bluuebunny/crossref_metadata_2025_split huggingface dataset:
CFD Analysis of the Bifurcation Based on a Precision Modeling System
Authors: Kimura Y. , Yamaguchi T. 
Published: November 2021

Abstract
The purpose of this study was to investigate the relationship between blood flow and atherosclerosis using Computational Fluid Dynamics. Atherosclerosis is suspected to be related to blood flow, since it develops at specific points on vessel walls. Among these specific locations, bifurcations of blood vessels are especially prone to atherosclerosis, particularly the lateral walls of the common iliac arteries1. This distribution of lesions is believed to depend on fluid dynamics phenomena, particularly the wall shear stress. Due to the complex geometry of a real artery, the fine flow structure in an arterial bifurcation may be too complex to study using in vivo or in vitro experiments. Therefore, CFD is one of the most powerful ways to investigate flow in an arterial bifurcation. However, the relevant CFD model must be constructed to obtain a reliable computational analysis. In general, a bifurcation has a complex 3-D configuration, particularly at its sharp edge. Any minute deformation or relative displacement of the bifurcation is thought to have a significant effect on blood flow. In this study, a histology technique, in which the embedded vessels are sliced into thickness of the order of 1 micrometer, was used to model the arterial bifurcation. A computer was used to capture 2-D images of the face of the specimen block after each slice was removed. Then, serial images were used to reconstruct the 3-D blood vessel configuration with a precision appropriate for CFD analysis.
Effects of Hydrostatic Loading Amplitude and Frequency on Rabbit Disc Nucleus Cells
Authors: Kasra Mehran , Goel Vijay , Martin James , Wang Shea-Tien , Choi Woosung , Buckwalter Joseph 
Published: November 2021

Abstract
Long-term occupational exposure to whole-body vibration increases the risk of disc degeneration and the consequent back pain [1]. The pathogenesis of vibration induced disorders is still not completely clear and there is no effective treatment. Although the potential effects of vibrational stress on extracellular matrix (ECM) assembly and degradation are particularly relevant to the clinical findings of the vibration induced disorders, the effects of vibrational loads on disc cells are largely unknown. It has been shown that hydrostatic pressure directly affects the synthesis of collagen and proteoglycan by the intervertebral disc cells [2–5]. However, these studies investigated only the extent of the effect of quasi-static hydrostatic loads. During daily occupational activities intervertebral disc is exposed to dynamic oscillatory hydrostatic loads, characterized by wide frequency spectrum and variable amplitude. In this case, a physiologic level of amplitude and frequency of hydrostatic pressure may be essential for maintaining the matrix of the disc, while an abnormal amplitude and frequency of hydrostatic pressure may accelerate disc degeneration. The ranges of good and bad loading frequencies and amplitudes still need to be discovered. The objective of this study was to find which of loading frequency and loading amplitude has more influence in affecting disc cell response to vibration. To address this issue we developed a mechanically-active culture system capable of delivering a wide range of loading frequency and amplitude of hydrostatic pressure to cultures of nucleus pulposus cells. We used nucleus cells, which are exposed mainly to hydrostatic loading in vivo.
A Novel Device for Direct Permeation Measurements of Hydrogels and Soft Hydrated Tissues
Authors: Andarawis Nelly A. , Seyhan Sara L. , Mauck Robert L. , Soltz Michael A. , Ateshian Gerard A. , Hung Clark T. 
Published: November 2021

Abstract
The goal of this study was to develop a system to reliably measure the intrinsic hydraulic permeability of hydrogels and soft hydrated tissues. Such a device can be used to assess the development of functional properties in tissue engineered constructs [1]. The design parameters for such a device include ease of assembly and the ability to measure hydraulic permeability over a range of specimen deformations. To meet these criteria, a device was designed that could quantify the hydraulic permeability of a sample under different levels of deformation, allowing characterization of strain-dependent effects. The device was tested on both agarose and articular cartilage specimens, yielding permeability values consistent with published data [2]. The intrinsic hydraulic permeability of a tissue is an important parameter that governs fluid exudation during deformational loading. The ability of articular cartilage, which exhibits non-linear strain dependent hydraulic permeability [3], to generate and sustain interstitial fluid pressurization is essential to its functional properties (e.g., load bearing and lubrication). This novel device allows for direct and reliable measurement of these physical properties.
Feasibility of Using an Active Actuator for Two-Dimensional Vibration Abatement in a Turning Process
Authors: Yan W. Y. , Al-Jumaily A. M. 
Published: November 2021

