Academic literature on the topic 'CFD process model'
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Journal articles on the topic "CFD process model"
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Ta, C. T., J. Beckley, and A. Eades. "A multiphase CFD model of DAF process." Water Science and Technology 43, no. 8 (April 1, 2001): 153–57. http://dx.doi.org/10.2166/wst.2001.0488.
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A Eulerian-Eulerian multiphase CFD model is employed for the air/water flow. A 3D structure grid is used to incorporate the air nozzle and tank geometry. The fixed frictionless wall boundary approximating the free surface acts as a sink to allow the air bubbles to escape. The air/water volume fraction in the flotation tank is evaluated to determine the effective air/water fluid density. The floc particle is then introduced and is tracked in the air/water fluid using a disperse Lagrangean model. Fate of these flocs depends on their sizes and density. Flocs therefore can either escape through the top water surface, settles in the main tank or breakthrough under the outlet weir. The CFD model is developed for a full scale DAF tank to predict the flow dynamic, particle removal and settled solid profile. The general flow pattern is compared with flow visualisation using the underwater camera. Comparison of average fluid velocities is carried out using acoustic Doppler velocimetry ADV measurement.
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Słupik, Łukasz, Adam Fic, Zbigniew Buliński, Andrzej J. Nowak, Ludwik Kosyrczyk, and Grzegorz Łabojko. "CFD model of the coal carbonization process." Fuel 150 (June 2015): 415–24. http://dx.doi.org/10.1016/j.fuel.2015.02.044.
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Agonafer, D., and A. Vimba. "Solid Model Based Preprocessor to CFD Code for Applications to Electronic Cooling Systems." Journal of Electronic Packaging 119, no. 2 (June 1, 1997): 138–43. http://dx.doi.org/10.1115/1.2792220.
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The use of a solid model based Computer Aided Design (CAD) tool as a preprocessor to a finite control-volume based Computational Fluid Dynamics (CFD) code is presented. Preprocessing includes geometry description, grid generation, definition of material properties, application of boundary conditions, and definition of solution control parameters. The CAD based preprocessor, as opposed to traditional finite control-volume preprocessors, provides the above capabilities in a powerful graphic environment. Using a solid model based CAD tool, work is reduced, and visualization is enhanced employing the capabilities of the three-dimensional solid modeler. In addition, a technique which categorizes control volumes into groups comprising the solid and fluid portions of the problem domain is presented. At the completion of preprocessing, a model appropriate as input to a CFD code is generated. This model is then solved using the CFD program. The process is shown in a tutorial form by considering a two-dimensional turbulent flow problem in an electronic card on board package. Although the methodology shown in this paper focuses on specific CFD and Solid Model programs, the concept can readily be applied to other CFD and/or Solid Model programs.
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Boroń, Sylwia, and Tomasz Wdowiak. "Numerical representation of extinguishing gas discharge process." MATEC Web of Conferences 247 (2018): 00043. http://dx.doi.org/10.1051/matecconf/201824700043.
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The aim of the work was to provide the analysis of the use of computational fluid dynamics (CFD) for modeling the stage of extinguishing gas discharge to a compartment, which is not taking into account in standard models. The CFD techniques may let to predict gas parameters in dependence of various conditions in a protected area. The investigations were carried out with software ANSYS Fluent 18.2, using Realizable k-ε model and SIMPLE algorithm. The numerical model was validated using experimental data. The subject of the study were standard and newly proposed inert gases. The results showed that adequate selection of input parameter let to simulate the gas discharge stage with high accuracy. The numerical results have a good agreement with the experimental results. The conclusions provide recommendations for the gas discharge prediction based on CFD technique.
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Nastac, L., F. R. Dax, and W. Hanusiak. "Methodology for modeling the EB-PVD coating process." Journal de Physique IV 120 (December 2004): 307–14. http://dx.doi.org/10.1051/jp4:2004120035.
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This paper presents a methodology for modeling and analyzing the Electron Beam-Physical Vapor Deposition (EB-PVD) coating process. The Knudsen (Kn) number for the current processing conditions is near but smaller than 0.1 so the continuum approach (based on Navier-Stokes equations) is still valid though the dilute gas regime is considered. The methodology developed in this work is applied to optimization of the evaporation and deposition rates and patterns of metal vapors on ceramic substrates. The methodology is based on the numerical solution of evaporation, fluid flow, species transfer, heat transfer, and a deposition/condensation kinetics model. The models developed for the analysis of the coating process include an ingot EB-melting/evaporation model, a computational fluid dynamics (CFD)-vapor distribution/plume dynamics model (chamber model), and a coating-kinetics model. Numerical simulations at the macro-level were conducted using CFD software. The results from the ingot EB-melting/evaporation model are used as input data in the CFD-vapor distribution model. The coating-kinetics model uses as input, data pressure, temperature, and concentration of Ti-6Al-4V (Ti-6-4) vapors computed with the CFD model. To account for the rarefied gas regime (where Knudsen number [Kn] could be larger than 0.1), appropriate low-pressure “boundary slip conditions” with momentum and thermal accommodation coefficients as a function of Kn were used. Numerical results for temperature and Ti-6-4 vapor concentration profiles in the chamber are presented. Experiments conducted at FMW Composite Systems Inc. are also presented.
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Wachowicz, Jan, Jacek Marian Łączny, Sebastian Iwaszenko, Tomasz Janoszek, and Magdalena Cempa-Balewicz. "Modelling of Underground Coal Gasification Process Using CFD Methods / Modelowanie Procesu Podziemnego Zgazowania Węgla Kamiennego Z Zastosowaniem Metod CFD." Archives of Mining Sciences 60, no. 3 (September 1, 2015): 663–76. http://dx.doi.org/10.1515/amsc-2015-0043.
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Abstract The results of model studies involving numerical simulation of underground coal gasification process are presented. For the purpose of the study, the software of computational fluid dynamics (CFD) was selected for simulation of underground coal gasification. Based on the review of the literature, it was decided that ANSYS-Fluent will be used as software for the performance of model studies. The ANSYS- -Fluent software was used for numerical calculations in order to identify the distribution of changes in the concentration of syngas components as a function of duration of coal gasification process. The nature of the calculations was predictive. A geometric model has been developed based on construction data of the georeactor used during the researches in Experimental Mine “Barbara” and Coal Mine “Wieczorek” and it was prepared by generating a numerical grid. Data concerning the georeactor power supply method and the parameters maintained during the process used to define the numerical model. Some part of data was supplemented based on the literature sources. The main assumption was to base the simulation of the georeactor operation on a mathematical models describing reactive fluid flow. Components of the process gas and the gasification agent move along the gasification channel and simulate physicochemical phenomena associated with the transfer of mass and energy as well as chemical reactions (together with the energy effect). Chemical reactions of the gasification process are based on a kinetic equation which determines the course of a particular type of equation of chemical coal gasification. The interaction of gas with the surrounding coal layer has also been described as a part of the model. The description concerned the transport of thermal energy. The coal seam and the mass rock are treated as a homogeneous body. Modelling studies assumed the coal gasification process is carried out with the participation of separately oxygen and air as a gasification agent, under the specific conditions of the georeactor operations within the time interval of 100 hours and 305 hours. The results of the numerical solution have been compared with the results of experimental results under in-situ conditions.
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Wang, Gang, Shou Mei Xiong, and Yi Ming Rong. "CFD-Based Multicomponent Model for Solidification of Casting Process." Advanced Materials Research 189-193 (February 2011): 1656–59. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1656.
