bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective Body Shape for Reducing Yawing Moment in Cross Wind
Authors: Matsui Akitoshi , Hishida Koichi
Published: June 2012

Reductions of the side force and the connected yawing moment are of significance for driving stability under cross wind. This paper shows the suitable body shape under unsteady cross wind for reducing side force and yawing moment. Numerically, the shape changes such as rounded and/or cut off corners and patterned indented side surface under steady cross wind are evaluated, using k-ε model. The adequate shapes from the numerical data are experimentally validated under steady and unsteady cross wind in a wind tunnel. Flow structure and, side force and yawing moment are examined by High-speed PIV and a three-component load cell, respectively.
Numerical Simulation of the Filling-Up Process of a Hydrogen Fuel Tank for Vehicular Applications
Authors: Suryan Abhilash , Kim Heuy Dong , Setoguchi Toshiaki
Published: June 2012

Hydrogen holds much promise as a source of energy that is at once abundant, clean, flexible, and secure. It is also environment friendly because it burns without producing carbon dioxide. Physical characteristics of hydrogen make it difficult to store in large quantities without taking up large amount of space. High pressure gas is a widely used storage mode for hydrogen fuel. Filling up process of a high pressure hydrogen tank should be reasonably short. The process should be designed so as to avoid high temperatures in the tank because of safety reasons. Numerical simulation can aid in optimizing the filling up process. The paper reports the numerical simulation of the filling up process of hydrogen tanks using computational fluid dynamics method. Real gas equations are solved to accurately simulate the process at the high temperature and pressure associated with the fast filling. Local temperature distribution in the tank is obtained at different durations of the fill. The numerical results obtained are validated with available experimental data.
An Analytical Approach to Improve Drag Control Techniques for the Ahmed Body
Authors: Bruneau Charles-Henri , Creuse´ Emmanuel , Depeyras Delphine , Gillie´ron Patrick , Mortazavi Iraj
Published: June 2012

The vortices generated behind a simplified vehicle induce presssure forces at the back wall that contribute to a significant part of the drag coefficient. The study shows the strong relationship between the distance of the vortices to the back wall and these pressure forces. In particular, control process can modify the trajectory of the vortices to accelerate their removal from the wall and consequently reduce the drag coefficient.
The Effects of Different Computational Domain and Several Key Issues on CFD Simulated Results for Centrifugal Pumps
Authors: Dong Liang , Liu Hou-lin , Tan Ming-gao , Wang Yong , Wang Kai
Published: June 2012

The computational domain is one of the major factors inducing CFD uncertainty. The effects of different computational domains and several key issues on CFD simulation results for centrifugal pumps are studied, such as the effects of modeling methods and boundary conditions on the whole computational domain numerical simulation. The study results indicate that the prediction accuracy of the whole computational domain is higher than that of the non-whole computational domain. The velocity distribution obtained by the whole computational domain in the gap between the impeller and volute is significantly layered, while the distribution obtained by the non-whole computational domain is triangular. The relative velocity distribution in the impeller and the turbulent kinetic energy in the volute for the two computational domains are obviously different, too. The number of the interfaces has little impact on the prediction accuracy. The rotational attribute of the chamber wall has a little effect on velocity and turbulent kinetic energy distribution, but the rotational attribute of the chamber wall can significantly improve the prediction accuracy of efficiency.
Gas-Liquid Flow Through Horizontal Eccentric Annuli: CFD and Experiments Compared
Authors: Sorgun Mehmet , Osgouei Reza E. , Ozbayoglu M. Evren , Ozbayoglu A. Murat
Published: June 2012

Although flow of two-phase fluids is studied in detailed for pipes, there exists a lack of information about aerated fluid flow behavior inside a wellbore. This study aims to simulate gas-liquid flow inside horizontal eccentric annulus using an Eulerian-Eulerian computational fluid dynamics (CFD) model for two-phase flow patterns i.e., dispersed bubble, dispersed annular, plug, slug, churn, wavy annular. To perform experiments using air-water mixtures for various in-situ air and water flow rates, a flow loop was constructed. A digital high speed camera is used for recording each test dynamically for identification of the liquid holdup and flow patterns. Results showed that CFD model predicts frictional pressure losses with an error less than 20% for all two-phase flow patterns when compared with experimental data.
Streamwise Variations in Turbulence Statistics in Drag-Reducing Turbulent Boundary Layer of Viscoelastic Fluids
Authors: Tamano Shinji , Graham Michael D. , Morinishi Yohei
Published: June 2012

Direct numerical simulation (DNS) of a zero-pressure gradient drag-reducing turbulent boundary layer of viscoelastic fluids was performed at the different Weissenberg number We = 25, 50, 75, and 100 using the FENE-P model. The increase in We, i.e. the relaxation time leads to the larger maximum of trace of conformation tensor in upstream region, and to the larger maximum of drag reduction ratio DR in downstream region, in which the trace of conformation tensor decreases gradually in the streamwise direction, while the DR increases. The trace of conformation tensor is anticorrelated with DR, While the phase difference between DR and streamwise turbulence intensity becomes larger with the increase in We. Streamwise variations in DR, turbulence statistics and structures are so different between We = 25 and We = 50 to 100, and the difference is elucidated by using the active and hibernating turbulence mechanism of Xi and Graham (2010b) for the minimal channel flow. At We = 25, the locally high and low wall-shear stress regions show larger scale compared to Newtonian fluid. On the other hand, at We = 50, regions of active and hibernating turbulence become obscurer, while the mechanism itself is unchanged.
Relationship Between Vortex Structure and Reynolds Shear Stress of Turbulent Drag Reducing Flow With Blowing Polymer Solution From the Wall
Authors: Ishitsuka Shota , Xu Hening , Motozawa Masaaki , Iwamoto Kaoru , Ando Hirotomo , Senda Tetsuya , Kawaguchi Yasuo
Published: June 2012

