bluuebunny/crossref_metadata_2025 huggingface dataset:
A Mental Model of the Learner: Teaching the Basic Science of Educational Psychology to Future Teachers
Authors: Willingham Daniel T.
Published: October 2017

Although most teacher education programs include instruction in the basic science of psychology, practicing teachers report that this preparation has low utility. Researchers have considered what sort of information from psychology about children's thinking, emotion, and motivation would be useful for teachers' practice. Here, I take a different tack. I begin by considering three varieties of statements in basic science: empirical observations, theoretical statements, and epistemic assumptions. I suggest that the first of these can support classroom application, but the latter two cannot. I use that conclusion as a starting point for considering the instruction of prospective teachers in psychology.
Physiological augmentation of esophageal distension pressure and peristalsis during conditions of increased esophageal emptying resistance
Authors: Brink G. J. , Lei W. Y. , Omari T. I. , Singendonk M. M. J. , Hung J. S. , Liu T. T. , Yi C. H. , Chen C. L.
Published: October 2017

Background

Abdominal compression has been implemented as a provocative maneuver in high‐resolution impedance manometry (HRIM) to “challenge” normal esophageal physiology with the aim of revealing abnormal motor patterns which may explain symptoms. In this study, we measured the effects of abdominal compression on esophageal functioning utilizing novel pressure‐impedance parameters and attempted to identify differences between healthy controls and globus patients.

Methods

Twenty‐two healthy volunteers (aged 23‐32 years, 41% female) and 22 globus patients (aged 23‐72 years, 68% female) were evaluated with HRIM using a 3.2‐mm water perfused manometric and impedance catheter. All participants received 10 × 5 mL liquid swallows; healthy controls also received 10 × 5 mL liquid swallows with abdominal compression created using an inflatable cuff. All swallows were analyzed to assess esophageal pressure topography (EPT) and pressure‐flow metrics, indicative of distension pressure, flow timing and bolus clearance were derived.

Key Results

The effect of abdominal compression was shown as a greater contractile vigor of the distal esophagus by EPT and higher distension pressure based on pressure‐flow metrics. Age and body mass index also increased contractile vigor and distension pressure. Globus patients were similar to controls.

Conclusions and Interferences

Intrabolus pressure and contractile vigor are indicative of the physiological modulation of bolus transport mechanisms. Provocative testing by abdominal compression induces changes in these esophageal bolus dynamics.
The role of piezoelectric surgery and platelet‐rich fibrin in treatment of ORN and MRONJ: a clinical case series
Authors: Bilimoria R. , Young H. , Patel D. , Kwok J.
Published: October 2017

The potential of platelet‐rich fibrin, (or leucocyte platelet‐rich fibrin), has been increasingly promoted for a range of oral and maxillofacial procedures. These include bone regeneration around implants, survival of bone grafts in implant surgery, third molar extraction sockets and periodontal regeneration, and as an adjunct to adipocyte grafts in facial lipostructure. L‐PRF is an autologous blood product that contains a rich host of cytokines and growth factors and has been shown to accelerate and improve results in hard and soft tissue wound healing. This case series explores the role of L‐PRF in conjunction with piezoelectric debridement as a minimally invasive management technique in jaw necrosis. Osteoradionecrosis (ORN) and medicine‐related osteonecrosis of the jaw (MRONJ) are both debilitating complications of cancer treatments. With an ageing population, rise in incidence of oro‐pharyngeal cancers requiring chemo‐radiotherapy, and more prophylactic use of bisphosphonates, we are seeing an increase in ONJ. Rank L inhibitors and monoclonal antibodies are not just limited to cancer patients, but are also important in treatment of Paget's disease and osteoporosis. Management options range from pharmacological therapy to surgical treatment depending on the stage of the lesion, symptoms and patient's life expectancy. Recent evidence has shown minimally invasive surgical approach with flapless piezoelectric surgery could have a possible role in treatment of osteonecrosis of the jaw in stages 1 and 2 of the condition. As an adjunct to minimally invasive debridement, this case series looks at combining the use of piezodebridement with L‐PRF in stage 2 ONJ. (As in the AAOMS classification). We have a case series of (n = 10) patients, with (n = 12) ONJ lesions. They have been treated with piezoelectric debridement, placement of L‐PRF in the affected sites and primary closure where possible. In accordance with the most recent AAOMS classification, only cases with stage 2 were included; hence, where the defect was symptomatic, infected, conservative pharmacological therapy had failed, and size of the defect was appropriate for local resection only. Larger defects were excluded, that would otherwise require surgical debridement, major resection or jaw reconstruction. To assess the effect of piezodebridement and L‐PRF on mucosal coverage and soft tissue healing in ORN and MRONJ after extraction, trauma or spontaneous necrosis. Patients were followed up clinically and radiographically until total mucosal coverage of the necrotic bone was achieved. Of the 12 sites, 8 showed complete mucosal coverage within 1 year, 3 areas showed persistent exposed bone after 1 year, and 1 patient did not return for follow up.
Short‐term efficacy and nontarget effects of aerial glyphosate applications for controlling Lonicera maackii (Amur honeysuckle) in oak‐hickory forests of Eastern Missouri, U.S.A.
Authors: Leahy Michael J. , Vining Ivan W. , Villwock Jason L. , Wesselschmidt Raenhard O. , Schuhmann Andrea N. , Vogel John A. , Shieh David Y. , Maginel Calvin J.
Published: October 2017

