring void fraction in a continuous two-phase flow field. The design methodology and operation of the capacitance based void fraction sensor is discussed. Two designs of capacitance void fraction sensors were developed and tested. Some of the problems associated with the first were identified and a new sensor electrode configuration was developed which presented a more sensitive and repeatable response. Data was collected covering a wide range of void fraction measurements ranging from 0 to 1 for water as the working fluid. Calibration of the sensor required that the air gap or void capacitance (dry signal) be measured followed by an increase in liquid levels (wet signal) to obtain a range of void fraction measurements for static calibration. The static calibration data obtained was nonlinear for the full range of void fraction measurements for water. This paper covers the design requirements, calibration procedure and static calibration data obtained for the developed sensor, and dynamic void fraction data measurements. The sensor was tested in both a horizontal and vertical orientation and proved to be orientation insensitive. The experimental results are promising for water and verify successful operation for measuring void fraction in continuous two-phase flows.
Touchpad in Education: Dynamic Learning Framework Assessment and Content Development for the Undergraduate Fluid Mechanics
Authors: Kumar V. , Ramana C. , Afrin S. , Ortega J. , Agarwal Neelam , Udoewa Victor
Published: December 2013

This paper presents a dynamic learning framework (DLF) based on dynamic course contents and assessment methods using latest web-based technologies with keeping in mind the recent advancement in touchpad computing devices (such as IPAD and Android based tablets). In the DLF framework, the effectiveness is assessed via evaluating the learning outcomes of increasing the learnability of high level concepts in the Bloom’s Taxonomy of cognitive learning. It proposes to address the challenges is creating a fluid mechanics module that incorporates all levels of the Bloom’s cognitive taxonomy. This is achieved via integration of mathematical, conceptual and visual contents. The lower level concepts (i.e., Remembering, Understanding, and Applying) are computerized and tested using Computer Adaptive Testing (CAT) algorithm. Our targeted audiences are from a predominantly Hispanic cultural setting and in undergraduate mechanical engineering courses. To capitalize on unique cultural setting and linguistic needs, the assessment is prepared in bi-lingual (Spanish and English) with localized problems. A pre-assessment of students’ learning styles was performed to assess their learning preference and the presentation was tuned to average audiences. It was observed that about 10% of the students used bi-lingual instructions in the exam which was conducted as an extra-credit option to paper based exam in order to assess the DLF framework. Students were also asked to contribute questions to generate a question database with localized problems.
Flow in a Human Renal Artery Network With a Saccular Aneurysm
Authors: Armstrong Grant , Peno Samantha , Espinoza Wendy , Judd Eric , Lemley Evan
Published: December 2013

Blood flow into the kidneys through the renal artery determines the systemic blood pressure which is regulated by the baroreceptors in the kidneys. When the baroreceptors sense decreases in local fluid pressure they stimulate the renin-angiotensin aldosterone (RAA) system, which increases systemic blood pressure by constricting blood vessels throughout the body.

An aneurysm in the renal artery leads to high systemic blood pressure in most patients with this condition, but the mechanisms by which the pressure increase occurs are not well understood. One explanation of the pressure increase could be a drop in local fluid pressure near the aneurysm itself causing the RAA system to “correct” this low pressure by systemically increasing the blood pressure.

The ongoing work reported here has focused on a model renal artery network with and without an aneurysm by simulating the flow with computational fluid dynamics (CFD) software. The fluid for the simulations was meant to mimic blood in terms of density and viscosity for shear stresses where Non-Newtonian flow effects should not be a concern. Flow into the renal artery was at a Reynolds number of almost 700, to mimic the flow rate in the renal artery. The simulations were performed to determine the difference in pressure between an inlet to the renal network and the exits from the network. These results indicate that the pressure difference through the network differed by less than 10 Pa comparing networks with and without saccular aneurysm. The pressure change that would trigger the RAA system is nearly 1000 Pa. So we conclude that the effect of changing the geometry with only a saccular aneurysm is not responsible for triggering the RAA system alone. Other effects that could lead to triggering of the RAA system are discussed as well as our initial construction of a system to perform validation experiments of our CFD results.