bluuebunny/crossref_metadata_2025 huggingface dataset:
The Method of Autonomous Statistical Modeling ASMTurb and its Testing on the Example of Classical Turbulent Flows
Authors: Nuzhnov Yu. V.
Published: June 2016

A physical designation of the method of autonomous statistical modeling turbulent flows (ASMTurb method with consideration of external intermittency) and its testing are presented. The method is tested on the example of constructing of mathematical models for self-similar turbulent shear flows such as: I-the two-stream plane mixing layer; II-the outer region of the boundary layer on the wall; III-the far wake behind a cross-streamlined cylinder; IV-the axisymmetric submerged jet. Test results are presented in the form calculating the main conditional and total statistical averages applied to self-similar region of turbulent flows. It is shown that the ASMTurb models which constructed here are more accurate and more detailed than RANS models. A comparison is made between predictions and known experimental data for energy-containing structure of turbulent flow and excellent agreements are noted.
Flow and Decay Characteristics of Submerged Yield-Pseudoplastic Jets
Authors: Hammad Khaled J.
Published: June 2016

The flow structure and decay characteristics of submerged yield-pseudoplastic jets are investigated. Numerical solutions to the governing mass and momentum conservation equations, along with the Herschel-Bulkley rheological model, are obtained using a finite-difference scheme. A large recirculation region exists for Newtonian and pseudoplastic non-Newtonian jets. However, the extent and strength of the recirculation region substantially diminish with the yield number and, to a much lesser extent, when the shear-thinning index is decreased from 1 to 0.6. Increasing the yield number beyond a critical value eliminates flow recirculation. The centerline velocity and momentum decay of yield-pseudoplastic jets, in general, increase with the yield number. The impact of shear-thinning on the flow structure and decay characteristics of the jet is more pronounced at low yield numbers.
Pressure Drop Testing of Corrugated Stainless Steel Pliable Gas Tubing (PLT)
Authors: Srinivasan Bharadwaj , Idem Stephen A.
Published: June 2016

Pressure loss tests were conducted on straight corrugated stainless steel pliable gas tubing (PLT) per I.S. EN 15266:2007 [1]. A power law least-squares curve fit was used to relate pressure loss per unit length as a function of volume flow rate. For every case considered the calculated coefficient of determination values exceeded 0.90, indicating suitable correlation. Based on the curve fit expressions gas discharge graphs for the volume flow that would yield a pressure loss of 1 mbar were generated as a function of PLT length and diameter. Darcy friction factors were calculated from test data for each case and plotted on the Moody diagram as a function of Reynolds number based on the minimum PLT cross section. For Reynolds numbers less than 2300 the pressure loss data for PLT yielded an inverse relationship between the Darcy friction factor and the Reynolds number. In those instances the proportionality coefficient equaled 49, which differs from the value of 64 that can be derived analytically for steady laminar flow in a uniform cross section horizontal pipe.
Wavelet Analysis of Finite Height Grid Turbulence Over a Flat Plate
Authors: Fouladi F. , Henshaw P. , Ting D. S-K.
Published: June 2016

An experimental investigation was carried out in a wind tunnel in order to study the turbulent flow over a flat plate that is a scaledown of a photovoltaic (PV) panel. By inducing turbulence in the flow over a PV panel, its convective heat loss can be increased. The turbulence was generated by a plate with diamond-shaped perforations (grid), which was mounted vertically at the leading edge of the flat plate. Fourier and wavelet transforms are utilized to study the turbulence downstream of the grid at specific points. Results showed that at the height of the upper edge of the grid, turbulence has a higher kinetic energy than at the points behind the grid. For the points behind the grid, at all eddy size ranges, turbulence energy decayed significantly with downstream distance. For the points at grid height, it seems that for large eddies (frequency lower than 100 Hz) the energy increased in the downstream direction and for other ranges it decreased very slightly. This analysis may influence the design of passive flow devices meant to enhance the heat transfer from a PV panel’s surface.
Viscoelastic Rotating Flow With Viscous Dissipation
Authors: Hazbavi A. , Ashrafi N. , Najafi M.
Published: June 2016

The rotational flow of pseudoplastic fluids between concentric cylinders is examined while dissipation due to viscous effects is taken into account. The viscosity of fluid is dependent on shear rate only. The shear rate dependence of viscosity is modeled according to the Carreau equation. Hydrodynamically, stick boundary conditions are applied and thermally, both constant temperature and constant heat flux on the exterior of cylinders are considered. The governing motion and energy balance equations are coupled adding complexity to the already highly correlated set of differential equations. Introduction of Brinkman number has maintained a nonlinear base flow between the cylinders. As well, the condition of constant heat flux has moved the point of maximum temperature towards the inner cylinder. In the presence of viscous heating, the effect of parameters such as Deborah and Brinkman numbers, material time and pseudoplasticity constant is presented. The flow parameters along with viscosity maps are given for different scenarios of the flow.
Numerical Study of Drag Forces in Gravity-Induced Separation for Water Dominated Dispersed Oil-Water
Authors: Caldera Elionora A. , Asuaje Miguel
Published: June 2016

In recent years, the oil sector has been struggling with the amount of water produced associated with the total volume of oil production. This quantity is known as water cut and could be over 90% in oil extraction. Handling of this water generates additional costs, affecting the sector’s revenues. In order to solve this problem, several techniques to reduce water cut in the wellbore have been applied.