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The solidification model is vital to the simulation of casting process with mushy zoned involved. The author has built a multicomponent model for solidification which is derived from the principles of fluid dynamics. The model has been realized on the commercial CFD package, in which the solid and liquid of metal are united in one frame. In this model the flow behavior of solid is constrained by increasing the viscosity, the latent heat and the buoyancy are also considered, and the key point is the effect of solid fraction on the flow in the mushy zone. The details of flow can be captured even in the mushy zone by using this model.
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Xu, Qing, Yu-Xing Li, Xiao-Ning Li, Jia-Bin Wang, Fan Yang, Yi Yang, and Tian-Ling Ren. "Simulation of SiO2 etching in an inductively coupled CF4 plasma." Modern Physics Letters B 31, no. 06 (February 28, 2017): 1750042. http://dx.doi.org/10.1142/s0217984917500427.
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Plasma etching technology is an indispensable processing method in the manufacturing process of semiconductor devices. Because of the high fluorine/carbon ratio of CF4, the CF4 gas is often used for etching SiO2. A commercial software ESI-CFD is used to simulate the process of plasma etching with an inductively coupled plasma model. For the simulation part, CFD-ACE is used to simulate the chamber, and CFD-TOPO is used to simulate the surface of the sample. The effects of chamber pressure, bias voltage and ICP power on the reactant particles were investigated, and the etching profiles of SiO2 were obtained. Simulation can be used to predict the effects of reaction conditions on the density, energy and angular distributions of reactant particles, which can play a good role in guiding the etching process.
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CHO, SU K., and VAMSHI M. KORIVI. "PORT DESIGN OPTIMIZATION USING CFD ANALYSIS." Journal of Advanced Manufacturing Systems 03, no. 01 (June 2004): 21–32. http://dx.doi.org/10.1142/s0219686704000375.
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Shape of ports that are part of an engine cylinder head is vital to engine performance and emissions. The advance of CFD (Computation Fluid Dynamics) analysis technology helps designers run the simulation to improve the port design and to provide the better model for a flow bench test. This paper presents the automation of design optimization process integrating CAD modeling, mesh generation and CFD simulation.
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Janoszek, Tomasz, Krzysztof Stańczyk, and Adam Smoliński. "Modelling Test of Autothermal Gasification Process Using CFD." Archives of Mining Sciences 62, no. 2 (June 27, 2017): 253–68. http://dx.doi.org/10.1515/amsc-2017-0019.
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AbstractThere are many complex physical and chemical processes, which take place among the most notable are the chemical reactions, mass and energy transport, and phase transitions. The process itself takes place in a block of coal, which properties are variable and not always easy to determine in the whole volume. The complexity of the phenomena results in the need for a construction of a complex model in order to study the process on the basis of simulation. In the present study attempts to develop a numerical model of the fixed bed coal gasification process in homogeneous solid block with a given geometry were mode. On the basis of analysis and description of the underground coal gasification simulated in the ex-situ experiment, a numerical model of the coal gasification process was developed. The model was implemented with the use of computational fluid dynamic CFD methods. Simulations were conducted using commercial numerical CFD code and the results were verified with the experimental data.
Dissertations / Theses on the topic "CFD process model"
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Bai, Haitong. "A Study of the Swirling Flow Pattern when Using TurboSwirl in the Casting Process." Doctoral thesis, KTH, Tillämpad processmetallurgi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-196806.
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The use of a swirling flow can provide a more uniform velocity distribution and a calmer filling condition according to previous studies of both ingot and continuous casting processes of steel. However, the existing swirling flow generation methods developed in last decades all have some limitations. Recently, a new swirling flow generator, the TurboSwirl device, was proposed. In this work, the convergent nozzle was studied with different angles. The maximum wall shear stress can be reduced by changing the convergent angle between 40º and 60º to obtain a higher swirl intensity. Also, a lower maximum axial velocity can be obtained with a smaller convergent angle. Furthermore, the maximum axial velocity and wall shear stress can also be affected by moving the location of the vertical runner. A water model experiment was carried out to verify the simulation results of the effect of the convergent angle on the swirling flow pattern. The shape of the air-core vortex in the water model experiment could only be accurately simulated by using the Reynolds Stress Model (RSM). The simulation results were also validated by the measured radial velocity in the vertical runner by the ultrasonic velocity profiler (UVP). The TurboSwirl was reversed and connected to a traditional SEN to generate the swirling flow. The periodic characteristic of the swirling flow and asymmetry flow pattern were observed in both the simulated and measured results. The detached eddy simulation (DES) turbulence model was used to catch the time-dependent flow pattern and the predicted results agree well with measured axial and tangential velocities. This new design of the SEN with the reverse TurboSwirl could provide an almost equivalent strength of the swirling flow generated by an electromagnetic swirling flow generator. It can also reduce the downward axial velocities in the center of the SEN outlet and obtain a calmer meniscus and internal flow in the mold.Tidigare studier visar att ett roterande flöde kan ge en mer likformig hastighetsfördelning och en lugnare fyllning i både göt- och stränggjutning av stål. De befintliga metoderna för att generera ett roterande flöde har vissa begränsningar. En ny metod för att generera det roterande flödet, en så kallad TurboSwirl, föreslogs nyligen. I detta arbete undersöktes ett konvergent munstycke med olika vinklar för att se hur detta påverkade det roterande flödet som genererades i anordningen. Resultaten visar att skjuvspänningen i systemet kan reduceras genom att ändra munstyckets vinkel mellan 40º till 60º. En lägre maximal axiell hastighet kan också uppnås med en mindre konvergent vinkel på munstycket. Det är även möjligt att påverka den maximala axiella hastigheten och skjuvspänningen i systemet genom att förflytta den vertikala kanalen i anordningen. Vattenmodellexperiment har utförts för att validera simuleringsresultaten. Det kraftigt roterande flödet kunde endast beskrivas väl av Reynolds Stress Model (RSM). Validering utfördes också genom att mäta den radiella hastigheten i den vertikala kanalen med en Ultrasonic Velocity Profiler (UVP). TurboSwirl-anordningen vändes och kopplades till gjutröret för att generera det roterande flödet. Detta studerades både med numeriska modeller och med vattenmodellering. Ett periodiskt asymmetriskt roterande flöde observerades både i numeriska modellerna och i vattenmodellerna. För att modellera detta periodiska flöde så användes detached eddy simulation (DES) modellen. Resultaten då denna modell användes stämmer väl med de experimentella mätningarna. Denna nya design med TurboSwirl kan uppnå liknande styrka på det roterande flödet som när elektromagnetisk omrörning användes. Det resulterande roterande flödet leder till en lägre axiell hastighet i gjutröret samt en lugnare yta och ett lugnare flöde i kokillen.
QC 20161123
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Ma, Rui. "Development and experimental validation of a CFD model for Pd-based membrane technology in H2 separation and process intensification." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/544.
