bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction Between Wire and Ingot in Wiresaw Slicing
Authors: Yang Fuqian , Li J. C. M. , Kao Imin 
Published: December 2021

Abstract
The deformation of the wire in the wiresaw slicing process was studied by considering directly the mechanical interaction between the wire and the ingot. The wire tension on the upstream is larger than on the downstream due to the friction force between the wire and the ingot. The tension difference across the cutting zone increases with friction and the span of the contact zone. The pressure in the contact zone increases from the entrance to the exit if the wire bending stiffness is ignored. The finite element results show that the wire bending stiffness plays an important role in the wire deformation. Higher wire bending stiffness (larger wire size) generates higher force acting onto the ingot for the same amount of wire deformation, which will leads to higher material removal rate and kerf loss. While larger wire span will reduce the force acting onto the ingot for a given ingot displacement in the direction perpendicular to the wire.
Process Characterization and the Effect of Process Defects on Flip Chip Reliability
Authors: Lewis Brian J. , Sasso Hilary 
Published: December 2021

Abstract
Processing fine pitch flip chip devices continues to pose problems for packaging and manufacturing engineers. Optimizing process parameters such that defects are limited and long-term reliability of the assembly is increased can be a very tedious task. Parameters that effect the robustness of the process include the flux type and placement parameters. Ultimately, these process parameters can effect the long-term reliability of the flip chip assembly by either inhibiting or inducing process defects. Therefore, care is taken to develop a process that is robust enough to supply high yields and long term reliability, but still remains compatible with a standard surface mount technology process. This is where process optimization becomes most critical and difficult. What is the optimum height of the flux thin film used for a dip process? What force is required to insure that the solder bumps make contact with the pads? What are the limiting boundaries in which high yields and high reliabilities are achieved, while maintaining a streamlined, proven process?
The following study evaluates a set of process parameters and their impact on process defects and reliability. The study evaluates process parameters including, flux type, flux application parameters, placement force and placement accuracy to determine their impact. Solder voiding, inadequate solder wetting, and crack propagation and delamination in the underfill layer are defects examined in the study. Assemblies will be subjected to liquid-to-liquid thermal shock testing (−55° C to 125°C) to determine failure modes due to the aforementioned defects. The results will show how changes in process parameters effect yield and reliability.
Major Parameters Affecting Nonlinear Finite Element Simulations of Vehicle Crashes
Authors: Omar Tarek A. , Kan Cing Dao , Bedewi Nabih E. , Eskandarian Azim 
Published: December 2021

Abstract
The three explicit nonlinear Finite Element (FE) codes, LS-DYNA, PAM-CRASH, and RADIOSS are widely used by the automotive companies and government for vehicle and roadside hardware crash simulations. As simulation results from these commercial codes gain wider acceptance for crashworthiness evaluations, the codes also are becoming more sophisticated, including advanced features and options for the user than ever before. While these advanced modeling and simulation features are beneficial to users, they also raise a question regarding the trade off between the FE accuracy and the associated computational time and cost required.
The main objective of this paper is to investigate the effects of the major modeling and simulation features of the commercial FE codes and its direct impact on the simulation accuracy and computational efficiency when solving crash problems. The four major parameters considered in this study are element size/mesh density, shell element formulations, hourglass control form, and integration time step strategy. An intensive parametric study is conducted through FE simulations for quasi-static crush of a simple box beam. The nonlinear, dynamic, explicit FE code, LS-DYNA has been used to perform the parametric study. The accuracy of the FE simulations are measured by comparing the simulation results with experimental test results conducted, in the literature, for the same box beam.
Based on the results of the parametric study, final recommendations and guidelines for choosing the major simulation parameters are offered, to compromise between the FE simulation accuracy and the associated computational time and cost.
The Development of an Aluminum Failure Model for Crashworthiness Design
Authors: Yeh J. R. , Summe T. L. , Seksaria D. C. 
Published: December 2021

