bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficacy and safety of elbasvir/grazoprevir for 8 or 12 weeks for hepatitis C virus genotype 4 infection: A randomized study
Authors: Asselah Tarik , Pol Stanislas , Hezode Christophe , Loustaud‐Ratti Veronique , Leroy Vincent , Ahmed Si Nafa Si , Ozenne Violaine , Bronowicki Jean‐Pierre , Larrey Dominique , Tran Albert , Alric Laurent , Nguyen‐Khac Eric , Robertson Michael N. , Hanna George J. , Brown Deborah , Asante‐Appiah Ernest , Su Feng‐Hsiu , Hwang Peggy , Hall Jessie Durrand , Guidoum Amir , Hagen Karin , Haber Barbara A. , Talwani Rohit , Serfaty Lawrence
Published: November 2019

Background & Aims

Hepatitis C virus (HCV) genotype (GT) 4 infection is prevalent in sub‐Saharan Africa and the Middle East, particularly in Egypt. This study evaluated the safety and efficacy of elbasvir/grazoprevir administered for 8 and 12 weeks in participants with HCV GT4 infection.

Methods

In this partially randomized, open‐label multicentre study conducted in France (NCT03111108; Protocol MK5172‐096), treatment‐naive participants with GT4 infection and F0‐F2 fibrosis were randomized 2:1 to elbasvir (50 mg)/grazoprevir (100 mg) for 8 or 12 weeks. Treatment‐naive participants with F3‐F4 fibrosis and all treatment‐experienced participants (F0‐F4) were assigned to elbasvir/grazoprevir for 12 weeks. The primary endpoint was sustained virologic response (SVR) 12 weeks after the end of therapy.

Results

One hundred and seventeen participants were enrolled. Among treatment‐naive participants with F0‐F2 fibrosis, SVR was achieved by 94% (50/53) and 96% (26/27) of those receiving elbasvir/grazoprevir for 8 or 12 weeks, respectively, and four participants relapsed. In the 12‐week arm, 95% (35/37) achieved SVR and two participants relapsed. NS5A resistance‐associated substitutions were present at baseline and virologic failure in five of the participants with relapse. Drug‐related adverse events occurred in 42% (n = 22) and 50% (n = 32) of participants receiving 8 and 12 weeks of treatment, respectively. No participant discontinued treatment owing to an adverse event.

Conclusion

These data confirm the efficacy of elbasvir/grazoprevir administered for 12 weeks in treatment‐experienced individuals with HCV GT4 infection and those with advanced fibrosis. Treatment‐naive individuals with mild fibrosis can be treated effectively with an 8‐week regimen.
Assessing the State of Mandatory Fees in America's Public Colleges and Universities: Causes and Consequences
Authors: Reinagel Tyler P. , Cooper Christopher A.
Published: November 2019

Objectives

Mandatory fees in American's public universities and colleges are ubiquitous. While many of these fees provide for essential university functions, others provide particularized benefits for small groups of students. Despite importance of the topic, we know very little about how universities assess fees.

Methods

In this article, we catalog every university fee at every U.S. public college and university during academic year 2014–2015 and conduct multivariate analysis to determine the conditions under which institutions assess more and higher fees.

Results

We discover considerable disparity in how fees are assessed. Both university characteristics and state policy affect the amount of fees that colleges and universities assess.

Conclusions

The heterogeneous assessment of university fees raises important questions about equity and responsiveness of public institutions.
The safety and efficacy of ferumoxytol in the treatment of iron deficiency: a systematic review and meta‐analysis
Authors: Abdulrehman Jameel , Tang Grace H. , Auerbach Michael , Santesso Nancy , Sholzberg Michelle
Published: November 2019

INTRODUCTION

Ferumoxytol is an intravenous (IV) iron formulation for treatment of iron deficiency (ID) that faced post‐marketing reports of serious adverse events (SAEs).

OBJECTIVES

To determine the safety and efficacy of ferumoxytol compared to other iron formulations and placebo.

METHODS

We searched the Cochrane Library, Medline, and EMBASE from inception until February 2018 as well as trial registries and reference lists of relevant articles for randomized or quasi‐randomized controlled trials.

RESULTS

The review included nine studies with 5691 participants. Studies were at low risk of bias.

When comparing ferumoxytol to other IV iron formulations, there is moderate quality evidence (QE) of little to no difference in treatment emergent adverse events (TEAEs) (risk ratio [RR] 0.88, 95% confidence interval [CI] 0.80‐0.97), treatment related adverse events (TRAEs) (RR 0.73, 95% CI 0.61‐0.88), SAEs (RR 1.13, 95% CI 0.77‐1.67), hypotension or hypersensitivity reactions (RR 0.58, 95% CI 0.31‐1.09), or composite cardiovascular outcomes (RR 0.56, 95% CI 0.24‐1.29), low QE of little to no difference in related SAEs (RR 0.55, 95% CI 0.05‐6.16), and high QE of little to no difference in the number of patients with an increase in hemoglobin by at least 1 g/dL (RR 1.04, 95% CI 0.96‐1.12).

Ferumoxytol had less TEAEs compared to oral iron (RR 0.78, 95% CI 0.61‐0.98), but more compared to placebo (RR 1.62, 95% CI 1.01‐2.61).