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Syngas production and hydrogen separation technologies are very mature, and also extremely important for energy and chemical industries. Furthermore, these processes are the most expensive elements for many applications such as hydrogen production from renewable sources. Enhancing or intensifying these very mature technologies is very challenging, but would have tremendous impact on the performance and economics of many processes. Traditional Integrated Gasification Combined Cycle (IGCC) for syngas production need to include a carbon capture process in order to regulate their carbon dioxide emission as more and more countries and regions have implemented carbon tax policy. Integration of this process with Pd membrane has long been considered a key component to make it more feasible. With these two technologies combined together, we can produce high purity hydrogen while capturing carbon dioxide and toxic gases from the syngas product. Besides, although manufacturing the membrane reactor is expensive, after considering the carbon tax factor, it actually is more economically preferable compare with the traditional Pressure Swing Adsorption (PSA) process. Most research on Pd membrane technology has been conducted at lab scale; nonetheless, the contribution of a palladium membrane technology to economic and societal development requires its commercialization, diffusion and utilization. To generate enough incentives for commercialization, it is necessary to demonstrate the scalability and robustness of the membranes in industrial settings. Consequently, a multitube membrane module suitable for IGCC system was designed and manufactured and sent to National Carbon Capture Center (NCCC) for testing. This work developed a Computational Fluid Dynamics (CFD) model for the module and validated the model utilizing the pilot-scale experimental data generated under industrial conditions. The model was then up-scaled and used to determine the intrinsic phenomena of palladium membrane scale up. This study reveals the technical/engineering requirements for the effective design of large-scale multitube membrane modules. Mass transfer limitations and concentration polarization effects were studied quantitatively with the developed model. Methods for diminishing the concentration polarization effect were proposed and tested through the simulations such as i) increasing convective forces and ii) designing baffles to create gas recirculation. For scaled-up membrane modules, mass transfer limitation is an important parameter to consider as large modules showed severe concentration polarization effects. IGCC systems produce H2 from coal combustion; other ways of H2 production include steam-reforming processes, using natural gas or bio-ethanol as the reactant. The product contains a mixture of H2, CH4, CO, CO2 and steam. Thus, steam-reforming processes are often followed by a Pressure Swing Adsorption (PSA) unit in order to obtain pure hydrogen. Palladium membrane, on the other hand, can be integrated with steam-reforming processes and achieve the simultaneous production and purification of H2 in a single unit by reaching process intensification. Higher H2 production rate can be reached by process intensification as one of the products H2 is constantly being removed. Temperature control is a very important topic in steam reforming processes, as the reaction is overall highly endothermic; although implementing an in-unit membrane improves H2 production rate, it also makes the temperature control more difficult as the reaction equilibrium is altered by the removal of one of the products H2. Hereby, an experimental study of catalytic membrane reactor (CMR) was carried out along with both isothermal and non-isothermal CFD simulations that are validated by the experimental data in order to visualize the temperature distribution inside the reactor and understand the influence of the operating conditions including temperature, pressure and the sweep gas flow patter on the permeate side.
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Dohnal, Miloslav. "Výpočtová analýza proudění v bubnové sušičce prádla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231275.
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The aim of this work is to create a computational model of radial industrial tumble dryers, to calculate and identify the amount of air that flows through the inside of the drum itself. The calculation will be performed via computational fluid dynamics (CFD). Furthermore, compile transient balance model of mentioned dryers. Perform simulation balance model and compare the results of simulations with experimental measurements. By comparing the experimental data and simulation to determine the degrees of freedom of balance model and evaluate their impact on the assembled transient model. For a better understanding of the drying process, there is constructed a system of differential equations describing heat and moisture within the material being dried on a simple model. In the section devoted to the computational analysis of fluid flow is analyzed existing geometry of the drum, which has a major impact on the flow of air inside the drum itself. Following describes how to simplify its complex geometry entering the computational fluid dynamics. Then, there is carried out a simulation of fluid flow inside the tumble dryers using MRF and Sliding Mesh models. Finally, there is an analysis of the data obtained and determined the average amount of air flowing through the drum itself. On the contrary, the aim of the work is not to create another text tool for students engaged in CFD theme.
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Tan, Zhe. "Modeling of Initial Mold Filling in Uphill Teeming Process Considering a Trumpet." Licentiate thesis, KTH, Tillämpad processmetallurgi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-73948.
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The flow pattern in the uphill teeming process has been found to be closely related to the quality of ingots and further to affect the yield of ingot production, which is crucial for the steel making process. The formation of non-metallic inclusion and entrapment of mold flux has been considered to be affected by the flow pattern in the gating system and molds by many previous researchers. The aim of this study is to investigate the flow pattern of steel in the gating system and molds during the initial filling stage. In addition, to study the utilization of swirl blade implemented at the bottom of the vertical runner on the improvement of initial filling condition in the mold. A three dimensional model of two molds gating system for 6.2 ton ingots from Scana Steel was adopted in the present work. A reduced geometry model including one mold and a runner, based on the method from previous researchers, was also used for comparison with the current more extensive model. Moreover, a reduced geometry model including one swirl blade and a runner was simulated to find effects of an increased-length vertical runner on the flow pattern improvement at the vertical runner outlet. Flow pattern, hump height and wall shear stress were respectively studied. A reduced geometry with homogenous inlet conditions fails to describe the fluctuating conditions present as the steel enters the mold. However, the trends are very similar when comparing the (hump height-surface height) evolution over time. The implementation of swirl blades gives a chaotic initial filling condition with a considerable amount of droplets being created when steel enters the molds during the first couple of seconds. However, a more calm filling condition with less fluctuation is achieved at the molds after a short while. Moreover, the orientation of the swirl blades affects he flow pattern of the steel. A proper placement of a swirl blade improves the initial filling conditions. The utilization of swirl blades might initially result in larger hump height. However, it gives fewer fluctuations as the casting proceeds. In the model without swirl blades, the maximum wall shear stress fluctuates with a descending trend as the filling proceeds. An implementation of swirl blades can decrease and stabilize the wall shear stress in the gating system. A special attention should be made in choosing refractory at the center stone, the horizontal runner near center stone and the vertical runner at the elbow. This is where the wall shear stress values are highest or where the exposure times are long.QC 20120203
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Tan, Zhe. "Some Aspects of Improving Initial Filling Conditions and Steel Cleanliness by Flow Pattern Control Using a Swirling Flow in the Uphill Teeming Process." Doctoral thesis, KTH, Tillämpad processmetallurgi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-117718.
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The flow pattern has widely been recognized to have an impact on the exogenous non-metallic inclusion generation in the gating system and mold flux entrapment in the uphill teeming process. Thus, a well-controlled flow pattern during the teeming process can improve the quality of ingots and further increase the yield during steel production. The current study focused on investigating and optimizing the flow pattern of steel in the gating system and molds to improve steel cleanliness during the initial filling moment. A mathematical model considering a trumpet was initially compared to a reduced model only considering part of the runner channel. Thereafter, the influence of swirl blades implemented at the bottom of the vertical runner on the improvement of initial filling conditions in the molds was investigated in a model considering the entire mold system including a trumpet. The effects of a swirl blade orientation on a swirling flow were further discussed. The simulation results, when utilizing swirl blades, were also verified by plant trials performed at Scana Steel. In addition, a new novel swirling flow generation component, TurboSwirl, was studied in a model considering the entire mold system including a trumpet. The model was based on modifications of the refractory geometry at the elbow of the runners near the mold without the usage of an inserted flow control device in the gating system. Owing to its great potential for improving the flow pattern of steel during the initial filling moment, the effect of TurboSwirl on steel cleanliness was also studied. The results showed that the initial filling conditions during the uphill teeming process can be improved by using a swirl blade or a TurboSwirl in the gating system. This makes it possible to further decrease the initial position of mold powder bags. In addition, it reduces the possibilities of exogenous non-metallic inclusion generation in the gating system as well as mold flux entrapment in the mold during the uphill teeming process. However, the utilization of swirl blades created a considerable amount of droplets when steel entered the molds during the first couple of seconds, which also was verified by the plant trials. The introduction of TurboSwirl showed a greater potential than a swirl blade due to a more evenly distributed swirling flow. The DPM model adopted in the simulations revealed that the TurboSwirl can improve steel cleanliness by increasing the non-metallic inclusion collision rate both with respect to Stokes and turbulent collisions.QC 20130204
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Martí, Gómez-Aldaraví Pedro. "DEVELOPMENT OF A COMPUTATIONAL MODEL FOR A SIMULTANEOUS SIMULATION OF INTERNAL FLOW AND SPRAY BREAK-UP OF THE DIESEL INJECTION PROCESS." Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/43719.