This paper evaluates CFD (computational fluid dynamics) models to predict phase segregation in dispersed oil in water flows. This evaluation has been conducted in an attempt to use CFD models to improve the design methodology of an inline separator of oil-water flow for petroleum production systems [1].

In this 3D study, three cases simulating water dominated dispersed oil-water flow in an inclined pipe 45° from horizontal, were evaluated numerically using a CFD model The oil was considered as the disperse phase and the water as the continuous phase, using Ansys®CFX. Mono size droplet dispersion was employed to represent the dispersed phase. The equations for the forces considered in this study are: drag and buoyancy.

The simulated results are compared with the experimental data, which includes water volume fraction, drop pressure and separation efficiency. The result shows an improvement of over 50% in the experimental values, which match the values of the total flow rate (Q), water holdup (Hw) and pressure drop (ΔP), deviating by less than 4%.
Large Eddy Simulation of Round Impinging Jets With Large Stand-Off Distance
Authors: Shademan Mehrdad , Roussinova Vesselina , Barron Ron , Balachandar Ram
Published: June 2016

Large Eddy Simulation (LES) has been carried out to study the flow of a turbulent impinging jet with large nozzle height-to-diameter ratio. The dynamic Smagorinsky model was used to simulate the subgrid-scale stresses. The jet exit Reynolds number is 28,000. The study presents a detailed evaluation of the flow characteristics of an impinging jet with nozzle height of 20 diameters above the plate. Results of the mean normalized centerline velocity and wall shear stress show good agreement with previous experiments. Analysis of the flow field shows that vortical structures generated due to the Kelvin-Helmholtz instabilities in the shear flow close to the nozzle undergo break down or merging when moving towards the plate. Unlike impinging jets with small stand-off distance where the ring-like vortices keep their interconnected shape upon reaching the plate, no sign of interconnection was observed on the plate for this large stand-off distance. A large deflection of the jet axis was observed for this type of impinging jet when compared to the cases with small nozzle height-to-diameter ratios.
Study on Pressure Pulsation in the Volute of a Centrifugal Pump by Large Eddy Simulation
Authors: Zhang Yuan , Zhang Yongxue , Zhang Jinya , Hou Hucan
Published: June 2016

Pressure pulsation caused by unsteady flow plays one of the most important roles in the stable operation of centrifugal pumps. Numerical simulation method of LES (Large Eddy Simulation) with WALE model has been used to calculate the unsteady flow in IS150-125-250 centrifugal pump passages. Three groups monitoring points distributed on 8 cross sections in different radial, circumferential, axial directions were set. And pressure pulsation in volute with different flow rates, radial distance, circumferential angles and axial distance was studied. Changing of the maximal pressure pulsation amplitude on monitoring points has been obtained by time and frequency domain analysis. The research demonstrated the maximum amplitude of pressure pulsation is located at the volute tongue, and its magnitude changes with flow rates at each monitoring point. The dominant frequency of pressure pulsation in the volute is equal to the blade passing frequency and the sub-dominant frequencies are also related to the blade passing frequency. The periodicities of circumferential pressure pulsations at different monitoring points in the volute are similar. More deviation of design flow rate results in larger pressure pulsation amplitude. Increasing radius will weaken pressure pulsation amplitude while closing to the wall of volute can strengthen the pressure pulsation. The research of pressure pulsation in volute will show great help in hydraulic design of centrifugal pump to realize longer component life, less vibration and more stable operation.
Fiber Supplemented Droplet Diving Into Two Liquid Layers
Authors: Harris Alyssa , Su Tsung-chow
Published: June 2016

In an exploratory experiment, utilizing a flow visualization technique, a droplet of water was supplemented with fiber and released into a container of liquid. The liquid inside container consisted of a thin layer of oil laid on top of the water, in which a small amount of bromothymol-blue indicator was added. The liquid droplet also contained a dilute solution of NaOH along with the small amount of fiber supplement. Thus, as the droplet dived through the two immiscible layers, the path of the diffused droplet exhibited a dark blue color due to its greater pH.

It was found that due to the weight of the added fiber, the drop began to form an inverted mushroom. Then, the weight continues to pull the droplet to the bottom of the container where the fiber-enhanced liquid rotates in a circular path. A portion of fiber remains latched onto the oil layer, which sustains the diffusing fiber stretching into a single, straight line filament. Yet, over time the straight filament began to buckle and bend. Over time, the droplet became increasingly unstable prior returning to a single filament once more. This transformation was evidenced until the deep blue faded as the pH level diffused. An additional experiment was carried out using a larger droplet. The droplet with a larger surface area reacted similarly, but passed the oil/ water interface at multiple contact points, as opposed to a sole point. Subsequently, multiple bending filaments appeared in the liquid. In time these filaments combined into a distinct, deformed, filament. After which, the continued instability of the filament broke into two segments, that with time became orderly. In the end, a pair of filaments was formed from the larger fiber-laced droplet.