Lonicera maackii (Amur honeysuckle) is a non‐native species that has invaded forest stands throughout the eastern United States. This research examined using aerially applied glyphosate in autumn 2013 to control L. maackii in oak‐hickory forest stands in Missouri, U.S.A. We targeted the spraying time period when L. maackii was still green and most native plants were dormant. Across treatment units, the mean difference in L. maackii stem density significantly declined (p = 0.004) by 5.4 stems per plot from spring 2013 to summer 2014 when compared to control units which increased by 1.8 stems per plot. Treated units with a high initial infestation level of L. maackii (>50% cover) had a significant (p = 0.004) decline in the mean difference in L. maackii cover of −50.0% per plot between spring 2013 and summer 2014 compared to an average increase of 9.2% in the controls. Similar results were found for treated units with a low initial infestation level of L. maackii (10–50% cover). Mortality of native overstory and understory trees post‐treatment was negligible. In the ground layer of forest stands with a low initial L. maackii infestation level, native non‐spray‐sensitive forb cover per plot significantly increased (p = 0.023) relative to controls between summer 2013 and summer 2014 while native spray‐sensitive species cover significantly decreased (p = 0.021) during the same period. These results suggest that an aerial application of glyphosate can provide an L. maackii control option, but with trade‐offs in compositional shifts in the native ground‐layer vegetation.
Three new HLA class I alleles with synonymous mutations: HLA‐A*03:01:62, ‐C*07:02:82 and ‐C*12:03:42
Authors: Moya‐Quiles M. R. , Balas A. , Muro M. , García‐Alonso A. M. , Vicario J. L.
Published: October 2017

Three new HLA class I alleles with synonymous mutations were identified.
The novel allele, HLA‐A*24:383, was identified in a Chinese individual by sequence‐based typing
Authors: Hu B. , Yang Z.‐X. , Pan H.‐P. , Pang S.‐T.
Published: October 2017

HLA‐A*24:383 differs HLA‐A*24:02:01:01 by one nucleotide substitution from C to G in exon 4, position 755.
Factorization of Force and Timing in Sensorimotor Performance: Long‐Range Correlation Properties of Two Different Task Goals
Authors: Balasubramaniam Ramesh , Hove Michael J. , Médé Butovens
Published: October 2017

Long‐range correlations are often manifested in the form of 1/fβ noise in a series of repeated measurements of the same neural or behavioral variable. Recent work has demonstrated that the magnitude and nature of these long‐range correlations reliably capture individual differences and variation in task performance. In sensorimotor timing experiments, task characteristics such as tapping or circle drawing affect these long‐range correlations during the production of isochronous time intervals. Such correlations are highly reproducible across multiple trials for the same task but do not correlate between tasks. In the present experiment, we investigate whether two behavioral variables that are simultaneously controlled by the same participant in a given experimental condition can show such differentially organized fluctuations. In order to answer this question, 13 participants were asked to produce repetitive movements with their right index finger at a specified time interval (500 ms) and a specified force (8N) in the absence of an auditory metronome and visual feedback of force levels following a synchronization‐continuation paradigm. Although participants showed high levels of consistency in the long‐range correlations for each task component separately over multiple trials/observations, the long‐range fluctuations for force and timing were found to show no correlations with each other for each participant. Cross recurrence quantification analyses (CRQA) revealed that there was limited shared structure between the timing and force time series data. Taken together, these results suggest that complex systems can organize multiple processes in a relatively independent manner while maintaining a high degree of reliability within one task parameter.
The application of solar distillation technique as a mean for olive mill wastewater management
Authors: Jaradat A. Q. , Gharaibeh S. , Abu Irjei Mustafa
Published: October 2017

The present study was conducted on a pilot scale level using a solar still unit to separate olive mill wastewater (OMW) into condensate and solid residue. The prevailing conditions inside the solar still, rates of distillation and a number of quality parameters for condensate [pH, electrical conductivity (EC), turbidity, chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN) and total‐phenols] were evaluated to assess the system performance. The solid residue was evaluated as well for its utility as a potential biofuel. The condensate is acidic (pH 3.8), colourless, transparent and free of suspended solids. The turbidity and EC were reduced in the condensate by 100 and 99%, respectively, while the loads of COD, TOC, TN and T‐phenols were reduced by 90, 98, 99.9 and 99.96%, respectively. Almost 0.04% of initial total phenols found in OMW were recovered in the condensate. High calorific value (23.5 kJ/g) and combustible portion (84%) of solid residue suggests its applicability as a potential biofuel
Model calibration and feed‐forward control of the wastewater treatment plant – case study for CLUJ‐Napoca WWTP
Authors: Nair Abhilash , Cristea Vasile‐Mircea , Agachi Paul Şerban , Brehar Marius
Published: October 2017