Abstract
Providing vehicle occupant protection with advanced structural design for crash energy management is an important consideration in vehicle development. In most cases energy absorption by structural deformation requires a material that is able to accommodate high strain levels in order to prevent or limit material separation which could lead to an undesirable collapse mode and poor energy absorption. Therefore, the development of crashworthy alloys and design concepts is critical to the application of new, lightweight materials in automotive structures. To this end, analytical methods and computer simulations are widely used in the automotive industry to provide a better understanding of the crash mechanisms and to improve the overall development process.
This paper describes the development of a material failure model for efficient design of aluminum alloys, thin-wall components and structures in the consideration of crash energy management. The results of the verification studies are illustrated to demonstrate the accuracy of the failure model for various test conditions. These studies include simulations of coupons and components made from aluminum castings and extrusions under free bend, three-point bend, axial crush and lateral crush tests. The simulations successfully predicted the locations of the major cracks observed in the tested specimens and the energy absorption capability of the specimens.
The major benefits of this tool include (1) Improved alloy development and selection, (2) Reduced number of tests and (3) Decreased design time and cost. These benefits lead to a more optimized design for cost, weight and crash energy management, therefore, facilitating the implementation of aluminum components and structures into automotive applications.
Development of a MADYMO3D Model of the SID-IIs Dummy
Authors: Weerappuli D. Para V. , Chai Li , Barbat Saeed , Wan Deborah , Prasad Priya 
Published: December 2021

Abstract
This paper describes the development of a mathematical model of the new small-sized side impact dummy, SID-IIs. The model, utilizing both lumped-mass and finite element methods of analysis, was developed using the commercially-available software MADYMO3D. As the SID-IIs dummy is based on a 12–13 year-old adolescent/5th percentile female, the head, neck, pelvis, and lower extremities were taken from MADYMO3D lumped-mass models of the Hybrid-III 5th percentile female dummy. The shoulder rib, the three thoracic ribs, the two abdominal ribs, and the foam insert in the dummy jacket were modeled using the finite element method. The ribs were characterized using elastic and visco-elastic material models. The foam insert and the jacket were modeled using foam and elastic material models, respectively. The visco-elastic and foam material constants were determined using data from dynamic tests and an optimization scheme based on the “Box” iteration method.
Preliminary validations of the model were carried out at both sub-assembly and fully-assembled dummy levels. At the sub-assembly level, test results of blunt impacts on the isolated thorax were compared with model results. At the fully-assembled dummy level, data from verification pendulum tests and rigid-wall sled tests were compared with model results.
Generally, for all validation simulations, the model predictions of rib displacements and accelerations showed good agreement with corresponding test results during the loading phase. During unloading, however, there were discrepancies between test data and model results. Additionally, for the rigid wall tests, head acceleration, neck moment, and pelvic acceleration compared well with test data. Overall, the predicted responses provide a reasonable level of confidence in the fidelity of the model.
Modeling the f and j Characteristics for Transverse Flow Through an Offset Strip Fin at Low Reynolds Number
Authors: Muzychka Y. S. , Yovanovich M. M. 
Published: December 2021

Abstract
Analytic models for predicting the thermal-hydraulic characteristics for transverse flow through an offset strip fin array are developed. These models are developed by combining the creeping or low flow asymptotic behaviour with laminar and turbulent boundary layer wake models. Expressions for each of these characteristic regions are developed using fundamental solutions of fluid dynamics and heat transfer. The proposed models are compared with new experimental data for ten offset strip fin configurations. Model predictions are within ± 20 percent for 92 percent of friction factor data and 71 percent for Colburn j factor data.
Numerical Assessment of Hot-Wire Data Deviations in the Vicinity of Walls
Authors: Lange C. F. , Breuer M. , Durst F. , Shi J. M. 
Published: December 2021