The idea of controlling drug delivery has been studied from a plethora of angles, however, how a drug diffuses with the addition of fiber has not often been visualized. This visual investigation will establish the fundamental physics that is a critical first step in the ability to understand, predict and control the motion of a fiber enriched liquid droplet releasing into another liquid. It is of fundamental importance to the medical field and beyond if the addition of a fiber solution can influence medicine, or a solution, to reach a particular location.

Further research on this topic would involve the effect of fluid viscosity and surface tension to improve drug delivery.
Dynamics of Thin Liquid Bilayers Subjected to an External Electric Field
Authors: Nazaripoor Hadi , Koch Charles R. , Bhattacharjee Subir
Published: June 2016

Spatiotemporal evolution of liquid-liquid interface leading to dewetting and pattern formation is investigated for thin liquid bilayeres subjected to the long range electrostatic force and the short range van der Waals forces. Based on the 2D weakly non-linear thin film equation three dimensional structure evolution is numerically simulated. A combined finite difference for the spatial dimensions and an adaptive time step ODE solver is used to solve the governing equation. For initially non-wetting surfaces, the stabilizing effects of viscosity and interfacial tension and the destabilizing effect of the Hamaker constant are investigated. Electrostatic interaction is calculated analytically for both perfect dielectric-perfect dielectric and ionic conductive-perfect dielectric bilayers. Ionic conductive-perfect dielectric bilayers based on the electric permittivity ratio of layers are found to be stabilized or deformed in response to the applied external electric field.
Computational Modeling and Simulations of Isothermal Plane (Linear) Air Jet Velocity Profile for Slot Diffusers
Authors: Law Deify , Valdez Agustin
Published: June 2016

In the present work, computational modeling and simulations of isothermal plane (linear) air jet velocity profile for slot diffusers are performed. Plane air jets are formed by linear slots or rectangular openings with a large aspect ratio. Numerical simulations are performed using the commercial computational fluid dynamics (CFD) code ANSYS FLUENT. Three plane air jet flow simulations will be investigated such as free plane (linear) jets, attached jets, and air flow through a slot diffuser in a room setting. The purpose of simulating the free plane jet through a slot diffuser is to study the behavior of jet velocity profile that is not blocked by side walls or ceilings. The jet velocity profile is modified when obstructed by the walls and the air jet desires to attach to the surfaces along its path. For this reason, attached jet simulations through a slot diffuser will be conducted. The CFD study of plane air jet flows will eventually be extended to jet flows through a slot diffuser to a room to investigate the fluid flow behavior that enters a room under a ceiling. In addition, effects of two-equation turbulence models such as standard, renormalization group (RNG), and realizable k-ε on the CFD simulations will be investigated. Predicted velocity profiles and decays of free plane jet through a slot diffuser will be validated with a semi-empirical model [1]. Predicted velocity profiles of attached jet simulations will also be compared with a semi-empirical expression [2]. The slot diffuser air flow simulations will be compared with experimental data by the work of Chen and Srebric [3]. All simulations will be conducted at a specified inlet air velocity. The effects of grid resolution are also examined. It is established that the standard k-ε turbulence model best simulates attached and free jet flows. The standard k-ε turbulence model is applied to a room setting under isothermal conditions. The results are compared with non-isothermal experimental data [3]. It is shown that temperature which is a passive scalar has less influence on the flow pattern at a high air velocity than at a low air velocity in a room setting.
Numerical Investigation of Vortex Shedding in a Square Cylinder Using RANS and LES Model
Authors: Hossain Mohammad A. , Hossain Sarzina , Soiket Mohammad Ikthair Hossain
Published: June 2016

This work deals with the numerical investigation of vortex shedding in a square cylinder. The simulation has been done for 2D turbulent flow. Reynolds number (Re) is considered 22000. In order to resolve the flow field, both Reynolds Average Navier-stokes (RANS) model and Large Eddy Simulation (LES) technique were used. Standard k-epsilon model is considered among different RANS model in order to resolve the mean velocity field and the LES is used to capture the flow separation in the flow field. Both average velocity and velocity fluctuation are determined and compared. Different turbulence properties such as turbulent kinetic energy, turbulent intensity, eddy viscosity and vorticity magnitude are determined and presented for different downstream location to describe the complex flow property in turbulent regime. First the mesh independence test is done by different mesh size. ANSYS Fluent is used for the simulation. A pressured based solver is used with SIMPLE solution scheme, in order to find different flow variables. The results are compared with available published data. There are significant agreements with the experimental data.
Theoretical and Experimental Study of Hydrocyclone Performance and Equivalent Settling Area
Authors: Sabbagh Reza , Lipsett Michael G. , Koch Charles R. , Nobes David S.
Published: June 2016

Predicting the performance of a solid-liquid separation process can help in comparing different separators for selection and design. This can be applied to hydrocyclone technology which is used widely in industry due to being an inexpensive device that is easy to operate and maintain and which has no moving parts. Environmental concerns and technological issues in separation processes are motivating the design of higher efficiency systems with less capital and operating costs. There is a need therefore for, methods to compare different separation technologies.