Relation between vortex structure and Reynolds shear stress of turbulent drag reducing channel flow with blown polymer solution was investigated by using PIV in an x-y plane. Experiment was carried out at 20000 and 40000 of Reynolds number based on the bulk mean velocity and the channel height. Blowing rate of polymer solution from the channel wall was 2.0 L/min and concentration of the polymer solution was 10, 50 and 100pmm. In the present study, calculation of the vorticity and quadrant analysis were performed to clarify the relationship between the vortex structure and Reynolds shear stress. From the result of vorticty, we found low and high speed packets which have the interaction motion fluid (Q1 and Q3). On the other hand, interaction motion increases by the polymer solution with decreasing ejection and sweep. Therefore, Reynolds shear stress decreases in order to not only decreasing ejection and sweep, but also related to increasing interaction motions. Moreover, interaction motions are amplified various intensity motion against suppression of ejection and sweep are limited to weak intensity motion. But the frequency of the interaction motions stays unchanged with drag reduction rate. The result shows characteristic structure which affects decreasing of Reynolds shear stress exists in the near-wall region.
Parametric Study of Viscoelastic Turbulence Within an Obstructed Channel Flow
Authors: Kawase Tomohiro , Tsukahara Takahiro , Kawaguchi Yasuo
Published: June 2012

The behavior of viscoelastic flow behind a two-dimensional slits was examined using direct numerical simulations (DNS). We performed DNS at five different conditions with changing the Reynolds number and the Weissenberg number, to investigate the parametric dependence of several characters of the viscoelastic flows (e.g., Toms effect and Barus effect) accompanied by the separation and reattachment. In the present conditions, the drag reduction rate was achieved from 15.1% to 19.7%. It was found that the wall-normal viscoelastic stress mainly enhanced the Barus effect in the present geometry and the streamwise viscoelastic force caused an increase of the drag. We found that, at a Weissenberg number higher than a certain level, the drag reduction rate should be decreased despite the reduced turbulent frictional drag. Moreover, we observed that, in the Newtonian flow, the spanwise vortices were dominant in a downstream region of the slits, while the streamwise vortices were dominant there in the case of the viscoelastic flow.
Measurement on the Structure of the Reynolds Stress for the Turbulent Boundary Layer Flow Over a Two-Dimensional Escarpment With Mild Upwind Slope
Authors: Shiau Bao-Shi , Tsai Ben-Jue
Published: June 2012

Experimental measurement study on the structure of the Reynolds stress and turbulence spectrum for wind flows over a two-dimensional escarpment with mild upwind slope (slope angle θ = 15°) were performed in the wind tunnel. The Quadrant analysis was applied to analyze the experimental data and yield the structure of the Reynolds stress. In according to the quadrant analysis, the Reynolds stress is composed of four events of the stress components, i.e. outward interaction, ejection (low-speed fluid upward), inward interaction, and sweep (high-speed fluid downward). Measured results show that: (1) Measurements of the structure of the Reynolds stress reveal that both the sweep and ejection events are the major contributors to the Reynolds stress for flow around the two dimensional escarpment with mild upwind slope. (2) The contributions to the Reynolds stress made by ejection events and sweep events are almost the same at heights Z/Zref greater than 0.2 for different downstream distances along the mild slope of escarpment. Here Zref is the turbulent boundary layer thickness. When flow reached the top of the slope of escarpment, stress fractions of ejection event and sweep event, S2 and S4 increased significantly. (3) The he turbulent energy spectrum distribution was not found very dominant spectrum peak as winds flow over the mild upwind slope and top surface of escarpment.
Spatial Filter Velocimetry Based on Time-Series Particle Images
Authors: Hosokawa Shigeo , Sakamoto Hiroki , Tomiyama Akio
Published: June 2012

High spatial and temporal resolutions are required in velocity measurements for turbulent flows to examine turbulence characteristics accurately. In this study, we proposed a spatial filter velocimetry (SFV) based on a frequency analysis of time-series spatially-filtered particle images. Since this method can measure velocity from one particle in a measurement region, it enables us to measure the velocity with high spatial and temporal resolutions. We developed a SFV system and applied it to laminar and turbulent flows in a duct to examine its performance. Through comparisons between the velocities measured by SFV and LDV, we confirmed that SFV accurately measures the mean velocity and turbulent intensity with spatial and temporal resolutions as high as LDV.
A Hybrid PTV Using an Affine Transformation
Authors: Doh Deog Hee , Cho Gyung Rae , Lee Chang Jae , Choi Je-Eun , Takei Masahiro
Published: June 2012