Abstract
A simulation model that considers the radial and tangential vibrations and their abatement using active actuators in a turning process is developed. The model is simulated using Simulink in Matlab environment to assess the possibility of using an active actuator to reduce vibrations in two directions. Comparison is made between the two orthogonal actuators scenario and the one inclined actuator scenario. The results indicate that vibrations reduction using an active inclined actuator is comparable to that of two orthogonal ones.
A Multi-Mode Approach for the Nonlinear Vibrations of Circular Cylindrical Shells
Authors: Pellicano Francesco , Amabili Marco , Païdoussis Michael P. 
Published: November 2021

Abstract
The nonlinear vibrations of simply supported, circular cylindrical shells, having geometric nonlinearities is analyzed. Donnell’s nonlinear shallow-shell theory is used, and the partial differential equations are spatially discretized by means of the Galerkin procedure, using a large number of degrees of freedom. A symbolic manipulation code is developed for the discretization, allowing an unlimited number of modes. In the displacement expansion particular care is given to the comparison functions in order to reduce as much as possible the dimension of the dynamical system, without losing accuracy. Both driven and companion modes are included, allowing for traveling-wave response of the shell. The fundamental role of the axisymmetric modes, which are included in the expansion, is confirmed and a convergence analysis is performed. The effect of the geometric shell characteristics, radius, length and thickness, on the nonlinear behavior is analyzed.
Estimation of Chaotic Parameter Regimes via Generalized Competitive Modes Approach
Authors: Yao Weiguang , Yu Pei , Essex Chris 
Published: November 2021

Abstract
A procedure is proposed to estimate the parameter regimes of chaos in nonlinear systems by implementing a mathematical version of mode competition. The idea is that for a system to be chaotic there must exist at least two generalized competitive modes in the system. The Lorenz system and a thin plate in flow-induced vibrations system are analyzed to find chaotic regimes by this procedure.
On a Chaos Control for the Logistic Map
Authors: Wang Xiaohua , Jing Zhongliang , Luo Albert C. J. 
Published: November 2021

Abstract
A method for chaos control based on the feedback control principle is presented. The chaotic behavior of logistic map for μ = 4 is discussed as a simple problem. Comparison of control performance between two different control methods is given. The simulation results show that the presented control method for chaos gives a better performance than the inverse system method.
Direct Perturbation Analysis on Transmission Lines With Detuning Pendulums
Authors: Pan Kelin , Yu Pei 
Published: November 2021

Abstract
A general model of cable dynamics is used to analyze the vibration of transmission lines equipped with the control device – detuning pendulums. The model considers complex loading, including nonlinear aerodynamic force and concentrated load. An early developed perturbation method, called direct perturbation method (DPM), is applied to study cable motion. This approach does not need to transform the original partial differential equation to an ordinary differential equation, and the solution procedure is systematic. Steady-state solutions and stability conditions are briefly discussed.
Asymmetrically Respiratory System Simulation for Identifying Airway Occlusion
Authors: Al-Jumaily A. M. , Al-Fakhri Y. 
Published: November 2021

Abstract
A theoretical model is developed to investigate the dynamic characteristic of a healthy and an occluded asymmetric respiratory system. The model takes the elastance and inertance of the airway walls into consideration. Frequency spectra of the input impedance determined at the throat are generated and examined for two regimes of airway terminations and for occlusion at each generation from the end terminal (alveolar sacs) up to the proximal end of the trachea. In the asymmetric arrangement the impact of merging dissimilar flows due to different airways geometry from the adjacent regions is considered. Further, the effect of the nature of the terminal impedance (ie. rigid termination or compliant termination) on the acoustic response is also investigated.
Air Velocity Regulation in a Wind Tunnel
Authors: Ebrahimi M. , Whalley R. 
Published: November 2021