In spite of extensive research into hydrocyclone performance, a mathematical model that can predict the performance of a hydrocyclone for comparison with other centrifugal separators is rare in the literature. The main objective of this research is to apply theoretical and experimental approaches to study hydrocyclone performance in order to propose an applicable separation performance model that represents the whole hydrocyclone operating range. A mathematical model is developed to explore the performance of the separator and to predict the hydrocyclone’s equivalent area as compared to a continuous gravity settling tank. A performance chart that can be used for selection and design of hydrocyclones is the result of the model.
Wake Alleviating Devices for Offshore Wind Turbines
Authors: Klimchenko Vera
Published: June 2016

The wake behind an offshore wind turbine can persist for several turbine diameters, so decreasing the space between wind turbines in an array leads to strong wake-turbine interactions and a decrease in efficiency of the wind turbines downstream. The dominant structures in the wake of a horizontal axis wind turbine are large helical tip vortices. Implementing devices on the blade tips of a wind turbine can induce mixing into the tip vortex core, encouraging breakup of the tip vortices and wake dissipation. A wake that dissipated more quickly can maximize the farm-level efficiency by allowing more turbines to be installed in a fixed area.

This study focuses on quantifying the effectiveness of three different blade-mounted devices in speeding up the dissipation of the wake of an offshore horizontal axis wind turbine. Experiments were conducted in a low speed, low turbulence wind tunnel. A small scale wind turbine model was designed using optimum rotor theory to match the tip speed ratio of an offshore wind turbine. The baseline case consisted of a wind turbine rotor without blade-mounted devices. It was tested in the wind tunnel under a range of free stream conditions, and the rotational speed was measured to determine the operational tip speed ratios. A second test case was the same rotor, but with winglets at the blade tips designed to weaken the tip vortices. A third test case was the baseline case rotor with serrated blade tips, designed to introduce turbulence into the core of the tip vortex. Smoke flow visualization and particle image velocimetry (PIV) were used to observe the dissipation of the turbines’ wake. The effectiveness of the blade-mounted devices on wake dissipation was evaluated with a special interest in optimizing the overall energy harvested by an offshore wind farm of a fixed area. It was shown that both tip treatments tested have the capacity to reenergize the flow and decrease the momentum deficit in the wake of a wind turbine.
LBM Simulation of Electro-Osmotic Flow (EOF) in Nano/Micro Scales Porous Media With an Inclusive Parameters Study
Authors: Zakeri Ramin , Lee Eon Soo , Salimi Mohammad Reza
Published: June 2016

In this paper, we present our results about simulation of 2D-EOF in Nano/Micro scales porous media using lattice Boltzmann method (LBM) in micro-channel for EOF. The high efficient numerical code use strongly high nonlinear Poisson Boltzmann equation to predicate behavior of EOF in complex geometry. The results are developed with precisely investigation of several effective parameters on permeability of EOF, such as geometry (channel height and number and location of charge), external electric field, thickness of Debye length (ionic concentration), and zeta potential. Our results are in excellent agreement with available analytical results. Our results show that for certain external electric field, zeta potential and porosity, there is an optimal Kh parameter (ionic concentration and channel height in this study) for velocity profiles. Based on the current study, homogenous zeta potential distribution on solid porous media, zeta potential and thickness of Debye length (Kh parameter) can dramatically affect on EOF permeability linearly or non-linearly, depend on amount of quantities. Thus, different arrangements are also considered. We show that prediction of EOF behavior in complex geometry with regarding role of effective parameters is completely possible for various applicable conditions.
Simulation of Nano Polymer Chain Sensor in Electroosmotic Flow Using Dissipative Particle Dynamics (DPD) Method
Authors: Zakeri Ramin , Lee Eon Soo
Published: June 2016

In this paper, we simulate the inflation of fixed two ends polymer chain curvature as nano sensor in EOF which it provides a porous media for DPD (dissipative particles dynamics) solvent particles and inflation is resulted. Particles are driven by electroosmotic flow in nanochannel which is as an external force in DPD algorithm and part of particles should move through a non-charged polymer chain which they affect on curvature of polymer chain. Our results for simple nanochannel in EOF are validated with analytical results and we have developed our results when a fixed two ends polymer chain subject in nanochannel as nano sensor in both cases including simple and stenosis nanochannel. Amount of inflation (displacement) of fixed two ends polymer chain is related to electroosmotic forces and interaction between particles. Our aim is that a relation between effective parameters in electroosmotic flow such as electric field, zeta potential, kh parameters and amount of inflation in polymer chain curvature (interaction between particles) is provided for each test case. Based on our results, there is a linear relation between some parameters such as external electrical field, zeta potential and kh parameters (effect of Debye length and channel height) in low electrosmotic forces but non-linear behavior is observed for high electroosmotic forces especially for stenosis channel case. This study opens some new way toward designing proper nano EOF sensors to measure flow characteristics in EOF applications.
Study of the Effect of Tangential Point Blowing on the Incompressible Boundary Layer Flow Around a Circular Cylinder
Authors: Ghosh S. K. , Mukherjea S. K. , Datta B. N.
Published: June 2016

