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Halas, Dragan, Oskar Bera, Radovan Omorjan, Aleksandar Rajic i Danijela Jasin. "Analysis of new forms of orifice plates using computational fluid dynamics". Chemical Industry 73, nr 5 (2019): 311–23. http://dx.doi.org/10.2298/hemind190722030h.
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In many technologies, such as process industry or water supply, there is a need to measure fluid flowrates. Orifice plates are the most common instruments for measuring the fluid flowrate through pipelines due to their many advantages. On the other side, their use increases operating costs of industrial plants and pipelines. In this work, three new forms of orifice plates were designed and tested. These new forms and one standard, which served as a reference, were designed by using the SolidWorks software package. The aim of the new designs was energy savings, and consequently reduction of operating costs. Energy savings can be achieved by such a design, which decreases the orifice plate resistance an element of the pipeline. This was achieved by increasing the open part of the orifice plate permitting the fluid flow. CAD models of orifice plates were transferred to STL files that were further used for CFD simulation as well as 3D printing of experimental replicas. According to the proposed algorithm, the new designs were tested by CFD simulation performed in the COMSOL Multiphysics software package, by using a finite-difference method. Equations used were based on the Reynolds form of Navier-Stokes equations (RANS, Reynolds-averaged Navier-Stokes), and the continuity equation for incompressible fluids. Next, as we have proposed in our algorithm of development of new orifice plate designs, experimental orifice plates were made by using 3D printing technology and FDM (Fused Deposition Modeling) procedure and tested at laboratory conditions. The results of laboratory tests were compared with the results of CFD simulation. A considerable amount of energy saving was indicated, which was achieved already by the first of the three new orifice plate forms (V1) as compared to the reference (V0). For the other two proposed forms, the effect of energy savings was considerably lower. By using CFD simulation, data can be obtained based on which a decision can be made whether the new shape of the measuring device should be corrected or is appropriate for further laboratory tests. Based on the presented results it can be concluded that the proposed testing algorithm proved useful in designing new forms of orifice plates.
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Oberkampf, William L., Timothy G. Trucano i Charles Hirsch. "Verification, validation, and predictive capability in computational engineering and physics". Applied Mechanics Reviews 57, nr 5 (1.09.2004): 345–84. http://dx.doi.org/10.1115/1.1767847.
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Developers of computer codes, analysts who use the codes, and decision makers who rely on the results of the analyses face a critical question: How should confidence in modeling and simulation be critically assessed? Verification and validation (V&V) of computational simulations are the primary methods for building and quantifying this confidence. Briefly, verification is the assessment of the accuracy of the solution to a computational model. Validation is the assessment of the accuracy of a computational simulation by comparison with experimental data. In verification, the relationship of the simulation to the real world is not an issue. In validation, the relationship between computation and the real world, ie, experimental data, is the issue. This paper presents our viewpoint of the state of the art in V&V in computational physics. (In this paper we refer to all fields of computational engineering and physics, eg, computational fluid dynamics, computational solid mechanics, structural dynamics, shock wave physics, computational chemistry, etc, as computational physics.) We describe our view of the framework in which predictive capability relies on V&V, as well as other factors that affect predictive capability. Our opinions about the research needs and management issues in V&V are very practical: What methods and techniques need to be developed and what changes in the views of management need to occur to increase the usefulness, reliability, and impact of computational physics for decision making about engineering systems? We review the state of the art in V&V over a wide range of topics, for example, prioritization of V&V activities using the Phenomena Identification and Ranking Table (PIRT), code verification, software quality assurance (SQA), numerical error estimation, hierarchical experiments for validation, characteristics of validation experiments, the need to perform nondeterministic computational simulations in comparisons with experimental data, and validation metrics. We then provide an extensive discussion of V&V research and implementation issues that we believe must be addressed for V&V to be more effective in improving confidence in computational predictive capability. Some of the research topics addressed are development of improved procedures for the use of the PIRT for prioritizing V&V activities, the method of manufactured solutions for code verification, development and use of hierarchical validation diagrams, and the construction and use of validation metrics incorporating statistical measures. Some of the implementation topics addressed are the needed management initiatives to better align and team computationalists and experimentalists in conducting validation activities, the perspective of commercial software companies, the key role of analysts and decision makers as code customers, obstacles to the improved effectiveness of V&V, effects of cost and schedule constraints on practical applications in industrial settings, and the role of engineering standards committees in documenting best practices for V&V. There are 207 references cited in this review article.
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Schultz, Richard, Edwin Harvego i Ryan Crane. "Development of a Standard for Verification and Validation of Software Used to Calculate Nuclear System Thermal Fluids Behavior." Mechanical Engineering 132, nr 05 (1.05.2010): 56–57. http://dx.doi.org/10.1115/1.2010-may-6.
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This article focuses on the need for development of a standard for verification and validation (V&V) of software used to calculate nuclear system thermal fluids behavior. The V&V 30 Committee has been established to develop an ASME standard for verification and validation of computational fluid dynamics and system analysis software that will be used in the design and analysis of advanced nuclear reactor systems, with an initial focus on high-temperature gas-cooled reactors. The processes and procedures that will be addressed in the new standard will be used in the design and analysis of advanced reactor systems to be licensed in the United States. Recently, the V&V20 standard was released: Standard for Verification and Validation (V&V) in Computational Fluid Dynamics and Heat Transfer. Because of similarities in the standards being developed by the V&V20 and V&V30 Committees, it is important to define the relationship between the work embodied in the V&V20 Standard versus the work that will be forthcoming in the V&V30 Standard, as noted in the V&V20 Standard.