Abstract
A wind tunnel model, relating fan motor speed and ventilator opening to the air velocity in the tunnel casing and working section, is presented. Regulation, using the naturally occurring outputs such that accurate adjustments in the air velocity at the working section, with prescribed transient, gusting conditions is required. Confined steady state interaction together with minimum control effort expenditure is essential. A simple feedback configuration with passive network compensation is proposed, satisfying these performance requirements thereby.
Electro-Hydraulic Camless Valvetrain System Modeling
Authors: Asgari J. , Hrovat D. 
Published: November 2021

Abstract
This report describes a development of Matrixx model of prototype Electro-hydraulic Camless Valvetrain (ECV). The model was developed using bond graph techniques and was partially validated with respect to limited available experimental data for a single-cylinder laboratory implementation. The report also discusses system sensitivity and other issues which characterize this in practice highly challenging concept.
Natural Convection Heat Transfer and Flow Pattern in an Inclined Arc-Shape Enclosure
Authors: Chen Chin-Lung , Cheng Chin-Hsiang 
Published: November 2021

Abstract
Numerical and experimental investigations have been conducted to study the flow and heat transfer characteristics for the buoyancy-induced flow inside an inclined arc-shape enclosure. Mathematical model in form of a stream function-vorticity formulation representing the laws of conservation in mass, momentum, and energy is expressed in a curvilinear coordinate frame and solved by a finite-volume discretization method. Heat transfer and flow pattern are predicted at various Grashof numbers and inclination angles. Meanwhile, an experimental system is developed and a flow-visualization technique using smoke is employed to observe the flow pattern. Results show that when the Grashof number is higher than 105, the increase in natural convection heat transfer becomes appreciable. The vortex strength and pattern are found to be greatly dependent on the inclination angle. The range of the Grashof number considered in this study is up to 107 and the inclination angle is varied from 0 to π.
Pressure Effects on the Buoyancy-Induced Convective Heat Transfer for Non-Boussinesq Fluid in a Rectangular Enclosure
Authors: Hung Kuo-Shu , Cheng Chin-Hsiang 
Published: November 2021

Abstract
Numerical predictions of pressure effects on natural convective heat transfer characteristics for a non-Boussinesq fluid in a rectangular enclosure are presented. The solution method is developed based on a compressible flow model and is employed to simultaneously determine the absolute pressure, density, temperature, and velocity distributions in the enclosure. Discretization equations are derived from the integral mass, momentum, and energy equations on a staggered grid. The fluid pressure in the enclosure is varied from 20 to 300 kPa such that the flow behavior in a vacuum or pressurized system can be observed. Physical situations investigated also include cases in a wide range of wall temperature difference associated with various length scales, corresponding to an equivalent modified Rayleigh number ranging from 104 to 106. The validity of the incompressible flow model coupled with the Boussinesq approximation for the fluid density, which is commonly used in the existing studies of the buoyant flows, is discussed.
A Numerical Study of Natural Convective Flow in a Narrow Open Top Enclosure With a Linearly Varying Side-Wall Temperature Attached to a Large Square Enclosure
Authors: Oosthuizen Patrick H. , Scott David 
Published: November 2021