In the present work, two dimensional flow simulations have been performed to study the effect of tangential blowing on the drag force for the case of flow around a circular cylinder only at Reynolds number (Re) 200. Blowing ports have been placed symmetrically with respect to the horizontal flow axis. The effect of blowing on the boundary layer has been studied with respect to the intensity of blowing as well as port position of blowing. For a particular intensity of blowing, oscillations of the front stagnation point and the separation point was studied. It was found that oscillation frequencies were identical with that of lift coefficient. It was also observed that with the increase of the intensity of the blowing the position of the separation point shifts downstream (separation delay)thus the wake becomes narrower resulting the decrease of drag. Strouhal number was found to increase with the intensity of blowing. It was observed that the Strouhal number as well as the position of the separation point is influenced by the position of the blowing port. Although, for a significant range of the blowing port positions the Strouhal number is observed to be constant. Drag was found to be influenced by the position of the blowing ports. Pressure drag was found to be more significant. Thus total drag is influenced primarily by the pressure drag. It was observed that in the range of 40° to about 110° for the position of the blowing port drag decreased. But beyond 110° it increased again.
Development of Water Treatment Systems Using Interaction of Pressure Waves, Cavitation Bubbles and Micro Bubbles
Authors: Tamagawa Masaaki
Published: June 2016

This paper describes the fundamental investigations for developing new water treatment system using cavitation bubbles, micro bubbles and pressure waves (shock waves). To understand the fundamental phenomena of interaction of these factors, the pressure using cavitation bubbles and micro bubbles was measured, and the influence of micro bubble on the cavitation water treatment system was investigated. From these results, it was concluded that (1) there are two types of bursting pressure histories when pressure waves and cavitation bubble are working on micro-bubble, (2) frequency of bursting pressure from micro bubble and cavitation bubbles was increased by increasing working pressure, (3) the efficiency of water treatment was increased by increasing cavitation bubbles, (4) the improved water treatment system was proposed by changing the seeding position of the micro bubbles.
Numerical Simulation of Solid-Phase Split at Junctions in Particle Laden Pipe Flow
Authors: Kharoua N. , AlShehhi M. , Khezzar L.
Published: June 2016

The present study is a part of an industrial research project and consists in simulating a gas-particle flow through junctions under different geometrical and flow conditions. The purpose is to study the effects of the size of particles, the angles of the junction and the flow rate on the flow split. The particles are usually considered as products to transport, such as in pneumatic conveying, where phase split, if necessary, is done in symmetrical Y-junctions to avoid mal-distribution issues. Thus, asymmetrical junctions were, usually, avoided in transportation networks. However, it appeared that the particles can manifest within networks for transportation of gases as contaminants to be eliminated. A typical example is that of Black Powder in gas pipelines in the oil industry. In such piping networks, different types of junctions can be used and it is worth understanding the behavior of particles for unsymmetrical configurations as well. The numerical simulation combines the k-ε and the Discrete Phase DPM turbulence and multiphase models, respectively. Relatively, good agreement in the results between the model and the experiments was obtained. The simulations were extended to Black Powder particles and the corresponding results showed interesting features for different Stokes numbers. The simulation results showed that, for Stokes numbers much smaller than unity (St≤0.2), the solids phase split can be considered to follow the air flow split closely. For intermediate Stokes numbers (St≈1), the particles gain some independence from the gaseous phase. For Stokes numbers slightly higher than unity (St≥5), the orientation plays an important role.
Aggregation and Effective Thermal Conductivity of Nanofluids: Dependence on Cluster Size and Morphology
Authors: Reyes-Mata Miguel , Blawzdziewicz Jerzy , Wajnryb Eligiusz , Zurita-Gotor Mauricio
Published: June 2016

We combine a multipolar expansion technique and a cluster-cluster aggregation algorithm to accurately compute the effect of aggregation on the thermal conductivity of nanofluids. Results show that the normalized enhancement in the effective conductivity of nanofluids exhibits a power law dependence on average cluster size. The exponent in the power law is a decreasing function of the fractal dimension, and is always larger than zero, thus predicting enhancements in excess of Maxwell’s theory for well dispersed individual nanoparticles. Results are interpreted in terms of an effective particle size for heat conduction of aggregates which approximately scales as the gyration radius, specially at larger fractal dimensions.
Separated Turbulent Boundary Layer Under Unsteady Adverse Pressure Gradients: DNS and RANS
Authors: Park Junshin
Published: June 2016

Predicitve capabilities of Reynolds Averaged Navier-Stokes (RANS) techniques have been assessed using SST k–ω model and Spalart-Allmaras model by comparing its results with direct numerical simulation (DNS) results. It has been shown that Spalart-Allmaras and SST k–ω model predict an earlier separation point and a bigger recirculation bubble as compared to the DNS result. Velocity profiles predicted by RANS for both models closely match with DNS results for the steady adverse pressure gradient case. However, the RANS fail to predict correct velocity profiles for unsteady adverse pressure gradients not only for inside the bubble but also after the reattachment zone. To provide the backgrounds for improving RANS models, these differences are explained with Reynolds stress and eddy viscosity which differ between the steady and unsteady adverse pressure gradient RANS cases.
Computational Study of Savonius Wind Turbines
Authors: Rashidi Majid , Kadambi Jaikrishnan R. , Chinchore Asmita
Published: June 2016