DISCUSSION

Ferumoxytol is as efficacious and safe as alternative IV iron formulations with no clear safety concerns.
Efficient Broadband Vibration Energy Harvesting Using Multiple Piezoelectric Bimorphs
Authors: Farokhi Hamed , Gholipour Alireza , Ghayesh Mergen H.
Published: November 2019

This paper presents complete nonlinear electromechanical models for energy harvesting devices consisting of multiple piezoelectric bimorphs (PBs) connected in parallel and series, for the first time. The proposed model is verified against available experimental results for a specific case. The piezoelectric and beam constitutive equations and different circuit equations are utilized to derive the complete nonlinear models for series and parallel connections of the PBs as well as those of piezoelectric layers in each bimorph, i.e., four nonlinear models in total. A multi-modal Galerkin approach is used to discretize these nonlinear electromechanical models. The resultant high-dimensional set of equations is solved utilizing a highly optimized and efficient numerical continuation code. Examining the system behavior shows that the optimum load resistance for an energy harvester array of 4 PBs connected in parallel is almost 4% of that for the case with PBs connected in series. It is shown an energy harvesting array of 8 PBs could reach a bandwidth of 14 Hz in low frequency range, i.e., 20–34 Hz. Compared with an energy harvester with 1 PB, it is shown that the bandwidth can be increased by more than 300% using 4 PBs and by more than 500% using 8 PBs. Additionally, the drawbacks of a multi-PB energy harvesting device are identified and design enhancements are proposed to improve the efficiency of the device.
Modeling Planar Joints With Clearance Between the Guide and Roller in Mechanisms
Authors: Gao Yunkai , Duan Yuexing , Yang James , Yuan Zhe , Ma Chao
Published: November 2019

In mechanisms, the guide and roller form joints with clearance and the roller may make contact with the convex surface or concave surface of the guide. Correctly modeling this type of joint is critical in a mechanism's dynamic performance analysis. This paper proposes a contact kinematic model and a hybrid contact force model for the planar joint and investigates both the convex and concave contact cases. The contact kinematic model is derived from the relative motion between the guide and roller and the hybrid contact force model consists of an elastic force and a damping force. The sliding door mechanism is used as an illustrative example to demonstrate the proposed models. Experimental data are collected for a vehicle's sliding door mechanism. Results show that the proposed models are effective and the simulation results match the general trend of experimental data based on RMS errors.
Fabrication and Multiphysics Modeling of MEMS Thermal Flow Sensor
Authors: Cable Justin , Anderson Kevin R.
Published: November 2019

A micromachined thermal flow sensor is presented demonstrating sensing liquid flow rates as low as 2 microliters per minute capable of being used for biomedical applications. These flow sensors rely on the varying electrical resistance of sensors generated by forced convection at different flow rates. The sensor array presented was constructed using microelectromechanical systems (MEMS) techniques including micro-molding, wet etching and dry etching utilizing biocompatible materials. A numerical model was built using COMSOL multi-physics in order to predict and optimize the electrical, thermal and fluid behavior of the sensor, which was verified with experimental data. The construction allowed for multiple thermal flow sensing operational modes. Here, constant current hot film and constant current calorimetric were simulated and tested. A variety of flow sensor geometries were compared to investigate maximum heat transfer to the sensors, thermal insultation, size, sensitivity and range capabilities. The sensor design is such that it is capable of detecting different flow direction and various flow ranges for different fluids. In addition to the performance capabilities outlined, the sensor is relatively inexpensive and should have a long lifetime due to the lack of moving parts.
Asymptotic Expansion Technique for Evaluating the Uncertainty of Moist-Air Density Formula
Authors: Chun Sejong
Published: November 2019

Asymptotic expansion technique can evaluate the measurement uncertainty by classifying an output quantity into a measured value and its correction values. The asymptotic expansion technique combines simultaneous observations of input quantities into the output measured value. The asymptotic expansion technique is useful in evaluating a multi-variate output quantity such as the moist-air density formula (CIPM-2007), in which covariances among input quantities could complicate the evaluation of measurement uncertainty.

This study demonstrates that both the Taylor’s series expansion and the chain rule of differentiation are enough to calculate the sensitivity coefficients for the CIPM-2007 air density formula. The measurement uncertainty is found to be greater than the original CIPM-2007 formula by two orders of magnitude. It is because the uncertainty of correction values come from a commercial instrument for monitoring laboratory environments. Nevertheless, the asymptotic expansion technique is useful for measurement uncertainty evaluation to avoid subtle problems of ignoring covariance of input quantities in the literature.
Calculation of the Flow Profile Correction Factor Based on Flow Velocity Distribution Functions for Ultrasonic Flow Metering
Authors: Chun Sejong
Published: November 2019

Transit-time ultrasonic flow metering relies on the flow profile correction factor (FPCF) to improve its measurement capability by converting line-integrated flow velocity into area-integrated flow velocity. It is because the flow velocity is integrated along ultrasonic paths between ultrasonic sensors by sending and receiving pulse signals in the transit-time ultrasonic flow metering. ISO 12242 (liquid flow metering) and ISO 17089 (gas flow metering) specify how to define the FPCF with a transit-time multi-path ultrasonic flow meter. The FPCF is applied to an averaged value of line-integrated flow velocities, not to each line-integrated flow velocity, according to the ISO standards. The present use of FPCF is validated in the fully-developed turbulent pipe flow, which a long straight pipe is installed upstream of the ultrasonic flow meter. However, the present FPCF would not be very accurate in asymmetric pipe flows with various conduit elements, such as elbows.