Although the activated sludge models for waste water treatment plants (WWTPs) offer comprehensive description of their involved biochemical and physical processes, it is a challenging task to calibrate the model for the operational plant. The article first presents a systematic calibrating procedure applied to the Activated Sludge Model No.1 (ASM 1), showing its potential to be extended to other WWTPs. It particularly addresses cases when comprehensive knowledge on the WWTP influent composition does not exist. An optimisation‐based approach is used for the WWTP model calibration and for finding the partially unknown influent composition. Dynamic model validation shows good match between model predicted values and WWTP measured data. Second, a new feed‐forward control strategy is designed for the WWTP and compared with the conventional nitrate‐nitrite nitrogen and dissolved oxygen control. The evaluation based on the effluent quality index, pumping and aeration energy and the number of effluent violations assessment tools, demonstrates incentives for the proposed control approach.
PDA Measurements in Spray Generated by Twin-Jet-Nozzles
Authors: von Deschwanden Inez , Benra Friedrich-Karl , Dohmen Hans Josef , Brillert Dieter
Published: October 2017

Generating fine widely dispersed sprays is the current focus of research. For this purpose, different types of nozzles are available. In the present paper, the continuous spray formation generated by the collision of two individual water jets is examined. All measurements are conducted in steady-state at ambient temperature and pressure. A non-invasive Phase-Doppler-Anemometry (PDA) laser measurement system enables the spray characteristics to be determined, the droplet distribution and the droplet velocity. Twin-jet-nozzles generate a fine but dense spray. The PDA measurement technique is an optical measurement application. The intensity of the light scattered by the droplets is proportional to the droplets squared diameter. Especially, in dense sprays, a high intensity of light signals is required for high quality data acquisition. Furthermore, the outcome of PDA measurement depends mainly on three aspects: One aspect is the influence of the laser power on the signal intensity. The second important parameter is the voltage of the Photo-Multiplier-Tubes. The third aspect is the orientation of transmitter and receiver of the measurement equipment relative to the spray. In this paper, the precision of PDA measurements in dense sprays influenced by the PMT voltage is analyzed and discussed.
Resistant Energy Analysis of Dropwise Condensation on Superhydrophobic Surfaces With Hierarchical Roughness
Authors: Cheng Jiangtao
Published: October 2017

Recently there have appeared multiscale lotus-leaf-like superhydrophobic surfaces that can enhance dropwise condensation in well-tailored supersaturation conditions. However, designs of most biomimetic surfaces were not driven by the understanding of underlying physical mechanisms. We report energy-based analysis of growth dynamics of condensates from surface cavities. As observed in condensation experiments, these textured surfaces with two tier roughness are superior to flat or solely nanotextured surfaces in spatial control of condensate droplets. To understand the role of condensate state transition in enhancing condensation heat transfer, we considered adhesion energy, viscous dissipation and contact line dissipation as the main portion of resistant energy that needs to be overcome by the condensates formed in surface cavities. By minimizing the energy barrier associated with the self-pulling process, we optimized first tier roughness on the hierarchically textured surfaces allowing condensates to grow preferentially in the out-of-plane direction. The nano-roughness of the second tier plays an important role in abating the adhesion energy in the cavities and contact line pinning. From the perspective of molecular kinetic theory, the dual scale engineered surface is beneficial to remarkably mitigating contact line dissipation. This study indicates that scaling down surface roughness to submicron scale can facilitate self-propelled condensate removal.
Gas-Induced Motion of an Object in a Liquid-Filled Housing During Vibration: Part I — Analysis
Authors: Torczynski John R. , O’Hern Timothy J. , Clausen Jonathan R. , Koehler Timothy P.
Published: October 2017

Models and simulations are employed to analyze the motion of a spring-supported piston in a vibrated liquid-filled cylinder. The piston motion is damped by forcing liquid through a narrow gap between a hole through the piston and a post fixed to the housing. As the piston moves, the length of this gap changes, so the piston damping coefficient depends on the piston position. This produces a nonlinear damper, even for highly viscous flow.

When gas is absent, the vibration response is overdamped. However, adding a little gas changes the response of this spring-mass-damper system to vibration. During vibration, Bjerknes forces cause some of the gas to migrate below the piston. The resulting pneumatic spring enables the liquid to move with the piston so as to force very little liquid through the gap. Thus, this “Couette mode” has low damping and a strong resonance near the frequency given by the pneumatic spring constant and the total mass of the piston and the liquid. Near this frequency, the amplitude of the piston motion is large, so the nonlinear damper produces a large net force on the piston.

To analyze the effect of this nonlinear damper in detail, a surrogate system is developed by modifying the original system in two ways. First, the gas regions are replaced by upper and lower bellows with similar compressibility to give a well-defined “pneumatic” spring. Second, the upper stop against which the piston is pushed by its lower supporting spring is replaced with an upper spring, thereby removing the nonlinearity from the stop.