Abstract
A detailed numerical assessment of the data deviations and the corresponding corrections needed by hot-wire anemometry (HWA) measurements in wall vicinity was performed. The aim of this study was to determine effective correction functions to HWA data for different wall materials. Two extreme cases were first investigated: a perfectly heat conducting and an adiabatic wall. In the case of the perfectly conducting wall the computed results agreed well with available experimental data for highly conducting materials. However, the numerical results for the case of an adiabatic wall contradicted previous experimental observations based on low-conducting wall materials. A close evaluation of the numerical results led to a better understanding of the physical problem and motivated the simulation of realistic wall materials, such as aluminum and glass.
Heat Transfer From a Moving Surface due to Impinging Jets
Authors: Chattopadhyay H. , Biswas G. , Mitra N. K. 
Published: December 2021

Abstract
Turbulent flow field and heat transfer from an array of impinging slot jets on a moving surface have been numerically investigated by large-eddy simulation (LES) with a dynamic subgrid stress model in the Reynolds number range of 500 to 3000. The surface velocity directed perpendicular to the jet plane is varied up to two times the jet velocity at the nozzle exit. Nusselt number distributions for varying surface velocity are presented. It has been observed that while increasing velocity of the impingement plate reduces heat transfer, distribution of Nusselt number over the impingement surface becomes more and more uniform.
Effect of Fouling on Nucleate Pool Boiling in Microgravity and Earth Gravity
Authors: Motoya Daiju , Haze Ikuya , Osakabe Masahiro 
Published: December 2021

Abstract
Nucleate pool boiling of water on clean and fouling surfaces was conducted in microgravity and earth gravity. The microgravity experiments were conducted in 8 s JAMIC drop shaft in Hokkaido of Japan. Platinum wires of 0.2 mm in diameter with or without fouling scale were used to provide uniform heat flux and measurement of the mean temperature of wires. The generated bubble volume was measured with high-speed video or CCD images.
The more vigorous bubbling was observed on the fouling wire compared to that on the clean wire at a same heat flux both in earth gravity and microgravity. The enhancement of the bubbling was associated with the fact that the hydrophilic porous structure in the fouling scale provided the sufficient number of active sites for bubbling nucleation. The wettability of the surface with the fouling scale was much higher than that of the clean bare surface. The bubble departure diameter on the fouling wire was smaller due to the high wettability than that on the clean wire. The latent heat transportation ratio to the total heat flux was calculated with the generated bubble volume measured with high-speed video or CCD images. The ratio was approximately the same at the clean and fouling wires in spite of the apparent difference in bubbling behavior, but it was significantly affected with the gravity level. The ratio increased with an increase of the heat flux in the earth gravity but it remained at the smaller value in the microgravity. The nucleate heat transfer coefficient on the bare surface did not depend on the gravity levels although the bubbling behavior strongly affected with the gravity level.
As the wire radius is small compared to the capillary length scale in microgravity, a growing and coalescing bubble sometimes completely covered the clean wire, evaporating all liquid in contact with the surface and inducing a transition to film boiling. However, on the fouling wire, many small bubbles were generated and sprang from the surface in various directions in microgravity. The spring out action of bubbles suppressed the transition to the film boiling on the fouling wire in the present experimental range.
Forced-Convective Condensation of Pure Steam and Ammonia-Steam Vapor Mixtures in a Shell-Tube Condenser
Authors: Sharma Ratnesh K. , Hassani Vahab , Mahajan Roop L. 
Published: December 2021