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El proceso de atomización desde una vena o lámina líquida hasta multitud de gotas dispersas en un medio gaseoso ha sido un fenómeno de interés desde hace varias décadas, especialmente en el campo de los motores de combustión interna alternativos. Multitud de estudios experimentales han sido publicados al respecto, pues una buena mezcla de aire-combustible asegura una evaporación y combustión mucho más eficientes, aumentando la potencia del motor y reduciendo la cantidad de contaminantes emitidos. Con el auge de las técnicas computacionales, muchos modelos han sido desarrollados para estudiar este proceso de atomización y mezcla. Uno de los últimos modelos que han aparecido es el llamado ELSA (Eulerian-Lagrangian Spray Atomization), que utiliza un modelo Euleriano para la parte densa del chorro y cambia a un modelo Lagrangiano cuando la concentración de líquido es suficientemente pequeña, aprovechando de esta manera las ventajas de ambos. En el presente trabajo se ha desarrollado un modelo puramente Euleriano para estudiar la influencia de la geometría interna de la tobera de inyección en el proceso de atomización y mezcla. Se ha estudiado únicamente el proceso de inyección diésel. Este modelo permite resolver en un único dominio el flujo interno y el externo, evitando así las comunes simplificaciones y limitaciones de la interpolación entre ambos dominios resueltos por separado. Los resultados actuales son prometedores, el modelo predice con un error aceptable la penetración del chorro, el flujo másico y de cantidad de movimiento, los perfiles de velocidad y concentración, así como otros parámetros característicos del chorro.Martí Gómez-Aldaraví, P. (2014). DEVELOPMENT OF A COMPUTATIONAL MODEL FOR A SIMULTANEOUS SIMULATION OF INTERNAL FLOW AND SPRAY BREAK-UP OF THE DIESEL INJECTION PROCESS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/43719
TESIS
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Johnson, Ryan William. "Process Development for the Manufacture of an Integrated Dispenser Cathode Assembly Using Laser Chemical Vapor Deposition." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/6978.
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Laser Chemical Vapor Deposition (LCVD) has been shown to have great potential for the manufacture of small, complex, two or three dimensional metal and ceramic parts. One of the most promising applications of the technology is in the fabrication of an integrated dispenser cathode assembly. This application requires the deposition of a boron nitridemolybdenum composite structure. In order to realize this structure, work was done to improve the control and understanding of the LCVD process and to determine experimental conditions conducive to the growth of the required materials. A series of carbon fiber and line deposition studies were used to characterize processshape relationships and study the kinetics of carbon LCVD. These studies provided a foundation for the fabrication of the first high aspect ratio multilayered LCVD wall structures. The kinetics studies enabled the formulation of an advanced computational model in the FLUENT CFD package for studying energy transport, mass and momentum transport, and species transport within a forced flow LCVD environment. The model was applied to two different material systems and used to quantify deposition rates and identify ratelimiting regimes. A computational thermalstructural model was also developed using the ANSYS software package to study the thermal stress state within an LCVD deposit during growth. Georgia Techs LCVD system was modified and used to characterize both boron nitride and molybdenum deposition independently. The focus was on understanding the relations among process parameters and deposit shape. Boron nitride was deposited using a B3N3H6-N2 mixture and growth was characterized by sporadic nucleation followed by rapid bulk growth. Molybdenum was deposited from the MoCl5-H2 system and showed slow, but stable growth. Each material was used to grow both fibers and lines. The fabrication of a boron nitridemolybdenum composite was also demonstrated. In sum, this work served to both advance the general science of Laser Chemical Vapor Deposition and to elucidate the practicality of fabricating ceramicmetal composites using the process.
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Chen, Jie. "Modelling of Laser Welding of Aluminium using COMSOL Multiphysics." Thesis, KTH, Materialvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284448.
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This thesis presents a modelling approach of laser welding process of aluminium alloy from the thermo-mechanical point of view to evaluate the occurrence of hot cracking based on simulation results and relevant criteria. The model was created stepwise in COMSOL Multiphysics, starting with the thermal model where heat conduction of solid and liquid phase was computed. Then the CFD model was created by involving the driving forces of liquid motion in the weld pool, i.e. natural convection and Marangoni effect. Lastly, the temperature profile calculated by the CFD model was loaded into the mechanical model for computation of thermal stress and strain. The mechanical results were required in criteria for measuring the susceptibility of hot cracking. The main findings include that Marangoni effect plays a dominant role in generating the fluid flow and convective heat flux in the weld pool, thus enhancing the heat dissipation and lowering temperature in the workpiece. By contrast, such temperature reduction caused by the air convection, radiation and natural convection is negligible. The welding track further from the clamped side experiences smaller transversal residual stress, but it does not necessarily suggest higher susceptibility to hot cracking according to the applied criteria. It can be concluded judging from current results that these first models of laser welding process work satisfactorily. There is still a work to do to obtain the full maturity of this model due to its limitation and some assumptions made for simplicity.Denna avhandling presenterar en modelleringsmetod för lasersvetsningsprocessen av aluminiumlegering ur termomekanisk synvinkel för att utvärdera förekomsten av het sprickbildning baserat på simuleringsresultat och relevanta kriterier. Modellen skapades stegvis i COMSOL Multiphysics, med början med den termiska modellen där värmeledning av fast och flytande fas beräknades. Sedan skapades CFD-modellen genom att involvera drivkrafterna för flytande rörelse i svetsbassängen, dvs. naturlig konvektion och Marangoni-effekt. Slutligen laddades temperaturprofilen beräknad av CFD-modellen in i den mekaniska modellen för beräkning av termisk stress och töjning. De mekaniska resultaten krävdes i kriterier för att mäta känsligheten för het sprickbildning. De viktigaste resultaten inkluderar att Marangoni-effekten spelar en dominerande roll när det gäller att generera vätskeflödet och konvektivt värmeflöde i svetsbassängen, vilket förbättrar värmeavledningen och sänker temperaturen i arbetsstycket. Däremot är sådan temperaturreduktion orsakad av luftkonvektion, strålning och naturlig konvektion försumbar. Svetsbanan längre från den fastspända sidan upplever mindre tvärgående restspänning, men det föreslår inte nödvändigtvis högre känslighet för hetsprickning enligt de tillämpade kriterierna. Man kan dra slutsatsen utifrån aktuella resultat att dessa första modeller av lasersvetsningsprocesser fungerar tillfredsställande. Det finns fortfarande ett arbete att göra för att få full mognad för denna modell på grund av dess begränsning och vissa antaganden för enkelhetens skull.
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Ragnarsson, Lars. "Formation of non-metallic inclusions and the possibility of their removal during ingot casting." Doctoral thesis, KTH, Mikro-modellering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12458.