PTV (Particle Tracking Velocimetry) has been limitedly used for the measurements of flow fields because there have been interpolation data loss which is inevitable to PTV in principle. In this paper, a hybrid PTV algorithm which eliminates interpolation data losses has been constructed by using an affine transformation. In order to evaluate the performances of the constructed hybrid PIV algorithm, an artificial image test was made using the Green-Taylor vortex data. The constructed algorithm was tested on the experimental images of the wake flow (Re = 5,300) of a rectangular body (6cm × 3cm), through which its excellence was demonstrated.
High-Speed Imaging of Gas Flow by Parallel Phase-Shifting Digital Holography
Authors: Kakue Takashi , Tahara Tatsuki , Shimozato Yuki , Ito Kenichi , Awatsuji Yasuhiro , Nishio Kenzo , Ura Shogo , Kubota Toshihiro , Matoba Osamu
Published: June 2012

We succeeded in high-speed imaging of gas flow by means of parallel phase-shifting digital holography. This technique is capable of capturing three-dimensional (3-D) information of object and carrying out phase-shifting interferometry with a single-shot exposure because the interference fringe images in which the information of multiple phase-shifted holograms is spatially multiplexed are simultaneously recorded. We constructed a high-speed phase-shifting digital holography system by employing a quarter-wave plate and a high-speed camera. The image sensor of the camera has an anisotropic polarization-detecting function pixel by pixel. Each pixel of the polarization-detecting function corresponds to each pixel of the image sensor. The phase retardation of the reference wave is determined by the direction of the polarization axis of the each pixel. A compressed gas flow sprayed from a nozzle was set as an object. We attained the reconstructed images of phase variation caused by the gas flow. We also succeeded in phase imaging at the rate of 180,000 frames per second when the number of pixels of the captured image was 128 × 128. Additionally, we also obtained temporal subtraction images of the reconstructed images. The achieved frame rate was the fastest among not only phase-shifting digital holography but also digital holography and phase-shifting interferometry which have been ever reported, for our knowledge. It is expected that parallel phase-shifting digital holography and the constructed system can contribute to 3-D moving picture measurement of dynamically moving objects such as particle flows, shock waves, mechanical vibration, and so on.
Flow Characteristics of Fluid Droplet Obtained From Air Assisted Atomizer
Authors: Watanawanyoo Pipatpong , Mochida Hirofumi , Hirahara Hiroyuki , Chaitep Sumpun
Published: June 2012

Air assisted atomizer system was designed and developed for fuel injection. The present purpose is to utilize a low pressure in supplying of atomized fuel. Distilled water was used as test liquid on the experiments for the system of atomization. The results revealed air assisted atomizer had a capability to inject the test liquid in the range of the rates of 0.0019–0.00426 kg/s, with the use of air pressure supplied from 68.9 to 689 kPa. In this research, the test liquid supply pressure was kept constant and the air flow rate through the atomizer was varied over a range of air supply pressure to obtain the variation in air liquid mass flow ratio (ALR). The spray solidity was studied by taking pictures of the spray at different liquid air supply pressures. The experimental investigations suggest that spray cone angle tends to increase with increasing in air liquid mass flow ratio because the kinetic energy of the flow keeps on increasing. The solid cone spray has a pattern of penetration depth between 408–446 mm. and cone angle between 14.5–23.6°. It was observed that spray formed the solid cone at all the operating conditions.
Solids Mobilization and Suspension by Dual Opposed Mixing Pumps
Authors: Bamberger Judith Ann , Fort James A. , Enderlin Carl W.
Published: June 2012

Experiments were performed to support understanding mixing of Tank 241-SY-101 at the Hanford Site in Washington State. These experiments were conducted at 1/12 scale and modeled the tank and proposed mixing pump. The tests investigated solids mobilization and suspension for jets rotated in fixed increments about the tank centerline. Flow visualization tests showed that the supernatant layer was generally too cloudy for effective visualization. Observations of the settled solids interface during a start-up transient showed that the mixing action was always confined within the slurry layer. A 4.57-m/s (15-ft/s) jet velocity was not capable of clearing settled sludge off the tank floor all the way to the tank wall and produced a stratified flow field at steady state; 7.62-m/s (25-ft/s) and higher jet velocities always circulated solids to the tank surface. During the operating parameter tests with jets rotated at fixed increments, the slurry interface rose more slowly than for the fixed location jets. Solids suspension was more effective for the rotated jets than for the fixed location jets. Percent solids suspended with a 7.62-m/s (25-ft/s) jet was 66 to 72% in the high viscosity simuant and 59 to 67% in the low viscosity stimulant. Percent solids suspended with a 15.2 m/s (50-ft/s) jet was 74 to 81% in the low viscosity stimulant. A 7.62 m/s (25-ft/s) jet velocity was adequate to clear settled solids from the tank floor to the tank wall for both the low and high viscosity stimulant.
Digitalization of High Accuracy Thermo-Anemometer for Heat Flux Measurement in Stratified Flow
Authors: Sanae Shunichi , Ohba Katsuhisa
Published: June 2012