Abstract
Natural convective flew in a large square enclosure with a narrow rectangular enclosure mounted symmetrically on the upper surface of this main enclosure has been considered. The horizontal bottom and vertical side-walls of the main enclosure are assumed to be at a uniform high temperature and the vertical side-walls of the narrow top enclosure are assumed have a temperature that varies linearly with height above the main enclosure. The top horizontal wall of the upper enclosure is assumed to be adiabatic The situation consider is an approximate model of that which arises when measurements have to be made in a large enclosure containing a hot fluid and in which the measuring instrument is mounted in a small enclosure which is open at one end to the main tank and which has the instrument mounted at the opposite closed end. In order to ensure that the instrument is not exposed to a temperature that is above its operational limit, the walls of this small enclosure are cooled. Fluid properties have been assumed constant except for the density change with temperature that gives rise to the buoyancy forces, this being treated by means of the Boussinesq type approximation. The governing equations have been written in dimensionless form and the resultant dimensionless equations have been solved using a finite-element method. Results have been obtained for a Prandtl number of 0.7. The effects of Rayleigh number and dimensionless height and width of the top enclosure on the maximum temperature of the top adiabatic surface have been investigated. The results show that provided the aspect ratio of the upper enclosure is kept large, overheating of the upper adiabatic surface of the top enclosure is not likely to occur.
A New Type Two-Layer Turbulence Model for Natural Convection Applied to a Diffrentially Heated Channel
Authors: Hammami T. , Bennacer R. , Mohamad A. A. 
Published: November 2021

Abstract
The near wall region poses numerical difficulties and current modellings are either expensive or lack universality. Using the recent DNS done on natural convection flow in an infinite channel differentially heated for (104 &lt; Ra &lt; 106) a scaling analysis is developed and a one-equation near-wall turbulence model is deduced. The model coupled with a Low Reynolds Number Model (LRN) in the outer region was applied to calculate natural flow for different Ra numbers. It yields good performance, computation time reduction and much better heat transfer prediction compared to the diffusive Jones Launder LRN model.
Resolution Requirements for DNS of Turbulent Heat Transfer Near the Heated Wall at Prandtl Number 5.4
Authors: Bergant Robert , Tiselj Iztok , Hetsroni Gad 
Published: November 2021

Abstract
Theoretically, the grid spacing for Direct Numerical Simulations of heat transfer at Prandtl numbers higher than one should be inversely proportional to the square root of Prandtl number (Tennekes, H., Lumley, J.L [1]). The grid refinement study of Na and Hanratty (2000) [2] at Pr = 10 showed that finer grid is not required in streamwise and spanwise directions, but is necessary in the wall-normal direction.
In the present work three different DNS studies were performed with different resolutions at Pr = 5.4 and friction Reynolds number Re = 171.
The first DNS was performed using the resolution, which is known to be sufficient for the velocity field simulation, the second simulation was performed with the refined grid in the wall-normal direction and the third DNS was using finer grid in all three directions.
Results have shown that there are no significant differences in the first-order statistics and spectra for all three cases.
Boiling Curve Measurement of Water Containing Dissolved Carbon Dioxide Around a Heated Wire
Authors: Heydari Ali , Carey V. P. 
Published: November 2021

Abstract
Proper thermal treatment of metals in metal processing plants is important both in terms of quality and economy of the final product. Addition of a highly soluble gas such as carbon dioxide to water has been shown to create an excellent quenching medium for metal objects in metal working processes. It causes slower rate of cooling due to the insulating effect of carbon dioxide on the surface of immersed metal objects which as a result hinders residual stress build up and warpage commonly observed in quenching metal objects in cold water. Additionally, absence of carbon dioxide-filled bubbles on the surface of quenching metal object causes cold water-like cooling of the surface, producing rapid cooling of the objects. In this study, boiling heat transfer characteristics of an electrically heated wire immersed in water mixed with different concentrations of carbon dioxide at various atmospheric and sub-atmospheric pressures are obtained and compared. The results indicate that the boiling behavior and heat transfer characteristics of carbon dioxide-water solution make it a favorable substitute to cold and hot water traditionally used as the heat transfer fluid in metal processing plants.
Effect of Fouling on Nucleate Pool Boiling and Critical Heat Flux
Authors: Fukada Yusuke , Haze Ikuya , Horiki Sachiyo , Osakabe Masahiro 
Published: November 2021