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The present study was carried out to investigate the formation and evolution of non-metallic inclusions during ingot casting. Emphasize have been on understanding the types of inclusions formed and developed through the casting process and on the development of already existing inclusions carried over from the ladle during casting. Industrial experiments carried on at Uddeholm Tooling together with laboratory work and Computational Fluid Dynamics (CFD) simulations. Ingots of 5.8 tons have been sampled and the types of inclusions together with their distribution within the ingot have been characterized. Two new types of inclusions have been found. Type C1 is found originated from casting powder and in the size from a few μm to 30 μm. Type C2 is of macro inclusion type sizing up to 70 μm. The presence of C2 inclusions are few but very detrimental for the quality of the steel. Both types, C1 and C2 consist of alumina, indicating that reoxidation is the main reason for their existence. The protecting argon shroud has been studied by the use of a 1:1 scaled 2D model. Both flow pattern and oxygen measurement have been carried out. CFD has also been used as an auxiliary tool. It has been found that the oxygen pickup through argon gas shroud depends mostly on the distance between the ladle and the collar placed on top of runner. Further increase of gas flow rate above 2.5 m3.h-1 had very little effect on the oxygen distribution since both the flushing effect and the entraining effect with respect to oxygen are enhanced by further increase of inert gas flow rate. In the case of dual gas inlet, the flow in the shroud was found much less diffused compared with either vertical or horizontal injection system. The oxygen content in this arrangement was also greatly reduced. Studies of the runner after casting revealed a sparse non-metallic network structure around the periphery of the steel rod remained in the runner. The surface of the refractory had been severely attacked by the mechanical force from the streaming steel. The erosions of the centre stone and the end stone were on the other hand negligible. CFD calculations showed that the flow at those locations is almost stagnant. The surface of the refractory in contact with the steel was found to have an increased content of alumina. The source for the alumina could come from either exchange reaction of dissolved aluminium replaces the silica or reoxidation products origin from oxygen pick up during the transfer from the ladle to the vertical runner. Inclusions were also found entrapped in the steel refractory interface. It was also found that a formation of a liquid slag film as early as possible during casting would increase the possibility to remove inclusions and especially inclusions generated by the casting powder.QC 20100617
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Sivakumar, Krish. "CAD feature development and abstraction for process planning." Ohio : Ohio University, 1994. http://www.ohiolink.edu/etd/view.cgi?ohiou1180038784.
Full textBooks on the topic "CFD process model"
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service), SpringerLink (Online, ed. Innovation in product design: From CAD to virtual prototyping. London: Springer, 2011.
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Villagrán Munar, Edwin Andrés, Jorge Eliécer Jaramillo Noreña, Andrea Onelia Rodríguez Roa, Rommel Igor León Pacheco, and Marlón José Yacomelo Hernández. Invernadero bioclimático y modular para clima cálido: Diseño, construcción, operación y mantenimiento. Corporación Colombiana de Investigación Agropecuaria (Agrosavia), 2021. http://dx.doi.org/10.21930/agrosavia.manual.7404890.
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Esta obra tiene por objeto mostrar las características del montaje de un invernadero bioclimático ventilado de acuerdo con un diseño desarrollado el 2019 en el departamento de Magdalena, Colombia. Este diseño está basado en un modelo computacional de fluidos (CFD) 2-D para el desarrollo de simulaciones en estado estacionario, modelo que fue validado experimentalmente en el prototipo del invernadero real evaluado. Se destacan los siguientes contenidos de esta publicación: 1) descripción de la fase de diseño computacional apoyado en herramientas de modelado y simulación numérica, en el que se detallan preproceso, proceso y posproceso, 2) diseño arquitectónico, validación de las condiciones microclimáticas dentro de la estructura y método de medición de las variables asociadas al clima, 3) proceso de construcción, 4) presupuesto y 5) criterios para el mantenimiento. El invernadero bioclimático ventilado es una alternativa para intensificar la agricultura y mejorar la seguridad alimentaria en estas regiones de clima cálido, ya que está orientado a superar de manera eficiente las limitaciones usualmente impuestas por factores bióticos y abióticos que afectan la producción agrícola de estas zonas.
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Bordegoni, Monica, and Caterina Rizzi. Innovation in Product Design: From CAD to Virtual Prototyping. Springer, 2011.
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Bordegoni, Monica, and Caterina Rizzi. Innovation in Product Design: From CAD to Virtual Prototyping. Springer, 2014.
Find full textBook chapters on the topic "CFD process model"
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Philo, A. M., D. Butcher, Stuart Sillars, C. J. Sutcliffe, J. Sienz, S. G. R. Brown, and N. P. Lavery. "A Multiphase CFD Model for the Prediction of Particulate Accumulation in a Laser Powder Bed Fusion Process." In CFD Modeling and Simulation in Materials Processing 2018, 65–76. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-72059-3_7.
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Ishida, Fujimaro, Masanori Tsuji, Satoru Tanioka, Katsuhiro Tanaka, Shinichi Yoshimura, and Hidenori Suzuki. "Computational Fluid Dynamics for Cerebral Aneurysms in Clinical Settings." In Acta Neurochirurgica Supplement, 27–32. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63453-7_4.
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AbstractHemodynamics is thought to play an important role in the pathogenesis of cerebral aneurysms and recent development of computer technology makes it possible to simulate blood flow using high-resolution 3D images within several hours. A lot of studies of computational fluid dynamics (CFD) for cerebral aneurysms were reported; therefore, application of CFD for cerebral aneurysms in clinical settings is reviewed in this article.CFD for cerebral aneurysms using a patient-specific geometry model was first reported in 2003 and it has been revealing that hemodynamics brings a certain contribution to understanding aneurysm pathology, including initiation, growth and rupture. Based on the knowledge of the state-of-the-art techniques, this review treats the decision-making process for using CFD in several clinical settings. We introduce our CFD procedure using digital imaging and communication in medicine (DICOM) datasets of 3D CT angiography or 3D rotational angiography. In addition, we review rupture status, hyperplastic remodeling of aneurysm wall, and recurrence of coiled aneurysms using the hemodynamic parameters such as wall shear stress (WSS), oscillatory shear index (OSI), aneurysmal inflow rate coefficient (AIRC), and residual flow volume (RFV).
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Rodi, Wolfgang. "The ERCOFTAC Knowledge Base Wiki - An Aid for Validating CFD Models." In Process and Plant Safety, 179–87. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527645725.ch11.
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Gouvalias, G., N. C. Markatos, J. Panagopoulos, M. J. Tierney, S. Huberson, and G. Zhong. "Advanced Flow Modelling for Industrial Applications — CFD Models of Adsorbers." In Energy Efficiency in Process Technology, 374–87. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1454-7_34.
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Grabowski, H., R. S. Lossack, and C. Weis. "A Design Process Model based on Design Working Spaces." In Knowledge Intensive CAD, 244–62. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-0-387-34930-5_16.
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Godec, Damir, Ana Pilipović, and Tomislav Breški. "General Process Workflow in Additive Manufacturing." In A Guide to Additive Manufacturing, 45–57. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-05863-9_2.
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AbstractIn this chapter, general workflow in Additive Manufacturing process is shown, from preprocessing activities that include preparing appropriate CAD model, selecting required STL file resolution, up to setting processing parameters for AM process.
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Schatzmann, Michael, and Bernd Leitl. "Validation of CFD Models for the Prediction of Gas Dispersion in Urban and Industrial Environments." In Process and Plant Safety, 213–32. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2012. http://dx.doi.org/10.1002/9783527645725.ch13.
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King, Robin G. "A Structural Model of Creative Process for Improved Interface Design." In Advances in CAD/CAM Workstations, 127–43. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4613-2273-3_13.
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Lei, Bangyu, Toshiharu Taura, and Jun Numata. "Representing the Collaborative Design Process: A Product Model-Oriented Approach." In Advances in Formal Design Methods for CAD, 267–85. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-0-387-34925-1_15.
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Weber, Moritz, and Reiner Anderl. "Ontology-Based Calculation of Complexity Metrics for Components in CAD Systems." In Lecture Notes in Mechanical Engineering, 3–11. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77256-7_1.
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AbstractThe high complexity of assemblies and components in Computer-Aided Design (CAD) leads to a high effort in the maintenance of the models and increases the time required for adjustments. Metrics indicating the complexity of a CAD Model can help to reduce it by showing the results of changes. This paper describes a concept to calculate metrics aiming to describe the extent of complexity of components in CAD systems based on an ontology-based representation in a first step. The representation is initially generated from CAD models using an automated process. This includes both a boundary representation and the history of the feature-based design. Thus, the design strategy also contributes to measuring the complexity of the component so that the same shape can lead to different complexity metrics. Semantic rules are applied to find patterns of the design and to identify and evaluate various strategies. Different metrics are proposed to indicate the particular influence factors of complexity and a single measure for the overall complexity. Furthermore, the influencing factors can also be used to allow the designer to see how to reduce the complexity of the component or assembly.