An ordinary-differential-equation (ODE) drift model based on quasi-steady Stokes flow is used to produce a regime map of the vibration amplitudes and frequencies for which the piston is up or down for conditions of experimental interest. These results agree fairly well with Arbitrary Lagrangian Eulerian (ALE) simulations of the incompressible Navier-Stokes (NS) equations for the liquid and Newton’s 2nd Law for the piston and bellows.

A quantitative understanding of this nonlinear behavior may enable the development of novel tunable dampers for sensing vibrations of specified amplitudes and frequencies.
Inner Flow Field PIV Measurement and Study on Turbulence Generator of Medium Consistency Pump
Authors: Daoxing Ye , Xide Lai
Published: October 2017

In order to study the flow characteristic in turbulence generator of medium consistency pump, a new particle image velocimetry (PIV) test rig was established. 2D-plane flow field was acquired fast and effective by adjusting the angle and position of mirror. For investigate the effect of speed on flow field, velocity and turbulent kinetic energy were measured at speed 80r/min, 130r/min and 200r/min. Dimensionless method was adopted to analyze flow field by quantitative approach. The results showed that on vertical flow plane axial velocities decrease with radius increasing in the region of turbulence generator blade, and axial velocity direction was changed and increase with radius increasing outside the region of turbulence generator blade. Internal flow direction of turbulence generator is at opposite direction with outside flow. Fluid flows from inlet to outlet of turbulence generator blade and then go back to inlet, which forms a circle. On horizontal flow plane, circumferential velocity increase with radius increasing firstly, and then the maximum appears at Outer diameter of turbulence generator, and last it decreases gradually. Turbulent kinetic energy increases with rotational speed increasing at inner of turbulence generator flow field, and high turbulent kinetic energy mainly concentrates near the blade inlet and external diameter of turbulence generator. Therefore, in order to achieve better turbulence effect, high turbulent kinetic energy can be obtained by changing the shape of blade inlet structure, increasing the blade outside diameter and improving rotational speed.
Using Direct Numerical Simulations for Investigating Physics of Turbulence in Porous Media
Authors: Jin Y. , Kuznetsov A. V.
Published: October 2017

One of the most controversial topics in the field of convection in porous media is the issue of macroscopic turbulence. It remains unclear whether it can occur in porous media. It is difficult to carry out velocity measurements within porous media, as they are typically optically opaque. At the same time, it is now possible to conduct a definitive direct numerical simulation (DNS) study of this phenomenon. We examine the processes that take place in porous media at large Reynolds numbers, attempting to accurately describe them and analyze whether they can be labeled as true turbulence. In contrast to existing work on turbulence in porous media, which relies on certain turbulence models, DNS allows one to understand the phenomenon in all its complexity by directly resolving all the scales of motion.

Our results suggest that the size of the pores determines the maximum size of the turbulent eddies. If the size of turbulent eddies cannot exceed the size of the pores, then turbulent phenomena in porous media differ from turbulence in clear fluids. Indeed, this size limitation must have an impact on the energy cascade, for in clear fluids the turbulent kinetic energy is predominantly contained within large eddies.
CFD Simulation of Three Phase Gas-Liquid-Solid Flow in Horizontal Pipes
Authors: Sultan Rasel A. , Rahman Mohammad Aziz , Zendehboudi Sohrab , Kelessidis Vassilios C.
Published: October 2017

The objective of this work is to analyze fluid flow in horizontal pipes with three phase gas-liquid-solid Newtonian fluid by our developed CFD simulation model and validate the simulation with experimental works. Air as gas, water as liquid and silica sand as solid particle is used for this work. ANSYS fluent version 16.2 is used to do the simulation. Eulerian model with Reynolds Stress Model (RSM) turbulence closure is adopted to analyze multiphase fluid flow. Length of pipe is 2.9 m and diameter is 0.0416 m, which are selected from experimental works to validate the simulation and after a good agreement with experimental data, sensitivity analysis is conducted to observe the three phase fluid flow characteristics through horizontal flow. Pressure gradient (pressure drop per unit length) is used as primary parameter to analyze. Effect of in situ concentration of solid in slurry, diameter of pipeline, roughness of wall material and viscosity of water in slurry are analyzed throughout this paper. This article provides validity of our proposed model. After that we tried to perform some parametric studies, changing variables of three phase fluid flow through horizontal pipeline with ours validated model. The main approach here is to demonstrate our CFD model in different ways to researchers and industries related to multiphase pipeline flow fields and make it acceptable to them. Also, Fluid Structure Interaction (FSI) is introduced at the end of this study to explain the goal of this project.
Coarse Grained Simulation of Shock-Driven Turbulent Mixing
Authors: Grinstein Fernando , Rauenzahn Rick , Saenz Juan , Francois Marianne
Published: October 2017