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Baburic, Mario, Alexandre Raulot i Neven Duic. "Implementation of discrete transfer radiation method into swift computational fluid dynamics code". Thermal Science 8, nr 1 (2004): 19–28. http://dx.doi.org/10.2298/tsci0401019b.
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The Computational Fluid Dynamics (CFD) has developed into a powerful tool widely used in science, technology and industrial design applications, when ever fluid flow, heat transfer, combustion, or other complicated physical processes, are involved. During decades of development of CFD codes scientists were writing their own codes, that had to include not only the model of processes that were of interest, but also a whole spectrum of necessary CFD procedures, numerical techniques, pre-processing and post-processing. That has arrested much of the scientist effort in work that has been copied many times over, and was not actually producing the added value. The arrival of commercial CFD codes brought relief to many engineers that could now use the user-function approach for mod el ling purposes, en trusting the application to do the rest of the work. This pa per shows the implementation of Discrete Transfer Radiation Method into AVL?s commercial CFD code SWIFT with the help of user defined functions. Few standard verification test cases were per formed first, and in order to check the implementation of the radiation method it self, where the comparisons with available analytic solution could be performed. After wards, the validation was done by simulating the combustion in the experimental furnace at IJmuiden (Netherlands), for which the experimental measurements were available. The importance of radiation prediction in such real-size furnaces is proved again to be substantial, where radiation itself takes the major fraction of over all heat transfer. The oil-combustion model used in simulations was the semi-empirical one that has been developed at the Power Engineering Department, and which is suit able for a wide range of typical oil flames.
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Liplenko, M. A., A. N. Borodenko i G. V. Mosolov. "The calculation of loads on buildings and structures caused by outdoor explosions of the fuel-air mixture". Pozharovzryvobezopasnost/Fire and Explosion Safety 31, nr 1 (17.03.2022): 88–98. http://dx.doi.org/10.22227/0869-7493.2022.31.01.88-98.
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Introduction. An important engineering task, to be solved in the process of designing buildings and structures for hazardous industrial facilities, is to determine values of loads caused by outdoor explosions of the fuel-air mixture. Nowadays software packages, that use the computational fluid dynamics (CFD) approach, are widely applied in the design practice to assess various effects on building structures. In this regard, it is necessary to develop a load calculation method, that employs numerical simulation, and verify it in comparison with the experimental data.Goals and objectives. The purpose of this work is to use the method of computational fluid dynamics to analyze external sympathetic detonation loads on various types of buildings and structures.The body of the article. The article addresses the “compressed balloon” method used to analyze loads, caused by outdoor explosions of gas. Dependencies, proposed in the article, are needed to set the input data and make numerical calculations using the computational fluid dynamics (CFD) technique. The numerical modeling of various experiments in the ANSYS Fluent software package was conducted. The authors compared the results of numerical modeling and standard engineering methods with various experiments to assess the accuracy of the “compressed balloon” method used to analyze an outdoor detonation explosion.Conclusions. The authors have proven the qualitative and quantitative convergence of the numerical model of blast wave propagation and the experimental data. This calculation method allows to accurately apply the pressure profile to any surface of a building or structure in the course of an outdoor detonation explosion and estimate the bearing capacity of building structures. The proposed method can be used in the design of buildings or structures that feature various configurations.
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Bao, Hai Tao. "Transient Numerical of Piston Wind in Subway Station". Applied Mechanics and Materials 644-650 (wrzesień 2014): 467–70. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.467.
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Computational Fluid Dynamics (CFD) is used for the investigation of the piston wind. The Navier-Stokes (N-S) equations and standard turbulence model were applied to set up the model. The train transient aerodynamic characteristic has been research during the crossing process. The simulation results are trustworthy and numerical simulation of piston wind is feasible using dynamic grid in CFD software, which provides the basis for the virtual design of piston wind. It is significant importance for further studying the structure of train, shorten its development and guiding significance for practical application.
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Ramanath, H. S., i C. K. Chua. "Application of rapid prototyping and computational fluid dynamics in the development of water flow regulating valves". International Journal of Advanced Manufacturing Technology 30, nr 9-10 (8.12.2005): 828–35. http://dx.doi.org/10.1007/s00170-005-0119-5.
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Okafor, Chinedum Vincent, U. John Ezeokonkwo, Dominic Anosike Obodoh i Peter Ogunoh. "Atmospheric Boundary Layer Simulation Using Wall Function Approach in OpenFoam CFD Software". European Journal of Engineering Research and Science 3, nr 2 (6.02.2018): 1. http://dx.doi.org/10.24018/ejers.2018.3.2.597.
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The significant development in computer resources in the past years has increased the awareness of computational fluid dynamics as an alternative tool to the costly wind tunnel testing. The paper presented the application of CFD technique for a case study in simulating an existing site together with a proposed building and the local landscape. Finally, the limitations of the code analytical methods to the CFD method for wind around building analysis were discussed. From the result obtained, it was observed that the British standard (BS6399-2:1997) procedures are based on general assumptions and are not always conservative and do not provide accurate wind load results due to complex geometrical shapes, aerodynamic interaction, torsion, and load combinations as discussed in section VII.
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Okafor, Chinedum Vincent, U. John Ezeokonkwo, Dominic Anosike Obodoh i Peter Ogunoh. "Atmospheric Boundary Layer Simulation Using Wall Function Approach in OpenFoam CFD Software". European Journal of Engineering and Technology Research 3, nr 2 (6.02.2018): 1–6. http://dx.doi.org/10.24018/ejeng.2018.3.2.597.