This study attempts to apply the FPCF to each line-integrated flow velocity in transit-time multi-path ultrasonic flow metering. The FPCF can be applied to each line-integrated flow velocity if the FPCF is based on flow velocity distribution functions, such as those suggested by Salami (1984). The Salami’s flow velocity distribution functions include one symmetric flow, three one-peak flows, and two two-peak flows. The FPCF is calculated by line-integrals along the ultrasonic paths on each flow velocity distribution function. This study is the first attempt to show that the FPCF can be applied to convert the line-integrated flow velocities into the area-integrated flow velocity along each ultrasonic path.
Numerical Simulation and Neural Network Study Using an Upstream Cylinder for Flow Control of an Airfoil
Authors: Zhang Meihua , Zheng Zhongquan Charlie , Liu Yangliu , Jiang Xiaoyu
Published: November 2019

Flow behaviors of a downstream object can be affected significantly by an upstream object in close proximity. This concept is used for flow control in this study to maximize the lift/drag ratio on a NACA0012 airfoil. A cylinder with cross-flow translational motion is placed upstream of the airfoil. Numerical simulations are carried out with an immersed-boundary method to solve the incompressible, viscous flow at the Reynolds number of 2000. Control parameters that influence the dynamics of flow around the airfoil are systematically investigated, including the oscillating frequency and amplitude of the upstream cylinder, the distances between the cylinder and the airfoil, and the diameter of the cylinder. To obtain sample data properly and efficiently for carrying out the neural network study, the idea of the orthogonal test method is used to set the control parameters in the numerical simulation. The combination of the back-propagation neural network algorithm and the genetic algorithm is applied to find the optimal value of the lift/drag ratio and the corresponding control parameters. The results show that when the cylinder oscillating frequency increases, the ratio increases until negative coefficients occur; when the distance between the cylinder and the airfoil increases or the amplitude of oscillating cylinder increases, the ratio decreases first and then increases; and when the cylinder diameter increases, the ratio increases. Compared to the reference case, the optimized lift/drag ratio increases 178%.
Tangential Wall Jet Flow and Gas Entrainment in Gas-Liquid Cylindrical Cyclone Compact Separator
Authors: Kolla Srinivas Swaroop , Mohan Ram S. , Shoham Ovadia
Published: November 2019

Gas Carry-Under (GCU) is one of the undesirable phenomena that exist in the Gas-Liquid Cylindrical Cyclone (GLCC) separators even within the liquid carry-over Operational Envelope (OE). In order to quantify the GCU, it is important to understand the cause of gas entrainment that occurs in the GLCC other than the incoming entrained gas within the liquid medium. The tangential inclined inlet of 27° with reduced area allows the stratified liquid flow to exit the inlet nozzle tangentially along the wall into the vertical lower part of the GLCC, whereby the liquid film spreads along the wall in an asymmetrical shape. The gas moves to the center of the GLCC and escapes through the gas leg. The liquid film flow is complex and turbulent exhibiting unevenness of the film thickness and asymmetrical velocity distribution. Experimental investigations show that the magnitude of liquid wall jet film tangential and axial velocity change as a function of length along the GLCC below the inlet of the GLCC. This wall jet film flowing down along the wall is the cause for gas entrainment and GCU. The experimental results show that the gas entrainment mechanism is not like the conventional jet entrainment as expected to be occurring in GLCC. The change in velocities of the wall jet film at various liquid heights maintained below the inlet results in varying gas entrainment at various inlet liquid levels and for fluid properties. The wall jet phenomena that takes places at the inlet has been discussed in detail and a mechanistic model capable of predicting the wall jet parameters has been presented in this paper. Further, a novel mechanistic model that is developed for the first time is also presented which can predict the gas entrainment at various liquid levels and flow conditions using the wall jet parameters as an input condition.
Unsteady Vortex Breakdown Phenomena in an Enclosed Cylindrical Container With a Rotating Endwall Disk
Authors: Nakatsuka Yuki , Iwatsu Reima , Hyun Jae Min , Koyama Hide S.
Published: November 2019

A high-quality precision-controlled turntable apparatus was fabricated to probe the dynamic behavior of a viscous fluid contained in a cylindrical container. Vortex breakdown(s) produced by a rotating endwall disk was visualized by using a fluorescent dye injection technique, and its flow field was measured by using a particle image velocimetry. This flow is characterized by two non-dimensional parameters, i.e., the height-to-radius ratio H/R and the rotating Reynolds number Re = Ω2/v. Limiting boundaries for single, double and triple vortex breakdowns in steady flow were re-plotted to compare with the previous visualization studies of Escudier. The locations of stagnation points of the vortex breakdown bubble(s) in steady flow were measured quantitatively. The overall experimental results in the steady flow were in excellent agreement with Escudier’s data. In unsteady flow, the amplitude and time period of periodic axial oscillation, and the polar angle and time period of precession, were measured. The domains for periodic axial oscillation and for precession in unsteady flow were delineated.
Effects of Coriolis Force on Turbulence Structure in Rotating Channels With High and Low Aspect Ratios
Authors: Koyama Hide S. , Tatsuta Shoichiro , Tamura Ema , Nigim Hani H.
Published: November 2019