We focus on the simulation of shock-driven material mixing powered by flow instabilities dependent on initial conditions (IC) at the material interfaces. Beyond complex multi-scale resolution issues of shocks and variable density turbulence, we must address the equally difficult problem of predicting flow transition promoted by energy deposited at the interfacial layers during the shock-interface interactions. Transition involves IC-dependent, large-scale coherent-structure dynamics capturable by a large eddy simulation (LES) strategy, but not by unsteady Reynolds-Averaged Navier-Stokes (URANS) approaches based on equilibrium developed turbulence assumptions and single-point-closure modeling. On the engineering end of computations, reduced-dimensionality (1D/2D) versions of such URANS tend to be preferred for faster turnaround in full-scale configurations. With suitable initialization around each transition, URANS can be used to simulate the subsequent near-equilibrium weakly turbulent flow. We demonstrate 3D state-of-the-art URANS performance around one such (reshock) transition — in the context of a sequential LES/URANS strategy.
Computational Model Development and Failure Mode Investigation for a Magnetically-Driven Bearingless Micro-Pump
Authors: Goodwin Gabriel B. , Maxwell Jesse R. , Hoang Triem T.
Published: October 2017

As the electronics systems aboard air and spacecraft grow in scale and complexity, so too does the heat generated by those systems. A high-heat flux, compact, maintenance-free cooling system is required to meet the increased demand for heat removal. Loop heat pipes are robust and effective thermal management systems that are long-life and maintenance-free, making them ideal for use in unmanned spacecraft. Integrating a mechanical pump into a loop heat pipe system can drastically improve the system’s heat removal capacity through increased mass flowrate. Like loop heat pipes, magnetically-driven bearingless pumps are also maintenance-free, which is a necessity in the space environment. This work details the modeling of a low-flowrate, magnetically-driven bearingless centrifugal pump and a computational fluid dynamics study of the pump’s operation and performance under a range of conditions that are typical to the demands of a satellite thermal management system. The purpose of this computational study is to investigate the failure mechanism of a bench-test unit that was unable to generate a pressure head with its intended working fluid of ammonia. Model development, validation, and pump performance with multiple working fluids are discussed. The cause of the pump’s failure is investigated.
Validation of Test Methods for Air Leak Rate Verification of Spaceflight Hardware
Authors: Oravec Heather A. , Daniels Christopher C. , Mather Janice L.
Published: October 2017

As deep space exploration continues to be the goal of NASA’s human spaceflight program, verification of the performance of spaceflight hardware becomes increasingly critical. Suitable test methods for verifying the leak rate of sealing systems are identified in program qualification testing requirements. One acceptable method for verifying the air leak rate of gas pressure seals is the tracer gas leak detector method. In this method, a tracer gas (commonly helium) leaks past the test seal and is transported to the leak detector where the leak rate is quantified. To predict the air leak rate, a conversion factor of helium-to-air is applied depending on the magnitude of the helium flow rate. The conversion factor is based on either the molecular mass ratio or the ratio of the dynamic viscosities. The current work was aimed at validating this approach for permeation-level leak rates using a series of tests with a silicone elastomer O-ring. An established pressure decay method with constant differential pressure was used to evaluate both the air and helium leak rates of the O-ring under similar temperature and pressure conditions. The results from the pressure decay tests showed, for the elastomer O-ring, that neither the molecular flow nor the viscous flow helium-to-air conversion factors were applicable. Leak rate tests were also performed using nitrogen and argon as the test gas. Molecular mass and viscosity based helium-to-test gas conversion factors were applied, but did not correctly predict the measured leak rates of either gas. To further this study, the effect of pressure boundary conditions was investigated. Often, pressure decay leak rate tests are performed at a differential pressure of 101.3 kPa with atmospheric pressure on the downstream side of the test seal. In space applications, the differential pressure is similar, but with vacuum as the downstream pressure. The same O-ring was tested at four unique differential pressures ranging from 34.5 to 137.9 kPa. Up to six combinations of upstream and downstream pressures for each differential pressure were compared. For a given differential pressure, the various combinations of upstream and downstream dry air pressures did not significantly affect the leak rate. As expected, the leak rate of the O-ring increased with increasing differential pressure. The results suggested that the current leak test pressure conditions, used to verify spacecraft sealing systems with elastomer seals, produce accurate values even though the boundary conditions do not model the space application.
Fuel Production From Plastic Wastes Pyrolysis
Authors: Berrich-Betouche Emna , Dhahak Asma , Touati Abdelaziz , Aloui Fethi
Published: October 2017

Energetic valorization of thermoplastic wastes (High-density polyethylene (PE) and Polypropylene (PP)) to produce fuel using pyrolysis process is presented in this paper. HDPE and PP pyrolysis experiments were carried out in a lab-scale batch reactor under an inert atmosphere. Nitrogen gas was used as carrier before and during the experiments. The temperature was varied from 293 K to approximately 773 K. The viscosities of HDPE, PP and the mixture 50% HDPE & 50 % PP pyrolysis liquids are respectively equal to 1.08 cP, 0.67 cP and 0.8 cP. Its densities are respectively equals to 0.735, 0.751 and 0.759 (at 20 °C–30 °C). The high calorific value (the heating Value) is respectively equals to 45.235 ± 0.641 MJ/kg, 46.151 ± 1.33 MJ/kg and 45.393 ± 0.87 MJ/kg. The liquids obtained have approximately the same Kerosene (Coal Oil) high calorific value (46 MJ/kg). The flash points are respectively equal to 32 °C, 31 °C and lesser than 25 °C for the mixture. They are lesser than coal oil and Diesel values which are equal to 38 °C for Kerosene and between 38 °C and 58 °C for Diesel.