Conference papers on the topic "CFD process model"
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Ruiz, O. E. "CFD Model of the Thermal Inkjet Droplet Ejection Process." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32427.
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Numerical simulations of the thermal inkjet (TIJ) droplet ejection process are performed. The computational approach is based on a volume of fluid (VOF) formulation. This method allows determining the coupled flow and thermal fields in the firing chamber in addition to the phase change processes that take place during the drive bubble formation, expansion, and collapse. The drive bubble pressure is a result of the phase change heat transfer during the heating pulse and is not imposed by a pressure heuristic approach. A commercially available TIJ architecture was chosen as a baseline to assess the computational model predictions of ejected droplet volume and droplet velocity during a firing cycle. These computational model predictions were compared to experimental results demonstrating an excellent agreement. The transient histories of pressure in the vapor bubble, temperature, and heat transfer rate to the fluid are analyzed to explain some of the relevant physical processes observed.
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Conti, Paolo, and Marco Argento. "CFD Integration Into Design Process of Motorcycles." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95462.
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This work displays an integrated approach — based on both experimental and numerical analyses (CFD) — to scooter design. In the last decade the market of maxi scooters is continually increasing. Any constructor must develop new models, new design, new concepts. Due to this fast evolution, the possibility to cope aesthetics and functionality, at each step design process, may be a crucial aspects. The purpose of this work is the development of a method to take into account aerodynamic behaviour of a scooter depending on its external geometry. The analysis is mainly directed to investigate stability, safety and comfort aspects rather than aerodynamic fairness. The paper presents a methodology to integrate in the conceptual design process many aerodynamic aspects. First a parametric simplified model was created and investigated. This model is composed of few plane panels which outline a commercial scooter. The scope was the validation of the analysis method through an experimental campaign in a wind tunnel. Then, the methodology was applied to a real scooter. As a conclusion the paper points out the importance of embedding aerodynamic skills into the very initial conceptual design of a scooter, and the method proposed tries to answer to this need.
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Pietrykowski, Konrad. "The CFD Model of the Combustion Process in a Radial Engine." In SAE 2014 International Powertrain, Fuels & Lubricants Meeting. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2014. http://dx.doi.org/10.4271/2014-01-2578.
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Epelbaum, Greg, and Hanwei Zhang. "New Development in EfW Boiler Process Modeling: Fully Integrated CFD Model." In 15th Annual North American Waste-to-Energy Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/nawtec15-3206.
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This paper focuses on a Computational Fluid Dynamics (CFD) application to Energy-from-Waste (EfW) boiler systems, which are much smaller than utility boilers, but typically have more complicated design and performance issues due to the nature of their fuel: municipal solid waste (MSW). The majority of the commercially available CFD software packages have impressive capabilities in homogeneous flow modeling, which make them very suitable for gas fired boilers and with some reasonable simplifications to oil and pulverized coal fired boilers. But this is not the case for EfW boilers, especially mass-burn technology, where MSW combustion on the grate is the “heart” of the process. These boilers have two interacting phases: MSW burning on the grate and combustion products with entrained fly ash particles above the grate. This challenge has been recognized from the very first applications of CFD modeling in the EfW industry. This paper describes several approaches to numeric modeling of MSW boilers. In the most successful cases, two different models have been built: one for the grate combustion and another for the homogeneous gas flow, with back-and-forth iterations between these two models. Such an approach has given Covanta Energy (Covanta) a good start in its CFD modeling program. A number of models have been built, tested and validated, resulting in several successful project executions. However, some serious limitations have been found in this approach as explained in this paper. Recognizing these deficiencies, Covanta has recently made a new significant step in its CFD development program by creating an innovative, fully integrated CFD model that comprises solid fuel combustion on the grate, gaseous phase interactions above the grate, and the rest of the boiler. While this integrated model and its validation are still in progress, Covanta is moving forward on its application to on-going projects.
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Martin, Richard A., Tim Thompson, Naseem Ansari, and Chokri Guetari. "IceCube CFD Drilling Model." In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98042.
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A numerical model of a hot water drill used to produce deep holes in clear ice at the South Pole for the IceCube neutrino observatory program scheduled for completion in 2010 has been developed. The model was built using the ANSYS commercial computational fluid dynamics (CFD) code, ANSYS CFX. This drill model is helping us to understand the water/ice melting process near the bottom of the drill hole, and to evaluate the influence of nozzle size, spray angle, water flow rate, and water temperature on the drill hole shape, and on drilling speed. The basis for the model is ANSYS CFX, which has multi-phase, conjugate heat transfer capabilities. The model utilizes a multi-phase approach, and simulates motion of the drill with respect to the ice. The sensitivity of model predictions to mesh resolution, turbulence model, and interfacial heat transfer coefficients, area, and drag coefficient was studied, and the results were used to determine preferred values in each case. This multi-phase model was selected after evaluating an equilibrium model and obtaining results showing not completely satisfactory comparisons to experimental data from the South Pole. Computations at a drill depth of 1292 m allowed validation of code results using actual field data obtained during the 2004–2005 IceCube drilling season at Antarctica. A series of steady-state runs using two drill sizes, two drill speeds, and one spray angle were performed for conditions at 1292 m to determine if a smaller nozzle orifice would enable faster drilling, preferably by a factor of two. The model predicted a drill hole diameter of from 18 in to 25 in and an up-flow water temperature of from 20°C to 28°C. The drill hole diameter is consistent with values measured at the IceCube site, but the water temperature is about 10°C low. No evidence of the nozzle tip impacting the bottom of the hole was found in the drill speed range 3.5 ft/min to 7 ft/min. A nozzle spray angle of 25 degrees was found to make little difference in hole depth or diameter. Reducing the nozzle diameter from 1 in to 0.75 in at the same water volumetric flow rate resulted in an increase in the drill hole depth by from 16% to 20%. The latter result implies that faster drilling is expected when using a smaller size orifice with zero degree spray angle. The IceCube drill model is now available to determine the effects of key variables, to evaluate the performance of new nozzle designs, and to specify drill speed versus depth. Recommendations specific to faster drilling speeds resulted in a near doubling of actual speed during the 2005–2006 season at the South Pole.
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Giorges, Aklilu T. G., and John A. Pierson. "Modeling and CFD Simulation of Membrane Flow Process." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53530.
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In the processing industries several membrane technologies are used to separate and concentrate various fluid stream where the concentrate or/filtrate has high value products. Nevertheless, pore blocking is one of the major factors determining the applicability, efficiency and performance of the membrane filtration and separation system. Inside and outside membrane pore blockage leads to concentration polarization and cake buildup that reduces the flux rate and increases losses in system efficiency. Several experimental and theoretical works exist that describe the pore flow and blocking process. However, a limited amount of published work integrates the pore blocking with computational fluid dynamics (CFD). The change in the fluid stream and membrane characteristics during the process are the major challenges in CFD modeling. This paper presents the initial simulations of two-dimensional CFD models that directly model the actual micro pore flow and the porous medium flow (Darcy flow). Various pressure and pore sizes (porosity and permeability) were simulated. For the first model, pore flow model, simplified two-dimensional micro pores were modeled and the continuity and Navier-Stokes equations were solved in all regions including pores. Appling various inlet pressures, the velocity and pressure in all fluid regions are simulated. In second model, the membrane region is modeled as porous medium and the flow field is simulated by using porous medium characteristics. The porous medium characteristics, porosity and permeability, were estimated from pore flow average outlet velocity. The result indicates that both models with equivalent values can be used to predict the overall flow fields. However, both models have to overcome challenges to be widely used. With the direct pore flow (pores flow) simulation, mesh generation becomes a challenge since the membrane pores are very small as compared to the inlet and outlet regions. The pore flow simulation results indicate that CFD can be used to understand the membrane flow characteristics and fluid mechanics. It also can be used to design and / or select a membrane system. For the simulation of membrane as porous medium, the detail of flow through the porous medium including the inlet and outlet effects becomes obscured. However, the system overall performance can be simulated using CFD model for porous medium.