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The significant development in computer resources in the past years has increased the awareness of computational fluid dynamics as an alternative tool to the costly wind tunnel testing. The paper presented the application of CFD technique for a case study in simulating an existing site together with a proposed building and the local landscape. Finally, the limitations of the code analytical methods to the CFD method for wind around building analysis were discussed. From the result obtained, it was observed that the British standard (BS6399-2:1997) procedures are based on general assumptions and are not always conservative and do not provide accurate wind load results due to complex geometrical shapes, aerodynamic interaction, torsion, and load combinations as discussed in section VII.
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Salakhov, Rishat, Andrey Ermakov i Elvira Gabdulkhakova. "Numerical and Experimental Study of the Impeller of a Liquid Pump of a Truck Cooling System and the Development of a New Open-Type Impeller". Tehnički glasnik 14, nr 2 (11.06.2020): 135–42. http://dx.doi.org/10.31803/tg-20200309115417.
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Typically, closed-type impellers are more efficient than open-type impellers, but in the manufacture of closed-type impellers, cost of wheels is higher. This paper describes the development of cost-effective and simple impeller wheel for a fluid pump in the truck cooling system. To perform this task, the numerical computations of a standard impeller wheel were carried out, its characteristics were also obtained from a test bench, the standard impeller wheel model was verified. The open-type impeller wheel was developed according to the current dimensions of standard impeller wheel and then analyzed with the numerical computations by the software ANSYS CFX (Academic license) computational fluid dynamics. The developed open-type impeller wheel works very effectively in spite of performance degradation by 5% in comparison to the closed-type impeller wheel. When working as a part of engine, the pump efficiency is 0.552-0.579. The maximum value of the pump efficiency is 0.579, it can be achieved at the highest speed of the pump (4,548 rpm and 655 l/min).
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Kang, Wen Long, Xin Yue Gu i Mu Jia Ma. "Simulated Research for Effect of Mixer Shaft Speed on Flow Field in Mixing Machine". Advanced Materials Research 619 (grudzień 2012): 451–54. http://dx.doi.org/10.4028/www.scientific.net/amr.619.451.
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Along with the rapid development of China's economy, the CFD technology has become an indispensable new technology in industrial production, and it plays an important role in the development of industry. Using computational fluid dynamics software called FLUENT. The investigation was carried out in a mixer, which its internal flow of the 3-d numerical simulation. The unstructured tetrahedron grid and unsteady multiphase turbulent calculation model were used to analyze the mixer internal fluid concentration, speed and turbulent kinetic parameters e.g., which produce changes and distributions with the different stirring shaft speed, and reveal the law of internal flow. Through the simulation result, can conclude that the numerical simulation method can truly reflect the interior complicated flow state of mixing machine, and can provide theory basis for the design and improvement of the mixing equipment.
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Semwogerere, Twaibu, R. Awichi, J. D. Lwanyaga, Esemu Joseph Noah, Verdiana G. Masanja i H. Nampala. "An Application of Computational Fluid Dynamics to Optimize Municipal Sewage Networks; A Case of Tororo Municipality, Eastern Uganda." JOURNAL OF ADVANCES IN MATHEMATICS 18 (10.01.2020): 18–27. http://dx.doi.org/10.24297/jam.v18i.8345.
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Two-phase pipe flow is a common occurrence in many industrial applications such as sewage, water, oil, and gas transportation. Accurate prediction of liquid velocity, holdup and pressure drop is of vast importance to ensure effective design and operation of fluid transport systems. This paper aimed at the simulation of a two-phase flow of air and sewage (water) using an open source software OpenFOAM. Numerical Simulations have been performed using varying dimensions of pipes as well as their inclinations. Specifically, a Standard k- turbulence model and the Volume of Fluid (VOF) free water surface model is used to solve the turbulent mixture flow of air and sewage (water). A two dimensional, 0.5m diameter pipe of 20m length is used for the CFD approach based on the Navier-Stokes equations. Results showed that the flow pattern behaviour is influenced by the pipe diameters as well as their inclination. It is concluded that the most effective way to optimize a sewer network system for Tororo Municipality conditions and other similar situations, is by adjusting sewer diameters and slope gradients and expanding the number of sewer network connections of household and industries from 535 (i.e., 31.2% of total) to at least 1,200 (70% of total).
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Yurko, Ivan, i German Bondarenko. "A New Approach to Designing the S-Shaped Annular Duct for Industrial Centrifugal Compressor". International Journal of Rotating Machinery 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/925368.
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The authors propose an analytical method for designing the inlet annular duct for an industrial centrifugal compressor using high-order Bezier curves. Using the design of experiments (DOE) theory, the three-level full factorial design was developed for determination of influence of the dimensionless geometric parameters on the output criteria. Numerical research was carried out for determination of pressure loss coefficients and velocity swirl angles using the software system ANSYS CFX. Optimal values of the slope for a wide range of geometric parameters, allowing minimizing losses in the duct, have been found. The study has used modern computational fluid dynamics techniques to develop a generalized technique for future development of efficient variable inlet guide vane systems. Recommendations for design of the s-shaped annular duct for industrial centrifugal compressor have been given.
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Woolley, S. M., C. A. Buckley, J. Pocock i G. L. Foutch. "Rheological modelling of fresh human faeces". Journal of Water, Sanitation and Hygiene for Development 4, nr 3 (9.05.2014): 484–89. http://dx.doi.org/10.2166/washdev.2014.088.