Abstract
In this paper, we present our experimental findings for the forced-convective condensation of pure steam and ammonia-steam vapor mixture in a horizontal annulus in a counter-current shell-tube condenser. Experiments with ammonia-steam mixtures were conducted for ∼ 90% ammonia concentration (by wt.) for vapor inlet mass fluxes ranging from 2 to 5 kg/m2s. The local heat transfer coefficient varied considerably along the condenser and this variation was strongly linked to the condensate flow patterns in the annulus. Based on a condensate drainage model, the flow in the annulus was mapped on to flow maps for horizontal in-tube condensing flows. The delineated flow regimes were utilized to explain augmentation or deterioration of local heat transfer in the condenser. The average heat transfer coefficients are presented as a function of the condensate and vapor Reynolds number for both steam and ammonia-steam mixture. The results for pure steam are higher than those predicted by annular flow correlation developed in the past. For ammonia-steam mixtures, the average heat transfer coefficients are about 16% of those for pure steam due to the vapor layer resistance at the interface.
A Computational Model to Predict Pressure Drop and Droplet Removal Efficiency of Chevron Mist Eliminator
Authors: Rhodes Curtis A. , Khan Jamil A. , Wechsler Harry , Mansson Norman 
Published: December 2021

Abstract
Chevron mist eliminators are widely used in industry to remove liquid droplets from gas streams. A major application of these devices is in the flue gas desulfurization (FGD) of coal burning power plants. Before the exhaust gas is released to the atmosphere, liquid droplets entrained in the gas must be removed. A chevron mist eliminator relies on droplet inertia to cause the droplets to impinge on a surface where they are collected and drained away. The droplet removal efficiency is the critical design parameter of the mist eliminator. Pressure drop and flow capacity is also of major importance.
The droplet removal efficiency, pressure drop, and flow capacity have been investigated experimentally by several investigators. The experimental results were obtained using an air-water system of gas and fluid droplets.
This paper presents the results of a study using computational fluid dynamics to model the two-phase flow through the mist eliminator. Droplet removal efficiency and pressure drop were determined and compared with the experimental results. Three-stage chevron mist eliminator with 45° angle to flow was modeled.
Comparison of the model results with previous experimental results indicated that the model is reasonably accurate. The model predicts pressure drop and the diameter at which 95% of droplets are removed with reasonably good accuracy. However, calculated droplet removal efficiencies of droplets with diameters less than 20μm did not agree well with experiments. The main advantage of the proposed model is that it can be used to predict droplet removal efficiencies for gas streams whose properties differ appreciably from that of an air-water system. Actual gas streams properties are input to the computational model. Therefore, the present model provides an effective and useful design tool.
Experimental Studies of Hydrodynamics and Heat Transfer in Channels With High-Porous Cellular Materials in Single-Phase Forced Convection and Flow Boiling of Working Fluids
Authors: Gortyshov Yury F. , Popov Igor A. , Gulitsky Konstantin E. 
Published: December 2021

Abstract
In this paper we consider experimental studies of hydraulic resistance, surface heat transfer, internal heat exchange and critical heat fluxes for the flow of single-phase and boiling working fluids in channels with high-porous inserts.
Experiments were carried out with more than 40 samples of high-porous cellular materials with the porosity 0.8...0.98 and mean pore diameter 0.62...4 mm and with more than 10 samples of regular porous inserts and porosity ε = 0.512...0.86 and mean pore diameter 1.5...3.5 mm. These samples were made of porcelain, invar, nichrome, bronze and copper.
Hysteresis in Flow in Porous Media With Phase Transitions
Authors: Bedrikovetsky Pavel , Marchesin Dan , Ballin Paulo Roberto 
Published: December 2021

Abstract
Two-phase flow with hysteresis in porous media is described by the Buckley-Leverett model with three types of fractional flow functions: imbibition, drainage and scanning. The mathematical theory for the Riemann problem and for non-self-similar initial-boundary problem is developed. The structure of the solutions is presented and the physical interpretation of the phenomena is discussed.
We obtain the analytical solution for the injection of water slug with gas drive into oil reservoirs. The solutions show that the effect of hysteresis is to decrease gas flux (in the case where the drainage relative permeability lies below the imbibition relative permeability). This effect increases oil recovery for Water-Alternate-Gas injection in oil reservoirs.
Heat Transfer in Flow Freezing Over the Isothermal Cylinders
Authors: Sadeghipour Sadegh M. , Shotorban Babak B. 
Published: December 2021