The mixture of two polymers decreases the viscosity values comparing to coal oil (1.7 cP) and Diesel (3.35 cP).
Preconditioning for the All-Speed Compressible Navier-Stokes Equations With Laser-Induced Phase Change
Authors: Weston Brian , Delplanque Jean-Pierre , Nourgaliev Robert
Published: October 2017

We present a new block-based preconditioner for simulating all-speed compressible flow with phase change. The conservation equations are discretized with a reconstructed Discontinuous Galerkin method and integrated in time with fully implicit time discretization schemes. The resulting set of non-linear equations is converged using a robust Newton-Krylov framework. Due to the stiffness of the underlying physics associated with stiff acoustic waves and viscous material strength effects, we solve for the primitive-variables (pressure, velocity, and temperature). To enable convergence of the highly ill-conditioned linearized systems, we develop a physics-based preconditioner, utilizing approximate block factorization techniques to reduce the fully-coupled 3 × 3 system to a pair of reduced 2 × 2 systems. We demonstrate that our preconditioned Newton-Krylov framework converges on very stiff multi-physics problems with excellent algorithmic and parallel scalability. Results are shown for the classic lid-driven cavity flow problem as well as for 3D laser-induced phase change.
Lubricant Inertia in Water Lubricated Bearings
Authors: Deng Xin , Watson Cori , Weaver Brian , Wood Houston , Fittro Roger
Published: October 2017

Oil-lubricated bearings are widely used in high speed rotating machines such as those used in the aerospace and automotive industries. However, with some applications including underwater machinery and environmentally friendly applications, water lubricated bearings have become increasingly used. Due to the different fluid properties between oil and water — namely viscosity — the use of water increases the Reynolds numbers drastically and, therefore, makes water-lubricated bearings prone to turbulence and fluid inertia effects. In other words, the linear approximation of the fluid film reaction forces due to the stiffness and damping parameters — as suggested in the traditional Reynolds equation — is not adequate and should be amended to include lubricant added mass. This is because water-lubricated bearings exhibit large lubricant inertia forces on the order of viscous forces. Additionally, stiffness and damping coefficients should be calculated with the turbulence effects included. The aim of this study was to investigate the methodology of modifying the traditional Reynolds equation to include lubricant inertia effects. This paper reviews the current status of research in the lubricant inertia of bearings and explores the development of methodologies to modify the Reynolds equation to include lubricant inertia in bearings.

The Reynolds equation is a partial differential equation governing the pressure distribution of thin viscous fluid films in lubrication theory. The thin film hypothesis is used to directly relate the bearing film thickness to the lubricant film pressure. Adding lubricant inertia to the Reynolds equation is vital to improving the accuracy of the bearing model and more specifically its film pressure which is essential to predicting load carrying capabilities. The film pressure relates the gradient of the velocity tensor through the Reynolds equation, and resulting shear stresses then allow the turbulent momentum equations to be written in terms of an eddy-viscosity value. An extended Reynolds equation should be developed which takes into account turbulence and both convective and temporal inertia. The most complete form of the temporal inertia effect model should be developed and applied to the turbulent regime, consisting of both primary and secondary temporal inertia terms. The convective inertia model follows Constantinescu’s approach. This analysis develops a lubricant inertia model applicable to water-lubricated bearings. The results of this study could aid in improving future designs and models of water-lubricated bearings.
Vortical Flow Structure of Hub-Corner Separation in a Stator Cascade of a Multi-Stage Transonic Axial Compressor
Authors: Saito Seishiro , Furukawa Masato , Yamada Kazutoyo , Tamura Yuki , Matsuoka Akinori , Niwa Naoyuki
Published: October 2017

In this study, the hub-corner separation in a multi-stage transonic axial compressor has been investigated using a large-scale detached eddy simulation (DES) with about 4.5 hundred million computational cells. The complicated flow field near the hub wall in a stator with partial tip clearances was analyzed by data mining techniques extracting important flow phenomena from the DES results. The data mining techniques applied in the present study include vortex identification based on the critical point theory and topological data analysis of the limiting streamline pattern visualized by the line integral convolution (LIC) method.

It is found from the time-averaged flow field in the first stator that the hub-corner separation vortex formed near the solid part of the stator tip interacts with the leakage flow and secondary flow on the hub wall, resulting in a complicated vortical flow field. Near the leading edge of the stator, the leakage flow from the front partial clearance generates the tip leakage vortex, which produces loss from the leading edge to 10 percent chord position. At the mid-chord, the hub-corner separation vortex suffers a breakdown, resulting in the widespread huge loss production. It is shown from limiting streamlines on the suction surface of the stator that a reverse flow region expands radially from the solid part of the stator tip toward the downstream. From 50 percent chord position to the trailing edge of the stator, the leakage flow through the rear partial clearance interacts with the secondary flow on the hub wall. The leakage vortex generated along the rear partial clearance becomes a major loss factor there.
Lattice Boltzmann Method Simulation of Turbulent Indoor Airflow Using Hybrid LES/RANS Model
Authors: Sajjadi H. , Salmanzadeh M. , Ahmadi G. , Jafari S.
Published: October 2017

In this study the hybrid RANS/LES turbulence model within the framework of the Lattice Boltzmann method (LBM) was used to study turbulent indoor airflows. In this approach the near wall region was simulated by the RANS model, while the bulk of the domain was analyzed using the LES model with the LBM approach. In the near wall layer where RANS was used, the k-ε turbulence model was employed. For the k-ε turbulence model in conjunction with the LBM two population balance equations for k and ε were used.