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An analysis of viscosity data from sets of raw data on the shear rheological properties of fresh human faeces was performed to generate model constants that can be used for the design of faecal treatment processes. The models selected are standard choices in computational fluid dynamics software for shear-thinning fluids. Initial screening for model selection was based on a literature review of similarly viscous materials. Results showed reasonable agreement with Power Law (PL). PL model parameters were proposed for fresh human faeces and correlated against sample properties. A PL model for shear stress as a function of moisture content was proposed.
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Chen, Long, i Binxin Wu. "Research Progress in Computational Fluid Dynamics Simulations of Membrane Distillation Processes: A Review". Membranes 11, nr 7 (7.07.2021): 513. http://dx.doi.org/10.3390/membranes11070513.
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Membrane distillation (MD) can be used in drinking water treatment, such as seawater desalination, ultra-pure water production, chemical substances concentration, removal or recovery of volatile solutes in an aqueous solution, concentration of fruit juice or liquid food, and wastewater treatment. However, there is still much work to do to determine appropriate industrial implementation. MD processes refer to thermally driven transport of vapor through non-wetted porous hydrophobic membranes, which use the vapor pressure difference between the two sides of the membrane pores as the driving force. Recently, computational fluid dynamics (CFD) simulation has been widely used in MD process analysis, such as MD mechanism and characteristics analysis, membrane module development, preparing novel membranes, etc. A series of related research results have been achieved, including the solutions of temperature/concentration polarization and permeate flux enhancement. In this article, the research of CFD applications in MD progress is reviewed, including the applications of CFD in the mechanism and characteristics analysis of different MD structures, in the design and optimization of membrane modules, and in the preparation and characteristics analysis of novel membranes. The physical phenomena and geometric structures have been greatly simplified in most CFD simulations of MD processes, so there still is much work to do in this field in the future. A great deal of attention has been paid to the hydrodynamics and heat transfer in the channels of MD modules, as well as the optimization of these modules. However, the study of momentum transfer, heat, and mass transfer mechanisms in membrane pores is rarely involved. These projects should be combined with mass transfer, heat transfer and momentum transfer for more comprehensive and in-depth research. In most CFD simulations of MD processes, some physical phenomena, such as surface diffusion, which occur on the membrane surface and have an important guiding significance for the preparation of novel membranes to be further studied, are also ignored. As a result, although CFD simulation has been widely used in MD process modeling already, there are still some problems remaining, which should be studied in the future. It can be predicted that more complex mechanisms, such as permeable wall conditions, fouling dynamics, and multiple ionic component diffusion, will be included in the CFD modeling of MD processes. Furthermore, users’ developed routines for MD processes will also be incorporated into the existing commercial or open source CFD software packages.
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Zhang, Fangyuan, i Yuji Ryu. "Simulation Study on Indoor Air Distribution and Indoor Humidity Distribution of Three Ventilation Patterns Using Computational Fluid Dynamics". Sustainability 13, nr 7 (24.03.2021): 3630. http://dx.doi.org/10.3390/su13073630.
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Due to recent industrial developments and the COVID-19 pandemic, people are spending more time indoors. Consequently, many researchers have focused on the indoor environment, and indoor air quality is considered more important for human health. Improving indoor air quality depends on effective ventilation and reasonable air distribution. In an air-conditioned room, the form of airflow organization affects air quality, so air distribution is an important aspect of air-conditioning system design. In this study, we used Airpak software by Fluent to perform numerical calculations on the indoor humidity calculation model and study the effects of different ventilation methods on indoor temperature and humidity distribution. The Reynolds averaged Navier–Stokes equation and the RNG (Re-Normalisation Group) k-epsilon model were used to predict the airflow pattern in a room, the effects of ventilation on the dew rate, the effects of different ventilation methods, and the effect of indoor wall condensation. The results of the simulation showed that the ventilation mode significantly affected the distribution of condensation on the indoor wall surface.
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Sato, T., J. M. Oh i A. Engeda. "Experimental and Numerical Investigation of the Flow in a Vaneless Diffuser of a Centrifugal Compressor Stage. Part 2: Numerical Investigation". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 219, nr 10 (1.10.2005): 1061–68. http://dx.doi.org/10.1243/095440605x31913.
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As user demands grew for improved performance and more reliable equipment and as compressor vendors sought improved analytical and design methodologies, the application of computational fluid dynamics (CFD) in the industrial world became a necessity. Fortunately, large increases in available, economic computing power together with development of improved computational methods now provide the industrial designer with much improved analytic capability. As CFD algorithms and software have continued to be developed and refined, it remains essential that validation studies be conducted in order to ensure that the results are both sufficiently accurate and can be obtained in a robust and predictable manner. Part I of this paper presented detailed flow measurements in a vaneless diffuser of a centrifugal compressor stage with a very high flow coefficient radial impeller, where measurements were carried out in the vaneless diffuser at seven radial positions downstream of the radial impeller designed for a very high flow coefficient of ϕ = 0.2. This paper, Part II, attempts to verify and validate the results numerically.
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Zhang, Yuxiang, Reamonn MacReamoinn, Philip Cardiff i Jennifer Keenahan. "Analyzing Wind Effects on Long-Span Bridges: A Viable Numerical Modelling Methodology Using OpenFOAM for Industrial Applications". Infrastructures 8, nr 9 (26.08.2023): 130. http://dx.doi.org/10.3390/infrastructures8090130.