In this study, the high-accuracy thermo-anemometer was developed to execute simultaneous measurement of temperature and velocity by employing Field Programmable Gate Array (FPGA) devices. A cold-wire temperature sensor has first-order lags due to thermal time constants, that means that a phase compensation is essential to measure temperature fluctuations with high frequency. The digital filter comprised the exact first-order lead characteristics was realized by the bilinear s-z transformation. It was verified that the temperature signals were appropriately compensated with an uncertainty of less than ±3.9% in frequency up to 10 kHz. For velocity measurements, a temperature compensation is indispensable owing to velocity and temperature dependence of response of a hot-wire anemometer in thermally stratified flow fields. The accuracy of the velocity measurements at high temperature was improved with the strict algorithm of the temperature compensation calculation incorporating the temperature dependence of the thermal properties of the air. The high-accuracy velocity measurement was realized within the accuracy of ±1.6% in the temperature range of 1.5 times as wide as that of the previous analog based system. The simultaneous measurement system for temperature and velocity was applicable to measure heat flux in thermally stratified flows.
Non-Newtonian Fluid Cavern and Newtonian Cloud Height Tests to Characterize Pulse Jet Mixer Operation
Authors: Enderlin Carl W. , Bontha Jagannadha R. , Bamberger Judith Ann , Nigl Franz
Published: June 2012

Pulse jet mixing systems are being developed for use in the Waste Treatment Plant in Washington State. To assist with system development, scaled tests were conducted to obtain experimental measurements of the cloud height for Newtonian slurries and cavern heights for a Non-Newtonian yield stress material. The measurements were required to assess the effective mixing and material mobilization produced during pulse jet mixer operation. The cloud height measurements were obtained for a single steady-state jet directed downward in a spherical-bottom tank. The cloud tests used glass beads in water to evaluate the height of the suspended slurry as a function of jet velocity. Cloud testing revealed that the glass bead material was suspended in the tank quickly and developed a distinctive height for each combination of flow rate and particulate size tested. The solids loading had minimal impact on the cloud height for a given particle size. During all cloud tests, the surface of the tank remained relatively calm, indicating that the slurry was dissipating the mixing energy of the relatively high velocity jet. Cavern tests were conducted to obtain experimental data of non-Newtonian fluid mixing for fluid properties similar to those of certain tank wastes. A transparent material that exhibited a yield stress and shear thinning behavior was used to obtain measurements of steady-state cavern heights as a function of jet velocity. For the non-Newtonian fluid cavern tests, distinct cavern volumes were readily developed for the four velocities tested. A linear relationship was observed to exist between cavern height and nozzle velocity. Since the experimental work detailed in this paper was completed, additional scaled tests have been conducted with pneumatic drive systems and direct drive systems similar to that described for this effort. Data from both types of measurements are shown to be linear; however, effects from the reciprocating drive systems that are not yet incorporated into models may be affecting the ability to collapse this data independent of scale. It is recommended that future efforts to assess performance of PJM operations using scaled tests consider employing direct drive systems to aid in evaluating scaling trends. A test system can be configured to allow testing at both reciprocating and direct drive conditions; thereby allowing direct comparison between them.
Cavitation From a Butterfly Valve: Comparing 3D Simulations to 3D X-Ray Computed Tomography Flow Visualization
Authors: Brett Graham , Riveland Marc , Jensen Terrence C. , Heindel Theodore J.
Published: June 2012

Flow control valves may experience localized cavitation when the local static pressure drops to the liquid vapor pressure. Localized damage to the valve and surrounding area can occur when the vapor cavity collapses. Valve designs that reduce cavitation are based on empirical evidence and accumulated experience, but there are still considerable cavitation problems in industry. Valve designers may use computational fluid dynamics (CFD) to simulate cavitation in flow control valves, but model validation is challenging because there are limited data of local cavitation from the valve surface. Typically, the intensity of cavitation in a control valve is inferred from measurements of observable side effects of cavitation such as valve noise, vibration, or damage to the valve assembly. Such an indirect approach to characterizing cavitation yields little information about the location, degree, and extent of the cavitation flow field that can be used in CFD validation studies. This study uses 3D X-ray computed tomography (CT) imaging to visualize cavitation from a 5.1 cm diameter butterfly valve and compares the resulting vapor cloud to that predicted by CFD simulations. Qualitative comparisons reveal that the resulting cavitation structures are captured by the simulations when a small amount of non-condensable gas is introduced into the fluid and the simulations are completed in a transient mode.
A Study on the Cause Investigation of the Local Pipe Wall Thinning in the Downstream of an Orifice Through the UT Data and Numerical Analysis
Authors: Hwang Kyeong Mo , Yun Hun , Lee Chan Kyoo
Published: June 2012

Piping systems in nuclear power plants are affected by degradation mechanisms such as FAC (Flow-Accelerated Corrosion), Cavitation, Flashing, LDI (Liquid Droplet Impingement) and the like. FAC is well-known degradation mechanism. Most nuclear power plants, therefore, implement inspection programs to detect and control damages by FAC. On the other hand, various erosion mechanisms occurring on piping lines and local components lead to wear, leaks, and failures on piping systems. This paper describes intensive wear phenomenon on pipes, elbows, and tees located in upstream of heat exchangers. In the beginning of the study, it appeared to be flow cavitation damages. This is because the orifice is installed in the upstream section of a damaged elbow. After reviewing the damaged surface, it turned out that flow cavitation was not the key issue in this case. It is supposed that shock focusing effect, related to the bubbles that are created by vibration of a pump impeller, is the main reason of this intensive wear. The phenomena of shock focusing effect are known to have resulted from the pressure concentration due to collapsing bubbles in liquid.
Nonlinear Propagation of Sound Beam in Nonuniform Bubbly Liquids
Authors: Kanagawa Tetsuya , Yano Takeru , Kawahara Junya , Kobayashi Kazumichi , Watanabe Masao , Fujikawa Shigeo
Published: June 2012