This work presents a computational study of a two-blade and a three-blade Savonius vertical axis wind turbines. The two-blade turbine was considered to be oriented at 0, 45, 90, and 135 degrees in reference to the direction of the prevailing wind. For the three-blade turbine, the orientations taken into account were 0, 30, 60, and 90 degrees in reference to the direction of the prevailing wind. The basic aim of this work was to study how the two designs are different from each other in terms of the forces acting on their blades. The computational simulations considered the turbines to be subjected to constant wind velocities of 5, 10, 20, and 30 m/s. Computational Fluid Dynamics (CFD) analyses were conducted for every case to find out the forces acting on the turbine blades for each orientation. All cases were run using “transition-SST” flow model and the turbine blades were meshed using ‘Quadrilateral Pave’ meshing scheme. Maximum change in pressure on the turbine blade occurs when the two-blade turbine is perpendicular to direction of the prevailing wind, i.e. at 90 degree. On the other hand, when three-blade turbine is at 60 degree orientation, maximum change is pressure occurs on the turbine blade. For the dimensions selected in this study (each blade having a radius of 0.3 m and height of 0.6 m) the maximum net forces on the two-blade turbine was calculated to be 298 N, while this value was 210 N on the three-blade turbine.
Analysis of the Process-Structure-Behavior Interaction in Bio-Sourced Polymers: Role of the Crystallization Kinetics
Authors: Boutaous Mhamed , Refaa Zakariaa , Zinet Matthieu , Xin Shihe , Bourgin Patrick
Published: June 2016

PLA (Poly Lactic Acid) is a bio-sourced and biodegradable polymer. It represents an alternative for polymers issued from petrochemical synthesis. Unfortunately, the crystallization kinetics of PLA is very slow and limits the possibility to extend its application in several industrials domains. The enhancement of the PLA crystallization kinetic can be obtained by addition of nucleating agents of by ordering the molecular chains during flow, as in processing conditions. During processing of thermoplastic polymer experiences several thermomechanical conditions influencing drastically its final properties and mechanical behavior. During injection molding process, macromolecules are oriented and ordered due to the shear and elongation imposed by the melt flow in the mold during the filling step. As a consequence, supplementary nucleation is created in the polymer, leading to the acceleration of the crystallization kinetics. In this work, we propose to analyze and to quantify the role of the flow, the temperature kinetics and the nucleating agent on injected PLA parts structure and their mechanical behavior. A parametric analysis of the relationship between the polymer, its structure and the processing condition will be presented. The competition (sometimes antagonism) between several parameters, as the shear rate, the temperature kinetics and the nucleating agent will be highlighted.
Experimental Measurements and Flow Visualization of Water Cavitation Through a Nozzle
Authors: Wilms Jeffrey , Beck Terry , Sorensen Christopher M. , Hosni Mohammad H. , Eckels Steven J. , Tomasi Don
Published: June 2016

A typical refrigeration loop is composed of an evaporator, compressor, condenser, and an expansion valve. There are many possible refrigerants that can be used, but the physical properties of water make it ineffective in the traditional refrigeration loop. But if water could be used it would have many advantages as it is abundant, cheap, and is safe for the environment. As part of development of a new refrigeration loop using water, flow visualization and cavitation of water through nozzles are being investigated. Cavitation is generally defined as creating vapor from liquid, not through adding heat, but by decreasing the pressure. In a converging/ diverging nozzle as the cross sectional area is constricted the velocity of the flow will increase, decreasing the pressure. Therefore, by flowing water through the nozzle it will cavitate. Transforming liquid into gas requires a certain amount of energy, defined as the latent heat. When a liquid is turned to vapor by an increase in the temperature the latent heat is provided by the heat transfer to the system. As no energy is being added in the nozzle to cause the cavitation, the heat to create the vapor comes from the liquid, effectively causes a temperature drop.

This article presents results for the flow visualization of the water cavitating as it goes through the nozzle. Under different flow conditions and nozzle geometries the cavitation manifested itself in different formations. When gasses were entrained in the water they formed bubbles, creating a nucleation site and moving through the nozzle, called travelling bubble cavitation. In venturi nozzles the cavitation nucleated off of the wall, forming attached wall cavitation. When water flowed out of an orifice, a turbulent water jet was formed which caused vapor to form around it, causing shear cavitation. When the water was rotated prior to the throat of an orifice, the orifice jet expanded radially and formed swirl cavitation.
Development and Application of an Alternating-Color Micro-PIV System
Authors: Jaw Shenq-Yuh , Sheen Jyh-Jong , Hwang Robert
Published: June 2016