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Aerodynamic performance is of critical importance to the design of long-span bridges. Computational fluid dynamics (CFD) modelling offers bridge designers an opportunity to investigate aerodynamic performance for long-span bridges during the design phase as well as during operation of the bridge. It offers distinct advantages when compared with the current standard practice of wind tunnel testing, which can have several limitations. The proposed revisions to the Eurocodes offer CFD as a methodology for wind analysis of bridges. Practicing engineers have long sought a computationally affordable, viable, and robust framework for industrial applications of using CFD to examine wind effects on long-span bridges. To address this gap in the literature and guidance, this paper explicitly presents a framework and demonstrates a workflow of analyzing wind effects on long-span bridges using open-source software, namely FreeCAD, OpenFOAM, and ParaView. Example cases are presented, and detailed configurations and general guidance are discussed during each step. A summary is provided of the validation of this methodology with field data collected from the structural health monitoring (SHM) systems of two long-span bridges.
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Florio, Laurie A. "Direct simulation of thermally and mechanically coupled particle-laden flow". SIMULATION 98, nr 5 (30.10.2021): 363–87. http://dx.doi.org/10.1177/00375497211055104.
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This work describes a unique technique to simulate continuously and directly coupled fluid flow and moving particles including both mechanical and thermal interactions between the flow, particles, and flow paths. The particles/flow paths are discretized within a computational fluid dynamics flow domain so that the local flow and temperature field conditions surrounding each particle or other solid body are known along with the local temperature distribution within the particle and other solids. Contact conduction between solid bodies including contact resistance, conjugate heat transfer at the fluid–solid interfaces, and even radiation exchanges between solid surfaces and between solid surfaces and the fluid are incorporated in the thermal interactions and a soft collision model simulates the solid body mechanical contact. The ability to capture these local flow and thermal effects removes reliance on correlations for fluid forces and for heat transfer coefficients/exchange and removes restrictions on the flow regime and particle size and volume fraction considered. Larger particle sizes and higher particle concentration conditions can be studied with local effects captured. The method was tested for a range of particle thermal and mechanical properties, driving pressures, and for limited radiation parameters. The results reveal important information about the basic thermal and flow phenomena that cannot be obtained in standard modeling methods and demonstrate the utility of the modeling method. The technique can be applied to examine phenomena dependent on local thermal conditions such as chemical reactions, material property variation, agglomerate formation, and phase change. The methods can also be used as a basis for machine learning algorithm development for flows with large particle counts so that more detailed phenomena can be considered compared to those provided by standard techniques with reduced computational costs compared to those with fully resolved particles in the flow.
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Mohamad, Barhm, Károly Jalics i Andrei Zelentsov. "Investigation and optimization of the acoustic performance of formula student race car intake system using coupled modelling techniques". Design of Machines and Structures 9, nr 1 (2019): 13–23. http://dx.doi.org/10.32972/dms.2019.002.
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The University of Miskolc has previously designed and prototyped several race cars for the Formula Student (FS) competition. Unfortunately, none of these cars utilized air intake systems meeting all the requirements of regulations. Intake system are used to feed the engine with sufficient amount of air for complete combustion inside the combustion chamber to produce maximum power. The air flow during flowing produce sound waves due to rate of turbulence and boundary layer separation, and according to standard regulation this sound should be controlled minimum as possible. Recent advances in modelling procedures for accurate performance prediction have led to the development of modelling methods for practical intake system components in commercial design. Engine designers need simple and fast modelling tools, especially in the preliminary design evaluation stages. In this study, commercial software Solidworks and advanced design software Creo 4.0 were used in addition for that Computational Fluid Dynamics (CFD) analysis is performed. Frequency domain analysis is made to receive behaviour of the entire system under assumed conditions.
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López-Montoya, Tatiana, Carlos Andrés Bustamante, Cesar Nieto-Londoño i Natalia Gómez-Velásquez. "Computational study of particle distribution development in a cold-flow laboratory scale downer reactor". CT&F - Ciencia, Tecnología y Futuro 11, nr 1 (30.06.2021): 33–46. http://dx.doi.org/10.29047/01225383.172.
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The use of downer reactors (gas-solid co-current downward flow) in the Fluid Catalytic cracking (FCC) process for the upgrading of heavy crude oil into more valuable products has gradually become more common in the last decades. This kind of reactor is characterized by having homogeneous axial and radial flow structures, no back mixing, and shorter residence times as compared with the riser reactor type. Although downer reactors were introduced a long time ago, available information in literature about the multiphase hydrodynamic behavior at FCC industrial scale is scarce. Therefore, it is necessary to conduct experimental and computational studies to enhance the understanding of the hydrodynamics of two-phase co-current downward flow. The Computational Fluids Dynamics (CFD) software, Ansys Fluent, is used to study two-dimensional gas (air) and solid (catalyst particle) flow in a downer section of a cold-flow circulation fluidized bed (CFB) system at a laboratory scale. The implemented computational model is validated by comparing numerical results for solid velocity and volume fraction with measurements carried out on a CFB system using a fiber-optic probe laser velocimeter. According to numerical results obtained for different gas velocity and solid flux, flow development cannot only be estimated by considering solid axial velocity changes along the reactor; it is also necessary to take into account solid volume fraction axial variations as radial profiles can change even when velocity profiles are developed.
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Abd. Karim, Izian, Chun Hean Lee, Antonio J. Gil i Javier Bonet. "A two-step Taylor-Galerkin formulation for fast dynamics". Engineering Computations 31, nr 3 (28.04.2014): 366–87. http://dx.doi.org/10.1108/ec-12-2012-0319.