Nonlinear propagation of weakly diffracted sound beams in a weakly nonuniform bubbly liquid is analytically studied based on the method of multiple scales and scaling relations of some physical parameters. The system of basic equations consists of the conservation equations of mass and momentum for gas and liquid in a two-flui model, the Keller equation for bubble wall, the state equations for gas and liquid, and so on. The compressibility of liquid is taken into account and this leads to the wave attenuation due to bubble oscillations. It is assumed that the spatial distribution of the number density of bubbles in an initial state at rest is a slowly varying function of space coordinates and the amplitude of its variation is small compared with a mean number density. As a result, a Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation with dispersion and nonuniform effects for a low frequency and long wavelength case and a nonlinear Schro¨dinger (NLS) equation with dissipation, diffraction, and nonuniform effects are derived from the basic equations.
Luminescent Spots Induced by a Cavitating Jet
Authors: Soyama Hitoshi
Published: June 2012

As cavitation bubble collapses cause hot spots and/or radicals such as hydroxyl radical, luminescence was observed at bubble collapsing region. The luminescence induced by acoustic cavitation is named as sonoluminescence. In the present paper, luminescence induced by hydrodynamic cavitation was investigated. In order to generate hydrodynamic cavitation, a high-speed water jet was injected into a water-filled chamber. This sort of the jet with cavitation is called as a cavitating jet. The intensity of luminescence of the cavitating jet was evaluated by a luminescence analyzer and the aspect of the cavitating jet was observed by a cooled electron multiplication charged-coupled device camera. It was revealed that the luminescent spots induced by the cavitating jet were observed by the camera.
Ultrasound Beam Radiated From Circular Piston in Bubbly Liquids: Nonlinear Analysis for Envelope of Short Waves With Diffraction Effect
Authors: Kawahara Junya , Kanagawa Tetsuya , Yano Takeru , Kobayashi Kazumichi , Watanabe Masao , Fujikawa Shigeo
Published: June 2012

A weakly diffracted ultrasound beam radiated from a circular piston placed in a bubbly liquid is formulated in terms of a wave equation based on scaling relations of physical parameters [1]: typical propagation speed, period, wavelength, and diameter of beam. We derive a nonlinear evolution equation for the modulation of quasi-monochromatic waves for the case of a short wavelength with a moderately high frequency from a set of basic equations for bubbly flows: conservation equations of mass and momentum for gas and liquid in a two-fluid model, Keller’s equation for bubble wall motion, state equations for gas and liquid, and so on. The compressibility of liquid is taken into account, and thus the waves are attenuated due to bubble oscillations. The viscosity of gas, heat conduction in gas and liquid, and phase change across bubble wall are ignored. As a result, the nonlinear Schro¨dinger equation for the envelope of the beam with diffraction effect is derived from the basic equations. For plane waves the diffraction term does not appear, and hence our equation is reduced to the original nonlinear Schro¨dinger equation [1].
Numerical Investigation on the Structure of High-Speed Cavitating Water Jet Issuing From an Orifice Nozzle
Authors: Peng Guoyi , Ito Hideto , Shimizu Seiji , Fujikawa Shigeo
Published: June 2012

A practical mixture flow approach to the numerical simulation of turbulent cavitating flows is developed by coupling a simplified estimation of bubble cavitation to a compressible mixture flow computation. The mean flow of two-phase mixture is calculated by neglecting the slip between bubbles and surround liquid. Navier-Stokes equations for compressible fluids are used to describe the unsteady mean flow field and the RNG k-ε model is adopted for modeling of the flow turbulence. The intensity of cavitation in a local field is evaluated by the volume fraction of gas phase varying with the mean flow. The flow structure of submerged water jets issuing from an orifice nozzle is investigated numerically. Both non-cavitating and cavitating jets are calculated under different cavitation numbers in order to clarify the cavitation property of submerged water jet. The results demonstrate that the intensity of cavitation denoted by the maximum value of gas volume fraction and the area of strong cavitation indicted by high value of gas volume fraction increase with the decrease of cavitation number. Under the effect of cavitation bubbles the discharge coefficient of orifice nozzle decreases with the cavitation number.
Introduction of Comprehensive Learning-Type Class: An Example—Fluid Mechanics Class
Authors: Sugimoto Yasuhiro , Sato Keiichi
Published: June 2012

Kanazawa Institute of Technology (KIT) started an education reform for new century from 1995. After that, around 2007, based on “Comprehensive Learning Initiative Process” (CLIP), “Comprehensive Active Learning-type Education” (CAL-E) has been introduced. The CAL-E aims at training engineering students’ comprehensive abilities to nurture them becoming competent engineers for society. There are several class formats within CAL-E program, they are “presentation,” “discussion on a topic” and “practice and seminar.” Depending on the objective and role of subjects, the best type of CAL-E class format is conducted accordingly. In this paper, we use Fluid Mechanics classes as an example to demonstrate the effectiveness of CAL-E-oriented classes and examine its effect on students through a questionnaire.
An Estimation of Thermodynamic and Transport Properties of Cryogenic Hydrogen Using Classical Molecular Simulation
Authors: Nagashima Hiroki , Tokumasu Takashi , Tsuda Shin-ichi , Tsuboi Nobuyuki , Koshi Mitsuo , Hayashi A. Koichi
Published: June 2012