In this study, light emitted from red, green, and blue LEDs is adopted as the light source of an alternating-color micro-PIV system for micro flows measurement. The strobe frequency of the LED can easily reach 20,000Hz, which is high enough to provide the time resolution required for most micro flows measurement. A cardioid annular condenser is adopted in the micro-PIV system so that the incident light from the LED is redirected and only the light emitted from fluorescent particles reaches the object lens of the microscope. The image quality is significantly improved. Clear dark background particle images of micro flows are recorded from the proposed LED micro-PIV system. In addition, the diffraction limit of the microscope is improved from half of the wavelength to one-fifth of the wavelength. For alternating-color multiple-exposure image application, a triple-exposure alternating-color image — sequentially illuminated by red, green, and blue LED light — is recorded on a single frame by a color CCD camera. Three unique color images — a blue, a green, and a red image respectively — are obtained from separating the triple-exposure image. With three sequential images available, the velocity, acceleration distributions of micro flow, and different phases of the multiphase flow can be measured from these unique color sequential images. The alternating-color micro-PIV system is then applied to measure micro flow past a cylinder, circulation in a micro-droplet, hydrodynamic focusing sheath flow, and two-phase flow in micro channels. Satisfactory results are obtained for all the flows measured.
XPS study of thermal and electron-induced decomposition of Ni and Co acetylacetonate thin films for metal deposition
Authors: Weiss Theodor , Warneke Jonas , Zielasek Volkmar , Swiderek Petra , Bäumer Marcus
Published: June 2016

Optimizing thin metal film deposition techniques from metal-organic precursors such as atomic layer deposition, chemical vapor deposition (CVD), or electron beam-induced deposition (EBID) with the help of surface science analysis tools in ultrahigh vacuum requires a contamination-free precursor delivery technique, especially in the case of the less volatile precursors. For this purpose, the preparation of layers of undecomposed Ni(acac)2 and Co(acac)2 was tried via pulsed spray evaporation of a liquid solution of the precursors in ethanol into a flow of nitrogen on a CVD reactor. Solvent-free layers of intact precursor molecules were obtained when the substrate was held at a temperature of 115 °C. A qualitative comparison of thermally initiated and electron-induced precursor decomposition and metal center reduction was carried out. All deposited films were analyzed with respect to chemical composition quasi in situ by x-ray photoelectron spectroscopy. Thermally initiated decomposition yielded higher metal-to-metal oxide ratios in the deposit than the electron-induced process for which ratios of 60:40 and 20:80 were achieved for Ni and Co, resp. Compared to continuous EBID processes, all deposits showed low levels of carbon impurities of ∼10 at. %. Therefore, postdeposition irradiation of metal acetylacetonate layers by a focused electron beam and subsequent removal of intact precursor by dissolution in ethanol or by heating is proposed as electron beam lithography technique on the laboratory scale for the production of the metal nanostructures.
Super Bowl Team Tones: Analyzing Patriots and Seahawks Blogospheres
Authors: Mendenhall Douglas L.
Published: June 2016

In an introductory undergraduate media course, Super Bowl XLIX was used as a hands-on vehicle to introduce students to the discipline of mass-media research. From a week before and after Super Bowl XLIX, 269 original blog posts and 91 sets of appended comments from Web sites devoted to the Seattle Seahawks and New England Patriots were analyzed for significant differences using Diction 7.0, a common word-counting program that measures tone in dozens of ways. More than a dozen variations found in the blog messages are used to describe a “team tone” unique to Seahawks blogs and another unique to Patriots blogs. Some elements of these team tones are present across all messages, while others existed only before the game was played or arose only after New England’s dramatic win in the closing moments. Postgame variations include greater optimism in the tone of New England Patriots bloggers and greater hardship and denial in the tone of Seattle Seahawks bloggers. Results are discussed from the perspective of social-identity theory.
MET signaling in keratinocytes activates EGFR and initiates squamous carcinogenesis
Authors: Cataisson Christophe , Michalowski Aleksandra M. , Shibuya Kelly , Ryscavage Andrew , Klosterman Mary , Wright Lisa , Dubois Wendy , Liu Fan , Zhuang Anne , Rodrigues Kameron B. , Hoover Shelley , Dwyer Jennifer , Simpson Mark R. , Merlino Glenn , Yuspa Stuart H.
Published: June 2016

The receptor tyrosine kinase MET and oncogenic RAS both stimulate EGFR signaling to initiate skin cancer.
Summary and Recommendations from the National Institute of Allergy and Infectious Diseases (NIAID) Workshop “Gonorrhea Vaccines: the Way Forward”
Authors: Wetzler Lee M. , Feavers Ian M. , Gray-Owen Scott D. , Jerse Ann E. , Rice Peter A. , Deal Carolyn D.
Published: June 2016