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Purpose – The purpose of this paper is to present a new stabilised low-order finite element methodology for large strain fast dynamics. Design/methodology/approach – The numerical technique describing the motion is formulated upon the mixed set of first-order hyperbolic conservation laws already presented by Lee et al. (2013) where the main variables are the linear momentum, the deformation gradient tensor and the total energy. The mixed formulation is discretised using the standard explicit two-step Taylor-Galerkin (2TG) approach, which has been successfully employed in computational fluid dynamics (CFD). Unfortunately, the results display non-physical spurious (or hourglassing) modes, leading to the breakdown of the numerical scheme. For this reason, the 2TG methodology is further improved by means of two ingredients, namely a curl-free projection of the deformation gradient tensor and the inclusion of an additional stiffness stabilisation term. Findings – A series of numerical examples are carried out drawing key comparisons between the proposed formulation and some other recently published numerical techniques. Originality/value – Both velocities (or displacements) and stresses display the same rate of convergence, which proves ideal in the case of industrial applications where low-order discretisations tend to be preferred. The enhancements introduced in this paper enable the use of linear triangular (or bilinear quadrilateral) elements in two dimensional nearly incompressible dynamics applications without locking difficulties. In addition, an artificial viscosity term has been added into the formulation to eliminate the appearance of spurious oscillations in the vicinity of sharp spatial gradients induced by shocks.
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Tsai, Shih-Pang, Wei Wu, Hiroyoshi Sota, Toshiki Hirogaki i Eiichi Aoyama. "Investigation of Air Filter Properties of Flash-Spinning Nanofiber Non-Woven Fabric". International Journal of Automation Technology 16, nr 5 (5.09.2022): 654–65. http://dx.doi.org/10.20965/ijat.2022.p0654.
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Using computational fluid dynamics (CFD) technology, a stable manufacturing method for polymeric nanofiber non-woven fabrics based on an improved melt-blowing method and flash spinning is realized to achieve mass productivity. Subsequently, a method to predict filter efficiency using two production methods based on the effects of thickness, filling rate, and fiber diameter on filtration performance is developed to establish a filter design via CFD technology. CFD models featuring uniform fiber diameters are proposed. Next, the pressure loss and flow resistivity are calculated using CFD flow analysis software, as in a filter experiment. The proposed fiber diameter distribution model yields results similar to the experimental value, and the relationship among filling rate, fiber diameter, and flow resistivity is verified. The non-woven filter fabricated in this study demonstrates superior filtration properties, based on the results. Additionally, a method to satisfy both low pressure loss (low flow resistivity) and high filtration efficiency is discussed. Although the pressure loss increases, the filter yields a value below the standard for high-performance face masks, since the fiber diameter is on the nano-order.
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Lee, Junsik, i Jae-Hak Lee. "Study on Turbulence Intensity Behavior under a Large Range of Temperature Variation". Processes 8, nr 11 (3.11.2020): 1403. http://dx.doi.org/10.3390/pr8111403.
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The turbulence intensity (TI) is defined as the ratio of fluctuation from the standard deviation of wind velocity to the mean value. Many studies have been performedon TI for flow dynamics and adapted various field such as aerodynamics, jets, wind turbines, wind tunnel apparatuses, heat transfer, safety estimation of construction, etc.The TI represents an important parameter for determining the intensity of velocity variation and flow quality in industrial fluid mechanics. In this paper, computational fluid dynamic (CFD) simulation of TI alteration with increasing temperature has been performed using the finite volume method. A high-temperature—maximum 300 degrees Celsius (°C)—wind tunnel test rig has been used as theapparatus, and velocity was measured by an I-type hot-wire anemometer. The velocity and TI of the core test section were operated at several degrees of inlet temperatures at anair velocity of 20 m/s. The magnitude of TI has a relationship with boundary layer development. The TI increased as temperature increased due to turbulence created by the non-uniformities.
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Taylor, Adam C., Stephen Beirne, Gursel Alici i Gordon G. Wallace. "System and process development for coaxial extrusion in fused deposition modelling". Rapid Prototyping Journal 23, nr 3 (18.04.2017): 543–50. http://dx.doi.org/10.1108/rpj-10-2015-0141.
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Purpose This paper aims to design and test a system capable of coaxial fused deposition modelling (FDM) and assess the coaxial fibres produced for their coaxial concentricity. The goal is to achieve concentricity values below the literature standard of 15 per cent. Design/methodology/approach This research discusses the design of the coaxial nozzle internal geometry and validates the modelling process by using computational fluid dynamics to assess its flow profile. Sequentially, this paper discusses the abilities of current additive manufacturing (AM) technology in the production of the coaxial nozzle. Findings The methodology followed has produced coaxial fibres with concentricity values as low as 2.89 per cent and also identifies a clear speed suitable for coaxial printing using polylactic acid (PLA) as the internal and external materials. Research limitations/implications The concentricity of the printed fibres is heavily influenced by the feed rate for the thermoplastic feedstock. This in turn alters the viscosity of the material to be printed, implying that a relationship exists between feed rate and print temperature, which can be further optimised to potentially obtain higher concentricity values. Practical implications This paper adds reliability and repeatability to the production of coaxially printed structures, the likes of which has numerous potential applications for biological printing. Originality/value The outcomes of this study will provide an AM platform to alter the paradigm of biofabrication by introducing a new level of versatility to the construction of biofabricated structures.
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Zhao, Benzhong, Christopher W. MacMinn, Bauyrzhan K. Primkulov, Yu Chen, Albert J. Valocchi, Jianlin Zhao, Qinjun Kang i in. "Comprehensive comparison of pore-scale models for multiphase flow in porous media". Proceedings of the National Academy of Sciences 116, nr 28 (21.06.2019): 13799–806. http://dx.doi.org/10.1073/pnas.1901619116.