In this paper, we estimated the thermodynamic and transport properties of cryogenic hydrogen using classical molecular simulation to clarify the limit of classical method on the estimation of those properties of cryogenic hydrogen. Three empirical potentials, the Lennard-Jones (LJ) potential, two-center Lennard-Jones (2CLJ) potential, and modified Buckingham (exp-6) potential, and an ab initio potential model derived by the molecular orbital (MO) calculation were applied. Molecular dynamics (MD) simulations were performed across a wide density-temperature range. Using these data, the equation of state (EOS) was obtained by Kataoka’s method, and these were compared with NIST (National Institute of Standards and Technology) data according to the principle of corresponding states. Moreover, we investigated transport coefficients (viscosity coefficient, diffusion coefficient and thermal conductivity) using time correlation function. As a result, it was confirmed that the potential model has a large effect on the estimated thermodynamic and transport properties of cryogenic hydrogen. On the other hand, from the viewpoint of the principle of corresponding states, we obtained the same results from the empirical potential models as from the ab initio potential, showing that the potential model has only a small effect on the reduced EOS: the classical MD results could not reproduce the NIST data in the high-density region. This difference is thought to arise from the quantum effect in actual liquid hydrogen.
Liquid-Liquid Interfacial Flow Structure Obtained From Nano-PIV/LIF
Authors: Iino Masao , Hasegawa Atsuto , Shimizu Hiroyuki , Sato Yohei
Published: June 2012

The flow structure at liquid-liquid interface was investigated by PIV/LIF with evanescent wave illumination. Laminar parallel flow comprising buffer solution and oil was formed in a microchannel. The laser beam was introduced into oil by a two-prism system and was totally reflected at the buffer solution-oil interface. The evanescent wave penetrates into the solution as a light source. The interfacial velocity measurement of solution was performed by nano-PIV. In prior to apply nano-LIF to measurement of an electrostatic potential distribution at the interface, a representative electrostatic potential was obtained from measurements of elelctroosmotic mobility of the buffer solution.
Flow Visualization Around Actuating Valve of Micro-Vibrating Flow Pump
Authors: Osman Osman Omran , Shintaku Hirofumi , Kawano Satoyuki
Published: June 2012

In this paper, we propose a novel micropump, so-called micro vibrating flow pump (micro-VFP). Micro-VFP consists of a microchannel and an actively vibrating valve which has a cantilever like structure fixed on a wall of a microchannel. This valve works as an actuator for liquid flow in the microchannel. Since the valve is made of a flexible material including magnetic particles, it can be deformed by externally applying the magnetic field. After removing the magnetic field, the valve returns back to its original position by its own elasticity. By periodically changing the magnetic field, the valve vibrates and gives kinetic energy to the liquid. Furthermore, we designed sleeves on the side walls of the microchannel in the downstream of the valve. By adding the sleeves, the valve vibrates asymmetrically to generate net flow in one direction. To investigate the basic performance of micro-VFP, a prototype one is fabricated using soft lithography processes. The flow dynamics around the actuating valve is investigated in detail using particle image velocimetry.
Micro-PIV Measurement on Transient Flows in Pneumatic MEMS Device for Cell Trapping
Authors: Kim Hyun Dong , Kim Kyung Chun
Published: June 2012

This paper presents a micro-PIV measurement for investigation of flow characteristics in a micro chamber for trapping of a live cell. The micro cell chip consisting of pneumatic vibrator arrays and a trap chamber was fabricated through a replica molding technology with a SU-8 mold and Polydimethylsiloxane (PDMS) polymer. The single cell in the trap chamber was manipulated and trapped in the equilibrium region by exploiting the geometrical symmetry of the vibrators. The x-axial velocity of the viscous fluid induced by the deformation of the flexible diaphragms was eliminated or minimized at the center of vibrators. From the measurement results, the proper operational conditions of the vibrators were determined and it is also verified that the particle can be actively manipulated and trapped as desired.
High-Speed Pulsed Mixing With High-Frequency Switching of Pumping From Three Micropumps
Authors: Sugano Koji , Nakata Akihiro , Yoshimune Hideaki , Hirai Yoshikazu , Tsuchiya Toshiyuki , Tabata Osamu
Published: June 2012

In this study, we proposed a novel mixing method using alternate pulsed flows from three inlet channels using three piezoelectric valveless micropumps. Two solutions are assigned into one micropump and the other two micropumps, respectively. The fabricated microfluidic device consists of a cross-shaped mixing channel with three inlet microchannels and three valveless micropumps. According to the experimental results, it was confirmed that the pulsed mixing using three inlet microchannels increased mixing speed with increasing the switching frequency of the micropump driving up to 200 Hz. The proposed method solved the problem of a bias of concentration ratio near the sidewalls which has happened in the previous pulsed mixing method using T- or Y-shaped microchannel with two inlet microchannels. Furthermore, by controlling a solution flow at the confluent area utilizing a reverse flow of the micropump, the mixing speed dramatically increased and the mixing time of 3.6 ms for 90% mixing ratio was achieved at the micropumps switching of 400 Hz.
Development of a Three Dimensional Passive Lamination Micromixer
Authors: Nakahara Tasuku , Ootani Norifumi , Asanuma Toshiyuki , Hagio Yoshinori , Hiramaru Daisuke , Terao Kyohei , Okonogi Atsuhito , Oohira Fumikazu , Kotera Hidetoshi , Suzuki Takaaki
Published: June 2012