There is an urgent need for the development of an antigonococcal vaccine due to the increasing drug resistance found in this pathogen. The U.S. Centers for Disease Control (CDC) have identified multidrug-resistant gonococci (GC) as among 3 “urgent” hazard-level threats to the U.S. population. In light of this, on 29 to 30 June 2015, the National Institute for Allergy and Infectious Diseases (NIAID) sponsored a workshop entitled “Gonorrhea Vaccines: the Way Forward.” The goal of the workshop was to gather leaders in the field to discuss several key questions on the current status of gonorrhea vaccine research and the path forward to a licensed gonorrhea vaccine. Representatives from academia, industry, U.S. Government agencies, and a state health department were in attendance. This review summarizes each of the 4 scientific sessions and a series of 4 breakout sessions that occurred during the one and a half days of the workshop. Topics raised as high priority for future development included (i) reinvigoration of basic research to understand gonococcal infection and immunity to allow intervention in processes essential for infection; (ii) clinical infection studies to establish parallels and distinctions between
in vitro
and animal infection models versus natural human genital and pharyngeal infection and to inform
in silico
modeling of vaccine impact; and (iii) development of an integrated pipeline for preclinical and early clinical evaluation and direct comparisons of potential vaccine antigens and adjuvants and routes of delivery.
Live Attenuated Borrelia burgdorferi Targeted Mutants in an Infectious Strain Background Protect Mice from Challenge Infection
Authors: Hahn Beth L. , Padmore Lavinia J. , Ristow Laura C. , Curtis Michael W. , Coburn Jenifer
Published: June 2016

Borrelia burgdorferi
,
B. garinii
, and
B. afzelii
are all agents of Lyme disease in different geographic locations. If left untreated, Lyme disease can cause significant and long-term morbidity, which may continue after appropriate antibiotic therapy has been administered and live bacteria are no longer detectable. The increasing incidence and geographic spread of Lyme disease are renewing interest in the vaccination of at-risk populations. We took the approach of vaccinating mice with two targeted mutant strains of
B. burgdorferi
that, unlike the parental strain, are avirulent in mice. Mice vaccinated with both strains were protected against a challenge with the parental strain and a heterologous
B. burgdorferi
strain by either needle inoculation or tick bite. In ticks, the homologous strain was eliminated but the heterologous strain was not, suggesting that the vaccines generated a response to antigens that are produced by the bacteria both early in mammalian infection and in the tick. Partial protection against
B. garinii
infection was also conferred. Protection was antibody mediated, and reactivity to a variety of proteins was observed. These experiments suggest that live attenuated
B. burgdorferi
strains may be informative regarding the identification of protective antigens produced by the bacteria and recognized by the mouse immune system
in vivo
. Further work may illuminate new candidates that are effective and safe for the development of Lyme disease vaccines.
Study protocol for a pilot, randomised, double-blinded, placebo controlled trial of perineural local anaesthetics and steroids for chronic post-traumatic neuropathic pain in the ankle and foot: the PREPLANS study
Authors: Bhatia Anuj , Bril Vera , Brull Richard T , Perruccio Anthony , Wijeysundera Duminda , Alvi Sabbeh , Lau Johnny , Gandhi Rajiv , Mahomed Nizar , Davis Aileen M
Published: June 2016

Introduction

Peripheral neuropathic pain (PNP) associated with trauma is often refractory to treatment. Administration of local anaesthetics (LA) and steroids around injured nerves has been proposed as an option for patients unresponsive to conventional treatments for refractory PNP following trauma. There is insufficient evidence to support a large, potentially expensive, full-scale randomised controlled trial (RCT) that involves comparison of effects of perineural steroids and LA against LA or saline injections on analgesia, physical and psychological functioning, and quality of life. There is also a lack of data that would allow estimation of analgesic efficacy or sample size for the full-scale RCT. The objective of this pilot RCT is to yield information to support planning of a full-scale RCT in this population.

Methods and Analysis

30 participants with post-traumatic PNP in the ankle and foot of moderate-to-severe intensity and duration of more than 3 months will be enrolled in this pilot RCT. Participants will be randomised to receive three ultrasound-guided perineural injections of 0.9% saline, 0.25% bupivacaine (a long-acting LA) or a combination of 0.25% bupivacaine and a steroid (methylprednisolone 16 mg per nerve) at weekly intervals. The primary objectives are to determine the feasibility and sample size of a full-scale RCT in this population. The secondary objectives are to evaluate the effect of study interventions on analgesia, persistence of neuropathic pain, psychological and physical function, quality of life and participants' global impression of change at 1 and 3 months after the interventions. In addition, adverse effects associated with perineural injections and with systemic absorption of steroids will also be recorded.

Ethics and Dissemination

The protocol was approved by the University Health Network Research Ethics Board (UHN REB number 15-9584-A). The results will be disseminated in peer-reviewed journals and at scientific conferences.

Trial registration number

NCT02680548; Pre-results.
Developing psychological services following facial trauma
Authors: Choudhury-Peters Deba , Dain Vicky
Published: June 2016

Adults presenting to oral and maxillofacial surgery services are at high risk of psychological morbidity. Research by the Institute of Psychotrauma and the centre for oral and maxillofacial surgery trauma clinic at the Royal London hospital (2015) demonstrated nearly 40% of patients met diagnostic criteria for either depression, post traumatic stress disorder (PTSD), anxiety, alcohol misuse, or substance misuse, or were presenting with facial appearance distress. Most facial injury patients were not receiving mental health assessment or treatment, and the maxillofacial team did not have direct access to psychological services. Based on these research findings, an innovative one-year pilot psychology service was designed and implemented within the facial trauma clinic.

The project addressed this need by offering collaborative medical and psychological care for all facial injury patients. The project provided brief screening, assessment, and early psychological intervention. The medical team were trained to better recognise and respond to psychological distress.