To clarify the stabilization, destabilization and secondary flow effects of the Coriolis force on the turbulence structure in rotating channels with high and low aspect ratios, experimental investigations were undertaken by using a rotating wind tunnel about 2 meters in diameter. A hot-wire anemometer and more than 6 hot-wire probes with fine resistance wire, each inclined at a known angle to the main flow, were used for the measurements of time-mean velocities and 6 components of Reynolds normal and shear stresses. An optical transmission system of electrical signals from a rotating apparatus to the stationary system was used to immunize the electrical noise. The hot-wire probe was traversed with sufficient accuracy. Phenomena of the stratification, Taylor-Görtler type vortices in the destabilized nominal two-dimensional turbulent boundary layer, relaminarization from turbulent to laminar boundary layer in the high aspect ratio channel and a pair of longitudinal flat vortices in the low aspect ratio channel were observed, and discussed in detail by using the low of conservation of angular momentum, the vorticity transport equation and the Reynolds stress transport equations in a rotating frame.
Wake Behavior Around Flapping Wings of Model Hawkmoth Moving Sideways
Authors: Han Jong-Seob , Han Jae-Hung
Published: November 2019

This study investigated nearwake behaviors around flapping wings moving sideways. A dynamically scaled-up flapping manipulator was installed on a servo-driven towing carriage to give the sideways movement. In the single wing configuration, the wing in the windward side did not encounter any noticeable effects on the aerodynamic characteristics. The wing in the leeward side, on the other hand, experienced a substantial lift augmentation. We found a stretched leading-edge vortex (LEV) on the wing in the leeward side, implying the additional feeding flux into the LEV. In this case, the moving sideways gave a continuous lateral wind, which became the source to maintain the lift augmentation with the less downward component. We also found that the moving sideways rather intensified the interaction between the wake of the wing in the windward side and the contralateral wing, i.e., the wing-wake interaction. Accordingly, the lift augmentation on the wing in the leeward side practically disappeared by the wing-wake interaction. A digital particle image velocimetry for nearwake behaviors found the less developed trailing-edge shear layer and wingroot vortex traces. This implied that the massive downwash induced by the wing in the windward side was the main source to neutralize the lift augmentation on the contralateral wing.
Effects of Wind Environment on Propeller Performance of Multirotor Drone in Hover
Authors: Murakami Motonao , Abe Hiroyuki , Aono Hikaru , Ishikawa Hitoshi
Published: November 2019

The purpose of this study is to understand the effect of cross flow and fluctuating flow on the propeller performance of MAV. This study especially has focused on the propeller performance during hovering flight under several cross flow velocity in actual flight conditions. We investigated four test cases of propellers with different starting point of design. The thrust and the torque of each propeller were experimentally measured by using the force transducer in wind tunnel. Figure of Merit (FM) of each propeller were evaluated based on the thrust and the torque measurement. The results showed that low cross flow velocity reduced FM. However, high cross flow velocity improved FM. Fluctuating flow yielded the change of FM with time. Furthermore, it was found that the starting point of the propeller design had a great effect on FM under wind environments.
The Performance Enhancement of Hemodialyzers: Computational Fluid Dynamics Study
Authors: Alghafis Abdullah A. , Alshwairekh Ahmed M. , Alwatban Anas M. , Alqsair Umar F. , Oztekin Alparslan
Published: November 2019

Computational fluid dynamics simulations are conducted to study the hemodialysis process in separation modules containing hollow fiber membranes. Hemodialysis is the filtration process which removes waste out of the blood. In this work, three-dimensional steady-state laminar flow simulations are conducted to investigate the effect of disk baffles on the performance of the hemodialysis process. The uniformly spaced baffles are placed along the axis of the shell within the dialyzer. The disk baffles of diameter 2.85 dhd were considered, where dhd is the shell hydraulic diameter. The inlet solute mass fraction of the blood solution is fixed at 0.00074, while the inlet solute mass fraction of the dialysate solution varied as 0.004 and 0.007. The blood and the dialysate flow rates are fixed. Our results revealed that the presence of disk baffles in the shell mitigates the concentration polarization and yields higher urea permeation. The higher dialysate concentration solute yields a 41.2% increase in the urea permeate rate compared to the lower dialysate solute concentration.
Mitigation of Flow-Induced Pressure Fluctuations in a Francis Turbine Using Water Injection
Authors: Altimemy Muhannad , Attiya Bashar , Daskiran Cosan , Liu I-Han , Oztekin Alparslan
Published: November 2019