In this paper, we propose a three-dimentional multi-layered flow generator fabricated by inclined UV lithography to expose a single layerded photoresist coated on a patterned mask. To confirm the validity of the proposed generator, we applied the three-layered flow generator as a passive lamination micromixer. By comparing two types of fabricated micromixers, the three-layered micromixer achieves 1.64 times faster mixing rate than a conventional Y-shaped one due to the shortening of the diffusion length. The fabricated flow generator can be applied for a passive micromixer with laminated and/or secondary flows, a sheath flow generator, and a multi-layered emulsion system.
Numerical Simulation of Adiabatic Two-Phase Flow in Micro-Channels
Authors: La Forgia N. , Fernandino M. , Dorao C. A.
Published: June 2012

Compact and efficient heat exchangers are needed to obtain energy efficient processes. An optimal design and operation of such systems require improving the physical understanding of the complex two-phase flow phenomena. The complexity of the evaporation process has been widely acknowledged, and several descriptions have been proposed with special focus on the micro region between the bubble interface and the heated wall [1,2,3]. In the case of evaporation in micro channels and as a consequence of the large interfacial area to volume ratio, some factors such as surface tension, frictional pressure drop, nucleation, etc. are playing an important role, and thus cannot be neglected. The prediction of the behavior of micro-scale two-phase evaporation is still limited. While experimental studies [4] have provided valuable insight of the phenomena, due to limitations in the experimental conditions all aspects of the micro scale boiling flow are not completely understood. In this sense, a computational approach can help to complement experimental studies. However the simulation of micro scale flow has several challenging aspects such as the tracking of the bubble interface, introduction of the surface tension effects, subscale modeling of the micro region, and the like. The goal of this work is to discuss the development of a computational model for studying micro scale evaporation phenomena and bubble dynamics in micro scale boiling and flowing. The model is based on a continuum surface force (CSF) model which belongs to the family of diffuse interface methods. A particular aspect of this work is the subgrid modeling of the micro scale region and its coupling to the macro scale flow. The mathematical model is solved using a spectral element method which provides a good balance between accuracy and computational cost.
An Integrated Micro/Nanofluidic System for Processing of Protein Samples
Authors: Anwar Khalid , Han Taeheon , Kim Sun Min
Published: June 2012

In this study, an integrated micro/nanofluidic system for protein analysis was presented. The device is comprised of a micromixer and a preconcentrator with a separation column. The integrated micromixer based on unbalanced split and cross collision of fluid streams is passive and planar, which is easy to fabricate and integrate to the microfluidic system. The preconcentrator has nanochannels formed by the electrical breakdown of polydimethylsiloxane (PDMS) membrane using a high electrical shock, without any nano-lithographic process. Micromixer and preconcentrator were used for sample preparation (tagging of protein for detection) and concentration of protein, consecutively. Proteins were electrokinetically trapped near the junction of micro/nanochannels.
Optical Film Thickness Measurements Using a Reflectance Mode Swept-Field Confocal Microscope
Authors: Hernandez Joseph E. , Allen Jeffrey S.
Published: June 2012

Multiphase flow in microchannels is frequently encountered in microdevices. Predicting the behavior of the multiphase flow has been difficult. The dynamics of liquid films inside of capillaries is important to microfluidic flows. At high flow rates with gas-liquid flows, the dynamics of liquid films on the interior surfaces of the microchannels can have a global affect on device operation. Measurement via optical microscopy of velocities in these liquid films and interface dynamics has been hampered by the inability to correctly image near dyanamic interfaces due to optical reflection and very short time scales of the flow. A novel technique for optically measuring liquid film thicknesses within circular microchannels has been developed. A swept-field confocal microscopy unit has been modified to capture the reflected light by replacing the dichroic mirror, commonly used in fluorescence confocal microscopy, with a 50/50 beam splitter. “Optical slicing” in the x-y plane, coupled with precision z-axis stepping allows for the detection of the gas-liquid interface by blocking out-of-focus light.
The Human Gut Microbiota and Undernutrition
Authors: Gordon Jeffrey I. , Dewey Kathryn G. , Mills David A. , Medzhitov Ruslan M.
Published: June 2012

Elucidating the relationship between breast milk and the developing infant gut microbiota and immune system will provide new insights into malnutrition.
Characterization of a Novel IMP-28 Metallo-β-Lactamase from a Spanish Klebsiella oxytoca Clinical Isolate
Authors: Pérez-Llarena Francisco José , Fernández Ana , Zamorano Laura , Kerff Frédéric , Beceiro Alejandro , Aracil Belén , Cercenado Emilia , Miro Elisenda , Oliver Antonio , Oteo Jesús , Navarro Ferran , Bou Germán
Published: June 2012

An isolate of
Klebsiella oxytoca
carrying a novel IMP metallo-β-lactamase was discovered in Madrid, Spain. The
bla
IMP-28
gene is part of a chromosomally located class I integron. The IMP-28
k
cat
/