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Multiphase flows in porous media are important in many natural and industrial processes. Pore-scale models for multiphase flows have seen rapid development in recent years and are becoming increasingly useful as predictive tools in both academic and industrial applications. However, quantitative comparisons between different pore-scale models, and between these models and experimental data, are lacking. Here, we perform an objective comparison of a variety of state-of-the-art pore-scale models, including lattice Boltzmann, stochastic rotation dynamics, volume-of-fluid, level-set, phase-field, and pore-network models. As the basis for this comparison, we use a dataset from recent microfluidic experiments with precisely controlled pore geometry and wettability conditions, which offers an unprecedented benchmarking opportunity. We compare the results of the 14 participating teams both qualitatively and quantitatively using several standard metrics, such as fractal dimension, finger width, and displacement efficiency. We find that no single method excels across all conditions and that thin films and corner flow present substantial modeling and computational challenges.
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Li, Minghao, Huaixian Yin, Zhen Zhang i Hongxin Zhang. "Optimization Determination Method for the Explicit Equation of Scraper Motion Quantity in an Elliptical Rotor Scraper Pump". Machines 11, nr 9 (29.08.2023): 867. http://dx.doi.org/10.3390/machines11090867.
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Addressing the inherent drawbacks of conventional positive displacement pumps, such as complex structure, poor sealing, low volumetric efficiency, and high noise, an innovative design of an elliptical rotor scraper pump (ERSP) was proposed. By segregating the pump chamber into high-pressure and low-pressure cavities, the scraper minimizes operational noise and significantly improves volumetric efficiency. To analyze the motion state of the ERSP, a mathematical model was established, determining the coordinated movement between the scraper and rotor using different optimization methods. The equations of coordinated action were derived and validated with relevant software through constraints applied to three algorithms and polynomial fitting. The flow field model of the ERSP was defined based on the established coordinated movement equation, and computational fluid dynamics (CFD) simulations were conducted to analyze pressure and velocity fields within the pump. A prototype of the ERSP was fabricated and tested, confirming its feasibility and advantages in enhancing fluid pressure and flow speed. This study provides valuable insights into the dynamic characteristics and structural optimization of fluid rotor pumps, contributing to anticipating and resolving potential faults and promoting the development of fluid power machinery.
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Elhadary, Mohamed I., Abdullah Mossa Y. Alzahrani, Reda M. H. Aly i Bahaa Elboshy. "A Comparative Study for Forced Ventilation Systems in Industrial Buildings to Improve the Workers’ Thermal Comfort". Sustainability 13, nr 18 (14.09.2021): 10267. http://dx.doi.org/10.3390/su131810267.
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The appropriate ventilation for factory spaces with regard to volume flow rate and air velocity inside the factory is one of the most important factors in the improvement of the thermal comfort of workers and in the reduction of the percentage of pollution they are exposed to, which in turn helps to improve the work environment and increase productivity. It also could improve the performance of machines. Hence, overheating can cause various problems and malfunctions. In this study, three types of mechanical ventilation systems are compared: the wall fan extract ventilation system, the roof fan extract ventilation system, and the spot cooling system. The Ansys software has been used to conduct the computational fluid dynamics (CFD) simulations for the different cases and the ventilation effectiveness factor (VEF) has been used to compare the performances of the three systems. The ventilation factor notably relies on the temperature distribution produced through the modeling and the results show that the most optimal system that can be used for similar factory spaces is the forced ventilation system. Finally, it is also the best in terms of energy consumption, despite the increase in the initial cost of its installation.
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Venczel, Márk, Gabriella Bognár i Árpád Veress. "Temperature-Dependent Viscosity Model for Silicone Oil and Its Application in Viscous Dampers". Processes 9, nr 2 (11.02.2021): 331. http://dx.doi.org/10.3390/pr9020331.
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Silicone fluids belong to the group of pseudoplastic non-Newtonian fluids with complex rheological characteristics. They are considered in basic and applied researches and in a wide range of industrial applications due to their favorable physical and thermal properties. One of their specific field of applications in the automotive industry is the working fluid of viscous torsional vibration dampers. For numerical studies in the design and development phase of this damping product, it is essential to have thorough rheological knowledge and mathematical description about the silicone oil viscosity. In the present work, adopted rheological measurement results conducted on polydimethylsiloxane manufactured by Wacker Chemie with initial viscosity of 1000 Pas (AK 1 000 000 STAB silicone oil) are processed. As a result of the parameter identification by nonlinear regression, the temperature-dependent parameter curves of the Carreau–Yasuda non-Newtonian viscosity model are generated. By implementing these parameter sets into a Computational Fluid Dynamics (CFD) software, a temperature- and shear-rate-dependent viscosity model of silicone fluid was tested, using transient flow and thermal simulations on elementary tube geometries in the size range of a real viscous torsional vibration damper’s flow channels and filling chambers. The numerical results of the finite volume method provide information about the developed flow processes, with especial care for the resulted flow pattern, shear rate, viscosity and timing.
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Daud, H. A., Q. Li, O. A. Bég i S. A. A. AbdulGhani. "Numerical investigations of wall-bounded turbulence". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, nr 5 (28.04.2011): 1163–74. http://dx.doi.org/10.1177/09544062jmes2524.