Computational fluid dynamics simulations are conducted to characterize the spatial and temporal characteristics of the turbulent flow fields inside Francis turbine operating at the design and partial load regimes. High-fidelity large eddy simulations turbulence model is applied to investigate the flow-induced vibrations in the draft tube of the unit. The water injection at 4% rate from the runner cone is implemented to control the flow-induced pressure fluctuations. The simulations are conducted at the turbine design point and two partial load operations with and without water injection. It has been demonstrated that the water injection has a profound influence in the turbulent flow structure and the pressure field inside the draft tube at the partial load operating conditions. To evaluate the effectiveness of the water injection techniques in mitigating flow-induced fluctuations, the probes at various locations along the wall of the draft tube are used to monitor the pressure signals. It appears to be a reduction in the level of pressure fluctuations by the water injection at both partial load operating regimes. However, we could not draw a firm conclusion about the level of mitigation of flow-induced vibrations. Simulations should be carried out for much longer flow time. Water injection hardly influenced the unit power generation. Hence water injection can be employed effectively without a major liability on the power generation.
Plasma Driven Shock Tube for Dynamic Characterization of Sensors
Authors: Bivolaru Daniel , Papadopoulos George
Published: November 2019

The development and evaluation of a small scale plasma driven shock tube is described in the current paper, as a new option to sensor characterization for dynamic flow measurements. The initiation of a high energy plasma discharge at one end of a quartz tube generates a shock wave that travels the length of the tube. The rate of shock generation is governed by the discharge energy and can easily be several tens of pulses per minute, instead of several pulses per day as with traditional diaphragm-based shock tubes. There is no contamination with solid particles at the test location, and rise times of the order of microseconds can be achieved. The energy release is controllable resulting in robust and repeatable operation. Lastly, the overall footprint of the plasma driven shock tube is small and ideal for frequent laboratory bench top operation.
Can Naturally Pulsating Prefilming Slurry Atomization Be Enhanced by Artificial External Modulation?
Authors: Strasser Wayne
Published: November 2019

Under certain conditions in preferred three-stream geometries, a non-Newtonian airblast atomization flowfield violently pulses (axially and radially) by self-generating and self-sustaining interfacial instability mechanisms. The pulsing is severe enough to send acoustic waves throughout feed piping networks. The most recent work on this system instructed that exothermic chemical reactions enhance this moderate Mach number atomization. Explored herein is the potential to further enhance reaction-assisted disintegration by independently superimposing both sinusoidal and randomized mass flow fluctuations of +/− 50% of the mean onto otherwise constant gas feed streams. Two nozzle geometries (low versus high prefilming distance) and multiple superimposed feed frequencies (ranging from below to above the naturally dominant tone) are considered for each gas stream, making twenty-one total long-running unsteady PLIC-VOF CFD models. Droplet size, plus nine other temporal measures, were considered for assessing atomizer performance in our energy production process. Results indicate that superimposed frequencies have potential to enhance chaotic atomization in a statistically significant manner. Depending on the geometry, the largest effect was about a 10% reduction in droplet size; however, some combinations experienced a droplet size increase. Only marginal differences were seen in the nine other measures, such as injector face heat exposure. In addition to the immediate industrial benefit from modulation, dramatic changes in acoustics were produced by imposed feed perturbations at frequencies lower than the natural tone. A detailed study of start-up flow reveals new mechanisms which explain performance differences.
Numerical Investigation of Pressure Pulsation in Vaneless Region of a High Speed Centrifugal Pump
Authors: Zeng Yongshun , Yang Min , Zhai Yuqing , Yao Zhifeng , Wang Fujun , Xiao Ruofu
Published: November 2019

The pressure pulsation due to rotor-stator interaction (RSI) is unavoidable for high-speed centrifugal pump when operating under different conditions. The frequency components of pressure pulsation in the vaneless region are the most complex, and the pressure pulsation characteristic plays an important role in pump structural stress analysis. A numerical simulation method is used to obtain the hydraulic performances of a high-speed centrifugal pump with 9857 r/min at the range of flow rates between 48.1 to 155.0 m3/h. The head and efficiency under different operating conditions have good agreement with experimental results, with maximum deviations in 3.82% and 5.37%, respectively. The results show that the level of the pressure pulsation from the inlet to the outlet of the impeller increased gradually, and the pressure pulsations between the short blades are greater than that between the long and short blades. In the diffuser, the pressure pulsation is the highest near the tongue, whereas it is lower in the region between the two tongues, and this region is defined as the vaneless region. The pressure contours in the vaneless region almost have no change, while they near the tongue are densely distributed, revealing the mechanism of uneven pressure pulsation distribution. Moreover, there is a high radial velocity distribution near the tongue in the vaneless region, indicating that there may be a jet-wake pattern occured in this region.
Hydrodynamic Performance and Appendage Considerations of Wave-Piercing Planing Craft Overlapping Waves and Porpoising
Authors: Kim Sang-Won , Lee Sang-Eui , Lee Gyoung-Woo , Seo Kwang-Cheol , Oshima Nobuyuki
Published: November 2019