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Bialy, Michal, Miroslaw Wendeker, Pawel Magryta, Zbigniew Czyz, and Rafal Sochaczewski. "CFD Model of the Mixture Formation Process of the CNG Direct Injection Engine." In SAE 2014 International Powertrain, Fuels & Lubricants Meeting. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2014. http://dx.doi.org/10.4271/2014-01-2575.
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Thompson, Julia, Dr Michael Donn, and Dr George Baird. "The Calibration Process for a CFD Simulated Model of a Naturally Ventilated Auditorium." In 2017 Building Simulation Conference. IBPSA, 2017. http://dx.doi.org/10.26868/25222708.2017.752.
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Kinzel, Michael P., Jules W. Lindau, and Robert F. Kunz. "A Unified Homogenous Multiphase CFD Model for Cavitation." In ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69363.
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The present paper aims to close the gap on the understanding of cavitation model performance with respect to their inherent empirical constants. We first unify several cavitation models, providing a consistent framework for model comparison. Analytical methods are developed to directly compare cavitation models to the Rayleigh Plesset equation. The process is used to (1) develop a method to compare and equivocate models analytically, (2) develop a method to directly assess changes in the cavitation model with respect to bubble dynamics, and (3) provide insight into model improvement. The results identify general physical modeling issues and show that, if the empirical constants are correctly adjusted, the cavitation models yield similar results.
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Kawanabe, Hiroshi, Yusuke Naito, and Takuji Ishiyama. "Numerical Analysis for Mixing Process of High-speed Unsteady Jets Using PDF-CFD Model." In SAE 2006 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2006. http://dx.doi.org/10.4271/2006-01-1193.
Full textReports on the topic "CFD process model"
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Pullammanappallil, Pratap, Haim Kalman, and Jennifer Curtis. Investigation of particulate flow behavior in a continuous, high solids, leach-bed biogasification system. United States Department of Agriculture, January 2015. http://dx.doi.org/10.32747/2015.7600038.bard.
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Recent concerns regarding global warming and energy security have accelerated research and developmental efforts to produce biofuels from agricultural and forestry residues, and energy crops. Anaerobic digestion is a promising process for producing biogas-biofuel from biomass feedstocks. However, there is a need for new reactor designs and operating considerations to process fibrous biomass feedstocks. In this research project, the multiphase flow behavior of biomass particles was investigated. The objective was accomplished through both simulation and experimentation. The simulations included both particle-level and bulk flow simulations. Successful computational fluid dynamics (CFD) simulation of multiphase flow in the digester is dependent on the accuracy of constitutive models which describe (1) the particle phase stress due to particle interactions, (2) the particle phase dissipation due to inelastic interactions between particles and (3) the drag force between the fibres and the digester fluid. Discrete Element Method (DEM) simulations of Homogeneous Cooling Systems (HCS) were used to develop a particle phase dissipation rate model for non-spherical particle systems that was incorporated in a two-fluid CFDmultiphase flow model framework. Two types of frictionless, elongated particle models were compared in the HCS simulations: glued-sphere and true cylinder. A new model for drag for elongated fibres was developed which depends on Reynolds number, solids fraction, and fibre aspect ratio. Schulze shear test results could be used to calibrate particle-particle friction for DEM simulations. Several experimental measurements were taken for biomass particles like olive pulp, orange peels, wheat straw, semolina, and wheat grains. Using a compression tester, the breakage force, breakage energy, yield force, elastic stiffness and Young’s modulus were measured. Measurements were made in a shear tester to determine unconfined yield stress, major principal stress, effective angle of internal friction and internal friction angle. A liquid fludized bed system was used to determine critical velocity of fluidization for these materials. Transport measurements for pneumatic conveying were also assessed. Anaerobic digestion experiments were conducted using orange peel waste, olive pulp and wheat straw. Orange peel waste and olive pulp could be anaerobically digested to produce high methane yields. Wheat straw was not digestible. In a packed bed reactor, anaerobic digestion was not initiated above bulk densities of 100 kg/m³ for peel waste and 75 kg/m³ for olive pulp. Interestingly, after the digestion has been initiated and balanced methanogenesis established, the decomposing biomass could be packed to higher densities and successfully digested. These observations provided useful insights for high throughput reactor designs. Another outcome from this project was the development of low cost devices to measure methane content of biogas for off-line (US$37), field (US$50), and online (US$107) applications.
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Kunkel, Robert W., Anderson Jr., and John R. Conversion Process of a Ballistic Research Laboratory Computer-Aided Design (BRL-CAD) Model to a Panelized Surface Model (PSM). Fort Belvoir, VA: Defense Technical Information Center, February 2001. http://dx.doi.org/10.21236/ada392174.
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Ross, Andrew, David Johnson, Hai Le, Danny Griffin, Carl Mudd, and David Dawson. USACE Advanced Modeling Object Standard : Release 1.0. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/42152.
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The U.S. Army Corps of Engineers (USACE) Advanced Modeling Object Standard (AMOS) has been developed by the CAD/BIM Technology Center for Facilities, Infrastructure, and Environment to establish standards for support of the Advanced Modeling process within the Department of Defense (DoD) and the Federal Government. The critical component of Advanced Modeling is the objects themselves- and either make the modeling process more difficult or more successful. This manual is part of an initiative to develop a nonproprietary Advanced Modeling standard that incorporates both vertical construction and horizontal construction objects that will address the entire life cycle of facilities within the DoD. The material addressed in this USACE Advanced Modeling Object Standard includes a classification organization that is needed to identify models for specific use cases. Compliance with this standard will allow users to know whether the object model they are getting is graphically well developed but data poor or if it does have the data needed for creating contract documents. This capability will greatly reduce the designers’ efforts to either build an object or search/find/edit an object necessary for the development of their project. Considering that an advanced model may contain hundreds of objects this would represent a huge time savings and improve the modeling process.
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Smugeresky, J. E., D. M. Keicher, J. A. Romero, M. L. Griffith, and L. D. Harwell. Using the Laser Engineered Net Shaping (LENS{trademark}) process to produce complex components from a CAD solid model. Office of Scientific and Technical Information (OSTI), August 1997. http://dx.doi.org/10.2172/554822.
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de Kemp, E. A., H. A. J. Russell, B. Brodaric, D. B. Snyder, M. J. Hillier, M. St-Onge, C. Harrison, et al. Initiating transformative geoscience practice at the Geological Survey of Canada: Canada in 3D. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/331097.