The present simulation results for the airflow showed good agreement with the experimental data and the earlier numerical results for the hybrid RANS/LES. The results showed that the hybrid model properly predicted the large scale turbulence fluctuation velocities in the bulk of the flow region. In addition, the computational time for the hybrid model is less than that of the LES method.
Particles Transport in Railway Braking Systems: An Experimental and Numerical Investigation
Authors: Octau Charlene , Lippert Marc , Graziani Anthony , Watremez Michel , Keirsbulck Laurent , Dubar Laurent , Dbouk Talib
Published: October 2017

There has been a growing public health issue concerning the regulation of indoor air quality (IAQ) and the human exposure to particulate matter (PM). Today, this exposure is a major worldwide concern because ambient PM concentrations in many cities exceeded the limits set by the European air quality directive. Underground airborne particles are mainly generated by the mechanical abrasion of rail tracks, wheels and brake pads produced by urban railways transportation. For that reason, understanding the transport mechanism of particles with various size distribution is essential and crucial for understanding and accurately predicting the behavior of the main high particle concentration areas. In this framework, a simple case of particles emission inside a viscous flow in a channel has been investigated both experimentally and numerically. The suspended particles used experimentally are molybdenum solid particles with a broad size distribution (in diameter) from 1 to 80 μm (size similar to cases such as in braking systems). The experimental tests are conducted for a flow in a channel at a horizontal steady inflow velocity of uf = 0.15m/s. The solid particles are injected transversely to the horizontal bottom wall with an injection steady velocity of ui = 0.95m/s. Measurements and analysis are carried out using shadowscopy technique to determine the particles concentration fields. Finally, experimental results are compared to numerical ones predicted by a continuum computational fluid dynamics (CFD) approach using the SBM (Suspension Balance Model) implemented in “OPENFOAM” (via the Finite Volume Method).
Numerical Study on Ventilated Cavitation Influenced by Injection of Drag-Reducing Solution
Authors: Wang Lu , Liu Ping-An , Zheng Zhi-Ying , Wang Yue , Cai Wei-Hua , Li Feng-Chen
Published: October 2017

The influence of injection of drag-reducing solution on ventilated partial cavitation and supercavitation for an axisymmetric underwater vehicle is analyzed by numerical simulation. Turbulence, cavitation and multiphase models are SST k-ω, Schnerr-Sauer and Mixture models, respectively. The Cross viscosity equation is adopted to represent the fluid property of aqueous solution of drag-reducing additives. First of all, for non-cavitating conditions, the pressure distribution is obtained to determine the positions of injecting drag-reducing solution and ventilation. Then natural cavitation at different cavitation numbers is investigated for acquiring inception cavitation number. Finally, numerical simulations are conducted on the ventilated cavitating flows with and without the injection of drag-reducing solution at the cavitation number slightly smaller than the inception cavitation number (partial cavitation) and much smaller than the inception cavitation number (supercavitation). It is shown that for partial cavitation, the shape of cavity with the injection of drag-reducing solution is larger and the resistance of underwater vehicle decreases in comparison with the case without the injection of drag-reducing solution. However, for supercavitation, just viscous drag force obviously decreases, while cavity shape does not change.
Numerical Study on Pressure Difference of Valve Core in Vertical Pilot-Control Globe Valve
Authors: Gao Zhi-xin , Chen Fu-qiang , Qian Jin-yuan , Jin Zhi-jiang
Published: October 2017

Vertical pilot-control globe valve (VPCGV) is a novel globe valve that costs little driving energy and responds quickly. In VPCGV, the opening and closing forces are related to the pressure difference before and after the valve core. In this paper, parameters that have influences on pressure difference such as orifice diameter, valve core displacement, and inlet velocity are thoroughly investigated by computational fluid dynamics (CFD) method. It is found that pressure difference increases with the raising of inlet velocity and the diminishing of valve core displacement, and middle-sized orifice diameter is the best in VPCGV. Furthermore, the correlation between pressure difference and inlet velocity is obtained, which can be beneficial for the selection of VPCGV under certain conditions.
Development of a Bead-Based Optoelectrokinetic Immunosensing Technique for Detection of Low-Abundance Analytes
Authors: Chuang Han-Sheng , Lin Hsiao-Neng , Ku Hu-Yao
Published: October 2017