Abstract
Pool boiling experiment with a platinum wire was performed in earth and micro gravity. Bare surface and fouling surface with scale of calcium carbonate was used. The wettability on the scale surface was higher than that on the bare surface. The critical heat flux (CHF) was measured and movies of the bubbling were taken with a high-speed video camera. The more vigorous bubbling was observed on the scale surface compared to that on the bare surface at the same heat flux. The scale surface became thermal resistance and the boiling curve on the scale surface eventually shifted to the right side of that on the bare surface. However, the critical heat flux on the scale surface was higher than that on the bare surface. On the scale surface, the departure diameter of bubbles is relatively smaller than that on the bare surface. The smaller diameter of bubbles detaching from the scale surface is considered to be due to the high wettability. As the result, the coalescent of bubbles near the surface was prevented and the CHF was delayed and increased on the scale surface compared to that on the bare surface.
A Finite-Volume Based Time-Splitting Scheme for Computation of Electrodeposition
Authors: Xia Chunmei , Murthy Jayathi Y. 
Published: November 2021

Abstract
The final step in the LIGA process for manufacturing metallic microstructures is the electroplating of the metal part. The electroplating process can be described by homogeneous dissociation reactions in the electrolyte bath and finite rate surface reactions on the electrode. In this paper we develop a finite volume method for computing electrodeposition in the LIGA process. We employ a time splitting algorithm for coupling the bulk and surface reactions. As an alternative, the species concentration field is solved over the whole domain using a direct method. The two methods are compared to establish the validity and efficiency of the time-splitting algorithm.
Thermal Non-Equilibrium Effects at the Stagnation Wall in the Unsteady Micro-Flow
Authors: Park Jae Hyun , Baek Seung Wook 
Published: November 2021

Abstract
In the present study, the non-equilibrium effects at the stagnation wall in one-dimensional unsteady micro-flow responding to the external sinusoidal oscillation are investigated. The fluctuating behavior of the rarefied medium is simulated by employing the unsteady DSMC method for various conditions with the acoustic Reynolds number and the Knudsen number. The heat fluxes calculated from Maxwell-Smoluchowski’s relation and its higher order modifications are compared with the direct DSMC result. Consequently, it is found that there exists the non-equilibrium effect at the stagnation wall especially when the number of reflected molecules from the diffuse wall was small.
Pool Boiling of High-Frequency Conductors
Authors: Wright S. E. , Konecni S. , Ammerman C. N. , Sims J. R. 
Published: November 2021

Abstract
This study presents development of a unique, powerful method for cooling high-frequency, AC conductors that can benefit end users of transformer windings, electrical machine windings, and magnet coils. This method of heat removal involves boiling a dielectric, fluorinert refrigerant that is in direct contact with litz wire conductors. A pool boiling test vessel is constructed, which provides for temperature control of the pool of fluorinert liquid. The test vessel is fitted with viewing ports so that the experiments are observed and studied with the aid of high-speed photography. Tests are performed on a variety of litz wire conductors. The boiling heat transfer coefficient is dependent on the conductor surface roughness. The size of the features on the conductor surface depends on the single-strand wire gage from which the conductor is constructed. All tests are performed with the conductors mounted horizontally. These tests are performed using a DC power supply. The results of these experiments will aid in the design of future cooling systems.
Air-Water Transient Heat Transfer in a Stirred Tank
Authors: Dubovsky V. , Ziskind G. , Letan R. 
Published: November 2021

Abstract
The work is concerned with a stirred tank in which water is cooled batchwise by a continuous stream of bubbling air. The work is experimental, and the phenomena are simulated by an analytical model.
The experiments include direct contact of air bubbles with the stirred water, heat transfer to the ambient air through the interface, and heat transfer through the walls to cooling water in a jacket by natural or forced convection, or to ambient air by natural convection.
Heat-transfer coefficients are calculated in all the cases studied, starting with free convection and proceeding systematically to a complex interaction of mechanical stirring and agitation caused by dispersed air bubbles. Special attention is given to such phenomena as enhanced heat transfer through the liquid-air interface as a result of mixing and bubbly flow.
Theoretical considerations lead to a mathematical model that takes into account the heat-transfer mechanisms studied. The model simulations compare well with the experimental measurements.