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Application of 3D technologies to the wide range of Geosciences knowledge domains is well underway. These have been operationalized in workflows of the hydrocarbon sector for a half-century, and now in mining for over two decades. In Geosciences, algorithms, structured workflows and data integration strategies can support compelling Earth models, however challenges remain to meet the standards of geological plausibility required for most geoscientific studies. There is also missing links in the institutional information infrastructure supporting operational multi-scale 3D data and model development. Canada in 3D (C3D) is a vision and road map for transforming the Geological Survey of Canada's (GSC) work practice by leveraging emerging 3D technologies. Primarily the transformation from 2D geological mapping, to a well-structured 3D modelling practice that is both data-driven and knowledge-driven. It is tempting to imagine that advanced 3D computational methods, coupled with Artificial Intelligence and Big Data tools will automate the bulk of this process. To effectively apply these methods there is a need, however, for data to be in a well-organized, classified, georeferenced (3D) format embedded with key information, such as spatial-temporal relations, and earth process knowledge. Another key challenge for C3D is the relative infancy of 3D geoscience technologies for geological inference and 3D modelling using sparse and heterogeneous regional geoscience information, while preserving the insights and expertise of geoscientists maintaining scientific integrity of digital products. In most geological surveys, there remains considerable educational and operational challenges to achieve this balance of digital automation and expert knowledge. Emerging from the last two decades of research are more efficient workflows, transitioning from cumbersome, explicit (manual) to reproducible implicit semi-automated methods. They are characterized by integrated and iterative, forward and reverse geophysical modelling, coupled with stratigraphic and structural approaches. The full impact of research and development with these 3D tools, geophysical-geological integration and simulation approaches is perhaps unpredictable, but the expectation is that they will produce predictive, instructive models of Canada's geology that will be used to educate, prioritize and influence sustainable policy for stewarding our natural resources. On the horizon are 3D geological modelling methods spanning the gulf between local and frontier or green-fields, as well as deep crustal characterization. These are key components of mineral systems understanding, integrated and coupled hydrological modelling and energy transition applications, e.g. carbon sequestration, in-situ hydrogen mining, and geothermal exploration. Presented are some case study examples at a range of scales from our efforts in C3D.
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Shalhout, Shalhout Zaki. A search for the Standard Model Higgs boson in the process ZH → ℓ+ℓ-b$\bar{b}$ in 4.1 fb-1 of CDF II data. Office of Scientific and Technical Information (OSTI), May 2010. http://dx.doi.org/10.2172/985419.
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Allgood, G. O., W. B. Dress, and S. W. Kercel. Developing a CD-CBM Anticipatory Approach for Cavitation - Defining a Model-Based Descriptor Consistent Across Processes, Phase 1 Final Report Context-Dependent Prognostics and Health Assessment: A New Paradigm for Condition-based Maintenance SBIR Topic No. N98-114. Office of Scientific and Technical Information (OSTI), June 1999. http://dx.doi.org/10.2172/7818.
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A SURROGATE MODEL TO ESTIMATE THE AXIAL COMPRESSIVE CAPACITY OF COLD-FORMED STEEL OPEN BUILT-UP SECTIONS. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.316.
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This paper proposed a surrogate model to simplify the process of estimating the axial compressive capacity of cold-formed steel (CFS) open built-up sections composed of lipped channels with different section sizes, thickness, length, and connector spacing. The surrogate model was developed based on the current design methods, i.e., the Effective Width Method (EWM) and Direct Strength Method (DSM), which are codified in the North American Specification AISI S100-16. This new model features two surface regression equations with a boundary inequality criteria, anchored on two important parameters, i.e., modified slenderness ratio, (KL/r)m and minimum thickness-to-width ratio (t/w)min of the built-up sections. The model was validated with 1089 sets of the experimental results data collected from previous research tested on the axial capacity of CFS open built-up sections with the different design configurations. The proposed surrogate model is aimed to simplify the design process among practising engineers for a quick preliminary calculation of the axial compressive capacity of these new CFS open built-up sections.
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Payment Systems Report - June of 2020. Banco de la República de Colombia, February 2021. http://dx.doi.org/10.32468/rept-sist-pag.eng.2020.
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With its annual Payment Systems Report, Banco de la República offers a complete overview of the infrastructure of Colombia’s financial market. Each edition of the report has four objectives: 1) to publicize a consolidated account of how the figures for payment infrastructures have evolved with respect to both financial assets and goods and services; 2) to summarize the issues that are being debated internationally and are of interest to the industry that provides payment clearing and settlement services; 3) to offer the public an explanation of the ideas and concepts behind retail-value payment processes and the trends in retail payments within the circuit of individuals and companies; and 4) to familiarize the public, the industry, and all other financial authorities with the methodological progress that has been achieved through applied research to analyze the stability of payment systems. This edition introduces changes that have been made in the structure of the report, which are intended to make it easier and more enjoyable to read. The initial sections in this edition, which is the eleventh, contain an analysis of the statistics on the evolution and performance of financial market infrastructures. These are understood as multilateral systems wherein the participating entities clear, settle and register payments, securities, derivatives and other financial assets. The large-value payment system (CUD) saw less momentum in 2019 than it did the year before, mainly because of a decline in the amount of secondary market operations for government bonds, both in cash and sell/buy-backs, which was offset by an increase in operations with collective investment funds (CIFs) and Banco de la República’s operations to increase the money supply (repos). Consequently, the Central Securities Depository (DCV) registered less activity, due to fewer negotiations on the secondary market for public debt. This trend was also observed in the private debt market, as evidenced by the decline in the average amounts cleared and settled through the Central Securities Depository of Colombia (Deceval) and in the value of operations with financial derivatives cleared and settled through the Central Counterparty of Colombia (CRCC). Section three offers a comprehensive look at the market for retail-value payments; that is, transactions made by individuals and companies. During 2019, electronic transfers increased, and payments made with debit and credit cards continued to trend upward. In contrast, payments by check continued to decline, although the average daily value was almost four times the value of debit and credit card purchases. The same section contains the results of the fourth survey on how the use of retail-value payment instruments (for usual payments) is perceived. Conducted at the end of 2019, the main purpose of the survey was to identify the availability of these payment instruments, the public’s preferences for them, and their acceptance by merchants. It is worth noting that cash continues to be the instrument most used by the population for usual monthly payments (88.1% with respect to the number of payments and 87.4% in value). However, its use in terms of value has declined, having registered 89.6% in the 2017 survey. In turn, the level of acceptance by merchants of payment instruments other than cash is 14.1% for debit cards, 13.4% for credit cards, 8.2% for electronic transfers of funds and 1.8% for checks. The main reason for the use of cash is the absence of point-of-sale terminals at commercial establishments. Considering that the retail-payment market worldwide is influenced by constant innovation in payment services, by the modernization of clearing and settlement systems, and by the efforts of regulators to redefine the payment industry for the future, these trends are addressed in the fourth section of the report. There is an account of how innovations in technology-based financial payment services have developed, and it shows that while this topic is not new, it has evolved, particularly in terms of origin and vocation. One of the boxes that accompanies the fourth section deals with certain payment aspects of open banking and international experience in that regard, which has given the customers of a financial entity sovereignty over their data, allowing them, under transparent and secure conditions, to authorize a third party, other than their financial entity, to request information on their accounts with financial entities, thus enabling the third party to offer various financial services or initiate payments. Innovation also has sparked interest among international organizations, central banks, and research groups concerning the creation of digital currencies. Accordingly, the last box deals with the recent international debate on issuance of central bank digital currencies. In terms of the methodological progress that has been made, it is important to underscore the work that has been done on the role of central counterparties (CCPs) in mitigating liquidity and counterparty risk. The fifth section of the report offers an explanation of a document in which the work of CCPs in financial markets is analyzed and corroborated through an exercise that was built around the Central Counterparty of Colombia (CRCC) in the Colombian market for non-delivery peso-dollar forward exchange transactions, using the methodology of network topology. The results provide empirical support for the different theoretical models developed to study the effect of CCPs on financial markets. Finally, the results of research using artificial intelligence with information from the large-value payment system are presented. Based on the payments made among financial institutions in the large-value payment system, a methodology is used to compare different payment networks, as well as to determine which ones can be considered abnormal. The methodology shows signs that indicate when a network moves away from its historical trend, so it can be studied and monitored. A methodology similar to the one applied to classify images is used to make this comparison, the idea being to extract the main characteristics of the networks and use them as a parameter for comparison. Juan José Echavarría Governor