This work addresses the numerical study of wave-piercing planing hull and related hydrodynamic performance as the appendages. From the half century ago, the interest in high-speed planing crafts has been advanced toward maintaining performance stably. The main reasons to make it hard are instability motion occurring from porpoising and wave condition. Porpoising is mainly due to overlap the heaving and pitching motion with certain period, which is caused by instable pressure distribution and changing longitudinal location of center of gravity. In addition, in wave condition, encountering wave disturbs going into planing mode. This paper presents numerical results of wave-piercing planing hull in porpoising and wave condition. Numerical simulation is conducted via Reynolds Averaged Navier-stokes (RANS) with moving mesh techniques (overset grid), performed at different wave condition. The results for the behaviors of wave-piercing hull form are practically presented and investigated in this study. The understanding of these phenomena is important for design of appendages of wave-piercing hull-form.
Suppression of the Surging Phenomenon by Modifying Tongue Shape of Air Conditioner Mounted With Cross-Flow Fan
Authors: Nukaga Haruki , Maita Hiroshi , Daisaka Hisashi
Published: November 2019

Energy saving of room air-conditioner (RAC) is strongly required due to growing environmental concern. It is difficult to work a cross flow fan (CFF) at the most efficient operating point (OP) because a surging phenomenon occurs near this efficient OP. The conventional method for suppressing the surging phenomenon by increasing a rotation speed is unfavorable because a fluidic noise and a fan power consumption increase. Therefore, we investigated the new method for suppressing the surging phenomenon focusing on a structure of a fan casing.

It is known that the surging phenomenon is likely to occur from both right and left ends of the CFF. However, an area where surging occurs and a flow pattern in this area have not been revealed in detail. In this study, we experimentally investigated the area where surging occurs by measuring the outlet air velocity distribution across the CFF. In addition, the flow pattern in this area was compared with that of the center area using simulation. Simulation results showed that an area ratio of a vortex flow inside the CFF is high at both ends of the CFF, and a part of the mainstream flows back to the upstream side through a gap between the tongue and the CFF. Therefore, we thought that the function of the tongue, which divide inflow and outflow, is not sufficient.

The influence of modifying the tongue shape was experimentally evaluated. The test results showed that the surging limit shifted to the low flow rate and high static pressure side, and the noise at the condition of the surging limit decreased. The surging phenomenon was suppressed by modifying the tongue shape at both ends of the CFF compared to the center area. This technique makes it possible to work the CFF in a more efficient OP.
An Optimization Study on Cavitation Flow in a Steam Trap Valve
Authors: Qiu Chang , Zhang Han , Yang Chen , Hou Cong-wei , Jin Zhi-jiang , Qian Jin-yuan
Published: November 2019

Steam trap valves are mainly used in thermal power systems to pour out condensate water and keep steam inside. While during the condensate water flowing through steam trap valves, the condensate water is easy to reaching cavitation, which may cause serious damage to the piping system. In order to reducing the cavitation occupation in steam trap valves, this paper mainly deals with an optimization study. With Computational Fluid Dynamics codes, numerical model of a typical steam trap valve is established with Mixture model. The inner pressure field, flow field and steam volume fraction are all achieved under both maximum flow rate working condition and regular working condition. Based on the cavitation results, the throttling stages of the steam trap valve are optimized. And the results show that cavitation range inside the steam trap valve is reduced.
Effects of Mass Eccentricity on the Motion of Spherical Particles in Shear Flows
Authors: Tanaka Mitsuru , Matsuura Akira , Tajiri Kyohei , Nishida Hidetoshi , Yamakawa Masashi
Published: November 2019

A particle-resolved simulation is performed on the motion of spherical particles with an eccentric internal mass distribution in laminar and turbulent vertical flows subjected to horizontal shear in order to examine the effects of mass eccentricity on the motion of particles in shear flows. A spherical shell/hollow particles with an inner spherical core is focused on as a typical example of mass eccentric particles. The Navier-Stokes equations and the Newton-Euler equations are solved for the fluid phase and the particles, respectively. An immersed boundary method is adopted to represent the shell particle. The Newton-Euler equations are solved using the body-fixed coordinate system and four quaternion parameters, considering the deviation of the mass center from the center of the spherical shell particle. Numerical results show that a particle tends to stop its rotation when the torque acting on the particle due to the gravity exceeds that due to the shear. It is found that the transverse migration of mass-eccentric particles becomes less vigorous in both laminar and turbulent flows since the effect of the Magnus force is also weakened for mass-eccentric particles. It is also found that the evolution of fluid kinetic energy is significantly affected by the mass-eccentricity of particles in laminar flows.
Investigations on Energy Shares and Flow Structures of the Mixing Flow Using 3D-POD Analyses
Authors: Kong Daekyeong , Cho Gyeongrae , Kim Myoung-Jin , Doh Deog Hee , Kang Sangmo , Suh Yong Kweon , Ninomiya Nao , Kang Sunghee
Published: November 2019

The objective of this report is investigate the influences of the mixing state to the productions of the vaterite crystal of CaCO3. In order to quantify the three-dimensional flow structures and their physical contribution to the mixing properties, a stereoscopic PIV (SPIV) has been adopted.

The SPIV systems consists of two high speed cameras and an optical encoder which is used for trigging the SPIV system to capture the instantaneous flow images. A continuous laser (550nm) has been used. For mixing, an agitator having four blades has been used. The mixing tank has been filled with water up to 85% level of the tank height. The agitator has been rotated with 200rpm, 250rpm and 300rpm, and the 3D flow structures have been captured by the constructed SPIV system.