K
m

values for ampicillin, ceftazidime, and cefepime and, to a lesser extent, imipenem and meropenem, are clearly lower than those of IMP-1. The His306Gln mutation may induce important modifications of the L3 loop and thus of substrate accessibility and hydrolysis and be the main reason for this behavior.
Escherichia coli: Great Diversity around a Common Core
Authors: Moriel Danilo G. , Rosini Roberto , Seib Kate L. , Serino Laura , Pizza Mariagrazia , Rappuoli Rino
Published: June 2012

The 2011
Escherichia coli
outbreak in Germany, which resulted in more than 4,000 cases, including 908 cases of hemolytic-uremic syndrome (HUS) and at least 50 deaths, highlighted the genome plasticity of
E. coli
and the potential for new virulent strains to emerge. The analysis of 170
E. coli
genome sequences for the presence of nine previously identified protective extraintestinal pathogenic
E. coli
antigens suggested the feasibility of a combination vaccine as a universal intervention against all pathogenic
E. coli
strains.

IMPORTANCE
This article reports on the feasibility of a combination vaccine as a universal intervention against all pathogenic
Escherichia coli
strains.
Clostridium septicuminfection in a young pregnant patient: Figure 1
Authors: McDonald Rachel E , Moola Shiraz
Published: June 2012

This report describes a young pregnant woman who presented to a rural emergency department with vaginal bleeding at 7 weeks of gestation. Initially, the patient was stable; however, within 8 h the patient deteriorated into fulminant septic shock. She required aggressive resuscitation and surgical management of a septic abortion. The patient's condition improved rapidly following surgical evacuation of the uterus with dilatation and curettage. She has had no long-term sequelae. Blood and tissue cultures returned positive forClostridium septicum. To the best of our knowledge, this is the only reported case of survival fromC septicuminfection in a pregnant woman and highlights the importance of improved awareness and management of such infections by the medical community so that future cases can achieve similarly successful outcomes.
Recurrent retroperitoneal liposarcoma in a patient with neurofibromatosis type I
Authors: Gomez Carrie K , Rosen Gerald , Mitnick Robin , Chaudhri Ali
Published: June 2012

Introduction

Liposarcoma complicating neurofibromatosis is very rare. Only a few cases have been described until now. We present a case of recurrent dedifferentiated retroperitoneal liposarcoma in a patient with neurofibromatosis type I (NF-1).

Case presentation

A 47-year-old Caucasian woman with  NF-1 presented to the hospital initially complaining of left lumbar pain irradiating to the anterior thigh and knee. Physical examination showed atrophy of the lower extremities bilaterally and decreased motor strength on the left lower extremity. Radiological studies demonstrated an enhancing lesion in the left paraspinal region, suggesting malignancy. The patient underwent local resection of tumour with safety margins. Pathological examination was consistent with dedifferentiated liposarcoma (DDLS) with positivity for MDM2 and CDK4 markers. No evidence of metastasis was noted on the radiological studies. The final diagnosis was DDLS, high-grade (G3), pT2bN0M0, stage III. After 6 weeks post-tumour resection, the patient experienced recurrence of malignancy. Chemotherapy with cisplatin and doxorubicin was initiated in the patient.

Conclusions

Liposarcoma in the context of neurofibromatosis is very rare. To the best of our knowledge, only six cases have been reported until now in the literature. We are presenting this case to underline the possibility of recurrence in the case of retroperitoneal DDLSs despite local tumour resection. Also, although the role of chemotherapy is controversial we decided to start treatment with cisplatin and doxorubicin given the success of chemotherapy in similar case presentations.
JAK/STAT3 pathway inhibition blocks skeletal muscle wasting downstream of IL-6 and in experimental cancer cachexia
Authors: Bonetto Andrea , Aydogdu Tufan , Jin Xiaoling , Zhang Zongxiu , Zhan Rui , Puzis Leopold , Koniaris Leonidas G. , Zimmers Teresa A.
Published: June 2012

Cachexia, the metabolic dysregulation leading to sustained loss of muscle and adipose tissue, is a devastating complication of cancer and other chronic diseases. Interleukin-6 and related cytokines are associated with muscle wasting in clinical and experimental cachexia, although the mechanisms by which they might induce muscle wasting are unknown. One pathway activated strongly by IL-6 family ligands is the JAK/STAT3 pathway, the function of which has not been evaluated in regulation of skeletal muscle mass. Recently, we showed that skeletal muscle STAT3 phosphorylation, nuclear localization, and target gene expression are activated in C26 cancer cachexia, a model with high IL-6 family ligands. Here, we report that STAT3 activation is a common feature of muscle wasting, activated in muscle by IL-6 in vivo and in vitro and by different types of cancer and sterile sepsis. Moreover, STAT3 activation proved both necessary and sufficient for muscle wasting. In C2C12myotubes and in mouse muscle, mutant constitutively activated STAT3-induced muscle fiber atrophy and exacerbated wasting in cachexia. Conversely, inhibiting STAT3 pharmacologically with JAK or STAT3 inhibitors or genetically with dominant negative STAT3 and short hairpin STAT3 reduced muscle atrophy downstream of IL-6 or cancer. These results indicate that STAT3 is a primary mediator of muscle wasting in cancer cachexia and other conditions of high IL-6 family signaling. Thus STAT3 could represent a novel therapeutic target for the preservation of skeletal muscle in cachexia.