Abstract
Heat transfer in the transient flow freezing on the external surfaces of circular cylinders in a bundle with in-line arrangement is studied, numerically. Low Reynolds numbers are considered, therefore, flow is assumed to be symmetric.
Local and average Nusselt numbers are calculated, at different time steps. The steady state average Nusselt numbers are compared with the reported experimental results. Their agreement is reasonable.
Melting Rate of a Solid With Periodic Melt Removal
Authors: Nemchinsky Valerian 
Published: December 2021

Abstract
The melting rate of a solid, subjected to a heat flux at its surface, changes with time. When a fresh unmelted surface is first exposed to a heat source, the melting isotherm moves quickly inside the solid. Then its motion slows down: this decrease in melting rate is obviously because of increasing thermal resistance of the growing liquid layer that separates solid-liquid interface from the heat source. If the liquid layer is not removed, the melting rate approaches zero. The resultant melting rate depends on the manner in which the melt is removed. In a number of cases of practical interest, the melt is removed not continuously but periodically, in the form of drops. For example, during arc welding with a consumable electrode, these drops are accumulated at the tip of the electrode. When the drop becomes big enough, it is detached from the electrode under action of gravity or electromagnetic force the melt is removed not continuously but periodically, in the form of drops. A simple approximate method is suggested to calculate the melting rate of a solid in the case when melt is removed periodically in form of drops. The method allows one to consider separately the heat transfer in the solid and in the liquid and, thus, to include different heat processes in both phases. Good agreement was demonstrated for exact and approximate solutions for a wide range of parameters.
On Physical Mechanisms of Mushy Zone Formation in Solidification of Pure Semitransparent Materials
Authors: Wang G.-X. , Yao Chengcai , Chung B. T. F. 
Published: December 2021

Abstract
Two different models, the isothermal mushy zone model and the non-equilibrium planar interface model, are employed to solve the solidification problem of a one-dimensional semitransparent slab subject to radiative and convective cooling at the surface. The mushy zone model is based on the assumption of local equilibrium and predicts the formation of a mushy zone as soon as the temperature of the slab surface reaches the equilibrium melting temperature. The non-equilibrium planar interface model, on the other hand, assumes a stable planar solid/liquid interface during solidification. It allows the existence of melt undercooling at the interface and in the bulk melt. The stability of the planar interface is then examined approximately using the linear stability criterion derived for an opaque material. It is found that a planar interface would be stable even if a large undercooling is generated in the bulk melt in front of the interface. If the rate of external heat transfer is small, however, the planar interface will break down and develop into thermal cells or dendrites. In addition, a transition from a mushy zone to a planar interface is also observed. Based on these results, the thermodynamics and kinetics of crystalline nucleation and growth are examined to illustrate the physical mechanisms of mushy zone formation during solidification of a semi transparent material. It is suggested that the isothermal mushy model and the planar interface model are valid only under corresponding processing conditions, and more research is needed to provide a complete description of the process.
Pool Boiling Heat Transfer in Aqueous Surfactant Solutions
Authors: Wasekar Vivek M. , Manglik Raj M. 
Published: December 2021

Abstract
Saturated, nucleate pool boiling of aqueous surfactant solutions on a horizontal, cylindrical heater has been experimentally investigated. Sodium dodecyl or lauryl sulfate (SDS or SLS), an anionic surfactant is employed. Boiling performance, relative to that for pure water, is found to be enhanced significantly by the presence of SDS, with an early onset of nucleate boiling. An optimum level of enhancement is observed in solutions at or near critical micelle concentration of the surfactant; the enhancement decreases considerably in higher concentration solutions. The dynamic surface tension measurements indicate a considerable influence of temperature on the overall adsorption isotherm. The diffusion kinetics of surfactant molecules and micelles is, therefore, expected to be quite different at boiling temperature than at room temperature. This greatly modifies the boiling mechanism, that is generally characterized by the formation of smaller-size bubbles with increased departure frequencies, and a decreased tendency to coalesce which causes considerable foaming.