Using measured instantaneous 3D vectors, POD (proper orthogonal decomposition) analyses has been adopted to investigate the energy distributions of the major vortical structures, and to evaluate the flow features regarding on the production of the vaterite crystal of CaCO3.
Analysis of Characteristics of Bubble on Electrode Surface of Forced Convective Electrolyte Using Image Processing
Authors: Lee Jaewon , Sohn Dong Kee , Ko Han Seo
Published: November 2019

‘Electrolysis’ is a technology about the transport of electrons caused by placing electrodes in an electrolyte using the difference of electric potential. It has been applied to various industrial fields, e.g., energy storage systems (ESS), fuel cells, and water treatment. Despite the outwardly simple phenomenon of this technology, it has been investigated because of the complex electro-physical process inside the electrolysis system, which can be designed in various ways. Two plate electrodes placed on a bulk of electrolyte is the most common electrolysis system. The electrolysis systems can be identified by the electrolyte flow, such as Forced convection configuration (FCC), Forced convection-induced circulation configuration (FCICC), and No net flow configuration (NNFC). The purpose of the study about the bubbles around the electrodes was to characterize the potential drop induced by the existence of the bubbles in the electric field. The dispersed bubbles, which have less electrical conductivity than does the bulk of the electrolyte, can reduce the efficiency of electrolysis. Therefore, in order to study the relationship between the electrical properties in the channel and the gas layer, the equation was derived with the void fraction and other electrical variables.
Fabrication and Testing of a Magnetophoretic Bioseparation Chip for Isolation and Detection of Circulating Tumor Cells From Peripheral Blood
Authors: Jackson Seth , Darabi Jeff , Schober Joseph
Published: November 2019

Significant research involving the isolation and detection of circulating tumor cells (CTCs) has become prevalent in the field of biomedicine. It plays a crucial role in the diagnosis and treatment of cancer and has made substantial strides in recent years. A major event in the timeline of cancer is metastasis, a set of occurrences where cells are shed from a cancerous site, then flow through the circulatory system and seed themselves throughout the body, forming secondary tumors. There are few observable symptoms in the early stages of metastasis and this fact severely limits clinical treatment. The fabrication and preliminary testing of a magnetophoretic bioseparation chip capable of isolating and detecting CTCs from peripheral blood, which can aid in early detection of metastases, is presented in this work. MCF7 breast cancer cells along with superparamagnetic microparticles, which are specifically coated with anti-EpCAM to bind to the cancer cells, are spiked into a blood sample. After the spiked blood sample is introduced into the biochip, a locally engineered magnetic field gradient captures the magnetically labeled cancer cells while the non-target cells are allowed to pass by. Once the target cells are isolated from the blood sample, flow cytometry is used to determine the recovery rate of the magnetophoretic device. The proposed device can operate at continuous flow rates magnitudes higher than other CTC isolation devices and is fabricated using much simpler methods which make it quite unique. These properties combined with greater than 80% recovery rates make the device quite favorable for economic point of care use in clinical applications.
A Finite Element Based Partitioned Coupling Method for the Simulation of Flow-Induced Fiber Motion
Authors: Zhang Diwei , Peng Xiaobo , Zhang Dongdong
Published: November 2019

A finite element based partitioned coupling method is presented for the simulation of flow-induced fiber motion in this paper. Quasi-static Stokes equation is used as the governing equation of the fluid domain. Mixed finite element is used to solve it. Fiber motion is modeled as a nonlinear geometric dynamic problem. Total-Lagrangian incremental finite element method is used to address the nonlinear geometry. Bathe method is applied to discretize the time domain. Then, two domains are coupled by a loosely partitioned coupling strategy. The derived method can be applied to the simulations of fiber motion in the low Reynolds number fluid, e.g. an injection molding process for manufacturing short fiber reinforced composite materials. In this paper, the effects of fiber shape, axis ratio of fiber, and boundary effect on the fiber’s motion are discussed. A phenomenon of repulsion is found in a simulation of the double-particle motion immersed in the double Couette flow.
An Evaluation of Open Source CFD for Study of Aerodynamics of Vehicle Platooning
Authors: Farid T. , Shakeel A. , Sajid M.
Published: November 2019

The ever-growing road congestion and safety hazards induced by conventional highways has inspired the development of automated highways which provides four key benefits: fuel economy, environmental protection, road safety and smooth traffic flow. Vehicle platooning is a vital component of automated highways which contributes directly to these four benefits with its sequence of closely spaced leader-follower vehicle configuration by taking advantage of the ‘slip-stream’ effect to minimize the aerodynamic drag. Exploratory studies into platooning parameters, vehicle spacing, speeds and number of vehicles, have proven to be prohibitive expensive both computationally and experimentally due to the complexity of tests and the large number of test cases. In recent years, OpenFOAM® an independently developed, supported and documented open-source toolbox has gained popularity by offering a lower cost alternative to leading commercial CFD products. This paper summarizes the results from a computational study of autonomous vehicle platoons and the capability of OpenFOAM® to substitute leading commercial CFD solutions currently used to support vehicle aerodynamic development. This study investigates the aerodynamic characteristics of a 4-SUV platoon at inter-vehicle distances ranging from 0.25 to 1 SUV length at a constant speed of 23 m/s. Trends of the predicted aerodynamic drag coefficients (Cd) are then compared against experimental data from published literature as well as the results obtained from a leading commercial CFD package.
A Numerical Study on Improvement of Coating Uniformity by Controlling the Pressure at the Exit of the Slot Die Nozzle
Authors: Oh Sang Hyun , Kim Sung Il , Park Ki Ho , Yu Byeong Hyeok
Published: November 2019