Bead-based immunosensing has been growing as a promising technology in the point-of-care diagnostics because of great flexibility. For dilute samples, functionalized particles can be used to collect dispersed analytes and act as carriers for particle manipulation. To carry out rapid and selective diagnosis, a bead-based optoelectrokinetic immunosensing technique was developed herein to detect biomarkers, lipocalin 1 (LCN1) and TNF-α, for diabetic retinopathy (DR). The measurement was made in a sample droplet sandwiched between two parallel electrodes. With an electric field and a focused laser beam simultaneously applying on the microchip, the immunocomplexes in the droplet were further concentrated within the region of irradiation to enhance the fluorescent signal. The optoelectrokinetic platform, termed rapid electrokinetic patterning (REP), is excellent in dynamic and programmable particle manipulation. Therefore, the detection could be complete in roughly 10 s. With an appropriate frequency modulation, the two DR biomarkers were detected at a time. The limit of detection (LOD) of the REP-enabled measurement reached as low as 100 pg/mL. The combined use of bead-based immunoassays and the optoelectrokinetic platform therefore provides an insightful measure to the early diagnosis of diseases.
Verification and Validation of the Caelus Library: Incompressible Turbulence Models
Authors: Stephens Darrin W. , Jemcov Aleksandar , Sideroff Chris
Published: October 2017

In this work verification and validation of Reynolds Averaged Navier-Stokes (RANS) turbulence models for incompressible flows was performed on the numerical library, Caelus [1]. Caelus is free and open source licensed under the GNU Public License (GPL). The focus of this study is on the verification and validation of the k-ω SST [2, 3], Spalart-Allmaras [4], and realizable k-ε models [5]. The cases used in this work include the zero pressure gradient flat plate, two-dimensional bump in a channel flow, NACA 0012 airfoil, and backward facing step. All cases except the backward facing step include mesh dependency studies. A comprehensive description of the test cases and computed results are provided. The results were, in general, found to be in excellent agreement with external data suggesting that the turbulence model implementations in Caelus are correct. A companion study on verification and validation of a predictor corrector steady-state solver algorithm [6] had similar goals and results as this work.
CFD Analysis of the Effect of Rolling Motion on the Characteristic of Labyrinth Seal
Authors: Huang Ning , Li Zhenlin , Li Shiyao , Zhang Ning , Dong Zhihui
Published: October 2017

With the development of offshore oil and gas industry, LNG turbo expanders are widely used in Floating Liquid Natural Gas equipment (FLNG) for natural gas transportation. The performance characteristic of the turbo expander is significant affected by the rolling motion caused by the ocean conditions. As an important part of expander, the labyrinth seal is directly related to the safety of the expander, so it is necessary to study the performance characteristic of labyrinth seal under rolling motion.

In this paper, CFD is used to simulate the internal flow field of labyrinth seals under different rolling periods and sloshing amplitudes conditions. The distribution of the pressure drop is obtained, and the influence of rolling motion on different labyrinth seal radial clearances and cavity depths are discussed.

The results indicate that variation periods of the pressure drop are consistent with the rolling periods, and the larger the rolling amplitude is, the larger pressure drop fluctuation can be observed. Additionally, the fluctuation characteristic is significantly affected by gap widths and cavity depths.
Flow Characteristics of Axial-Flow Fans With an Upstream/Downstream Blockage Disk
Authors: Ochiai Keiichi , Nakamura Shinsaku , Sato Kotaro , Kang Donghyuk , Yokota Kazuhiko
Published: October 2017

Axial-flow fans have been used in various applications such as thermal control and ventilation. Fans are often used in narrow spaces around obstacles such as electric parts, areas near clogged of fan filters, and walls. These obstacles lead to decreased performance and increased noise and vibration in electric devices. This study attempts to experimentally clarify the influences of upstream/downstream-mounted blockage disks on the flow characteristics of an axial-flow fan. The important results are summarized as follows: (1) For the same relative distance, the pressure performance and efficiency curves of the fan owing to the upstream-mounted blockage disk completely differ from those owing to the downstream-mounted blockage disk. (2) For a small relative distance, the pressure coefficient owing to the upstream and downstream-mounted blockage disks decreases and increases, respectively. (3) The efficiency of the fan owing to the upstream-mounted blockage disk decreases. However, the efficiency owing to the downstream-mounted blockage disk increases for specific conditions.
A VoF-Based Consistent Mass-Momentum Transport for Two-Phase Flow Simulations
Authors: Orazzo Annagrazia , Lagrange Isabelle , Estivalézes Jean-Luc , Zuzio Davide
Published: October 2017

The most part of two-phase flows relevant to industrial applications is characterized by high density ratios that make numerical simulations of such kind of flows still challenging in particular when the interface assumes complex shape and is distorded by high shear. In this paper a new strategy, to overcome the numerical instabilities induced by the large densities/shears at the interface, is described for staggered cartesian grids. It consists in a consistent mass-momentum advection algorithm where mass and momentum transport equations are solved in the same control volumes. The mass fluxes are evaluated through the Volume-of-Fluid color function and directly used to calculate momentum convective term. Two and three-dimensional high-density test cases (the density ratio goes from 103 to 109) are presented. The new algorithm shows signifcantly improvements compared to standard advection methods therefore suggesting the applicability to the complete atomization process simulations.