In this study, numerical analysis was carried out to investigate the effects of slot die nozzle exit rear pressure on coating uniformity improvement in coating nozzles which are widely used in industry. Coating uniformity in coatings of viscosity materials such as inks and surface coating solutions is closely related to the quality of the product. Especially, coating uniformity is an important performance indicator for slot die coatings, which are used primarily in the production of optical or chemical products such as displays, touch screens, solar panels, and batteries. In general, the average thickness of a thin film in a slot die coating is determined by the supply flow rate and the moving speed of the plate. However, due to various parameters, thickness irregularities and coating defects due to pores occur locally. Therefore, many studies have recently been performed to solve the local defect of the slot die coating. In order to improve the coating uniformity, this study applied the vacuum pressure condition to the slot die nozzle rear end and numerical study on the coating uniformity according to the vacuum pressure was carried out. The numerical analysis proceeded to 2-D, unsteady condition and the VOF method. A commercial numerical simulation software (STAR-CCM+ V.12.06) was used. It was simulated that the coating liquid was supplied onto the moving plate surface. The moving plate speed was fixed 0.01m/s. The nozzle geometry simulates a slot die nozzle. And the coating raw material supply flow rate was considered for two conditions (0.005, 0.006m/s). Two vacuum pressure conditions (−3, −300Pa) were applied to the rear end of the nozzle. The viscosity of the viscous material was fixed at 2 Pa.s. The analysis results were analyzed through the uniformity of the material supplied to the surface. As a result of analysis, uniformity of coating was lowered regardless of the velocity when the vacuum pressure condition was −3.0 Pa, and uniformity was lowered as the velocity increased. However, it was confirmed that uniformity of the coating was increased at all velocity condition when the vacuum pressure condition was −300 Pa. This is because as the flat plate moves, the reverse pressure is applied to the downstream of the coating solution, thereby improving the uniformity of the coating liquid flowing through the flat plate and preventing the inflow of air or the like. Through this study, it was confirmed that the coating uniformity can be improved by controlling the vacuum pressure at the rear end of the nozzle.
Ionic Wind Application to Vortex Ring Generator and its Transportation Efficiency
Authors: Fukunaga Kengo , Satake Masayoshi , Maeda Noboru , Shikata Kazushi , Ezaka Tomohisa
Published: November 2019

In this study, ionic wind generated in corona discharge is focused for producing an air flow without having mechanical actuators. First, the kinetic energy conversion efficiency to ionic wind from electric power is experimentally estimated to be 0.32%. Then, it is confirmed that intermittent blows of ionic wind enable to produce vortex rings without using mechanical system. We adopt novel sub-chamber structure to avoid the concentration of the substance in a vortex ring low, so that the substance concentration transported to the target distance of 200 mm increases by 9%. As an application, the efficiency for moisture transportation is evaluated through experimental measurements. As a result, it is shown that the substance (moisture) can be transported at an efficiency of about 85% to target distance of 200 mm under conditions where the influence of external turbulence is small.
Study of a Multistage Canned Motor Pump: Simulation, Optimization and Validation
Authors: Benigni Helmut , Mosshammer Markus , Jaberg Helmut
Published: November 2019

This paper describes the detailed analysis of a multistage canned motor pump with an additional radial suction impeller by means of CFD simulations to determine the main losses and to establish optimization potential of the hydraulic parts. In addition to the main flow channels of the impeller, the degree of detail of the analysis also includes the front and rear impeller side spaces, relief holes, gaps, return sections and all hydraulically wetted surfaces of the canned motor. The model presented was successively generated and already at a very early stage it was obvious that the model has to contain all details mentioned in order to provide valuable simulation results. For the impeller, the gaps and the pressure relief holes primarily structured meshes were used with a final model of the existing pump consisting of more than 35 million nodes. The behavior of the main components was analyzed in detail and additionally the CFD simulations — stationary and transient — with scale resolving turbulence models were validated by means of model tests. Furthermore, a comprehensive loss analysis of the existing pump was performed to verify the optimization potential. The subsequent optimization was realized semi-automated. A tight corset of requirements, e.g. identical head curve, suction behavior and dimensions, has been defined to guarantee retrofit capability of the pump analyzed in order to fully satisfy the demand for a constant delivery head curve and at the same time to provide for a relative increase of the optimum efficiency by 25% and in a wide range of applications by at least 20%. The optimized model was manufactured based on rapid prototyping and tested in the laboratory. The results show a satisfying correlation between the numerically predicted and the measured results on the test rig and prove the high quality of the numerical simulations run.