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This article investigates numerically the effects on turbulence in two important flow regimes – fully developed channel flow and flow past a NACA 0012 airfoil, using the commercial software – FLUENT 6.3. The solution accuracy is explored via a sensitivity study of mesh type and quality effects, employing different element types (e.g. quadrilateral and triangular). The significance of this article is to elucidate the effects of enhancement wall treatment and standard wall function on the turbulent boundary layer. Furthermore, three different turbulence models have been utilized in this study ( k−ε, re-normalization group (RNG), and shear stress transport (SST) k−ω). The numerical solutions have been compared with available direct numerical simulation (DNS) and experimental data and very good correlation has been achieved. In addition, the statistical turbulence results related to the RNG turbulence model are shown to yield much closer correlation with DNS and experimental data. The effect of Reynolds number ( Reτ = 590 and Reτ = 2320) is studied for the channel flow regime. The near wall resolution is examined in detail by controlling in the y+ value. A particularly important objective in this study is to highlight the importance of validation in computational fluid dynamics (CFD) turbulence simulations and sustaining a high degree of accuracy, aspects which are often grossly neglected with industrial CFD software. The authors therefore hope to provide some guidance to applied aerodynamicists utilizing CFD in future studies.
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Amirante, Riccardo, i Paolo Tamburrano. "Tangential inlet cyclone separators with low solid loading". Engineering Computations 33, nr 7 (3.10.2016): 2090–116. http://dx.doi.org/10.1108/ec-07-2015-0191.
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Purpose The purpose of this paper is to propose an effective methodology for the industrial design of tangential inlet cyclone separators that is based on the fully three-dimensional (3D) simulation of the flow field within the cyclone coupled with an effective genetic algorithm. Design/methodology/approach The proposed fully 3D computational fluid dynamics (CFD) model makes use of the Reynold stress model for the accurate prediction of turbulence, while the particle trajectories are simulated using the one-way coupling discrete phase, which is a model particularly effective in case of low concentration of dust. To validate the CFD model, the numerical predictions are compared with experimental data available in the scientific literature. Eight design parameters were chosen, with the two objectives being the minimization of the pressure drop and the maximization of the collection efficiency. Findings The optimization procedure allows the determination of the Pareto Front, which represents the set of the best geometries and can be instrumental in taking an optimal decision in the presence of such a trade-off between the two conflicting objectives. The comparison among the individuals belonging to the Pareto Front with a more standard cyclone geometry shows that such a CFD global search is very effective. Practical implications The proposed procedure is tested for specific values of the operating conditions; however, it has general validity and can be used in place of typical procedures based on empirical models or engineers’ experience for the industrial design of tangential inlet cyclone separators with low solid loading. Originality/value Such an optimization process has never been proposed before for the design of cyclone separators; it has been developed with the aim of being both highly accurate and compatible with the industrial design time.
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Cao, M., K. W. Wang, L. DeVries, Y. Fujii ,, W. E. Tobler ,, G. M. Pietron ,, T. Tibbles , i J. McCallum. "Steady State Hydraulic Valve Fluid Field Estimator Based on Non-Dimensional Artificial Neural Network (NDANN)". Journal of Computing and Information Science in Engineering 4, nr 3 (1.09.2004): 257–70. http://dx.doi.org/10.1115/1.1765119.
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An automatic transmission (AT) hydraulic control system includes many spool-type valves that have highly asymmetric flow geometry. A simplified flow field model based on a lumped geometry is computationally efficient. However, it often fails to account for asymmetric flow characteristics, leading to an inaccurate analysis. An accurate analysis of their flow fields typically requires using the computational fluid dynamics (CFD) technique, which is numerically inefficient and time consuming. In this paper, a new hydraulic valve fluid field model is developed based on non-dimensional artificial neural networks (NDANNs) to provide an accurate and numerically efficient tool in AT control system design applications. A grow-and-trim procedure is proposed to identify critical non-dimensional inputs and optimize the network architecture. A hydraulic valve testing bench is designed and built to provide data for neural network model development. NDANN-based fluid force and flow rate estimators are established based on the experimental data. The NDANN models provide more accurate predictions of flow force and flow rates under broad operating conditions (such as different pressure drops and valve openings) compared with conventional lumped flow field models. Because of its non-dimensional characteristic, the NDANN fluid field estimator also exhibits good input-output scalability, which allows the NDANN model to estimate the fluid force and flow rate even when the operating condition parameter or design geometry parameters are outside the range of the training data. That is, although the operating/geometry parameter values are outside the range of the training sets, the non-dimensional values of the specific operating/geometry parameters are still within the training range. This feature makes the new model a potential candidate as a system design tool.
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Lauritzen, P. H., P. A. Ullrich, C. Jablonowski, P. A. Bosler, D. Calhoun, A. J. Conley, T. Enomoto i in. "A standard test case suite for two-dimensional linear transport on the sphere: results from a collection of state-of-the-art schemes". Geoscientific Model Development 7, nr 1 (14.01.2014): 105–45. http://dx.doi.org/10.5194/gmd-7-105-2014.
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Abstract. Recently, a standard test case suite for 2-D linear transport on the sphere was proposed to assess important aspects of accuracy in geophysical fluid dynamics with a "minimal" set of idealized model configurations/runs/diagnostics. Here we present results from 19 state-of-the-art transport scheme formulations based on finite-difference/finite-volume methods as well as emerging (in the context of atmospheric/oceanographic sciences) Galerkin methods. Discretization grids range from traditional regular latitude–longitude grids to more isotropic domain discretizations such as icosahedral and cubed-sphere tessellations of the sphere. The schemes are evaluated using a wide range of diagnostics in idealized flow environments. Accuracy is assessed in single- and two-tracer configurations using conventional error norms as well as novel diagnostics designed for climate and climate–chemistry applications. In addition, algorithmic considerations that may be important for computational efficiency are reported on. The latter is inevitably computing platform dependent. The ensemble of results from a wide variety of schemes presented here helps shed light on the ability of the test case suite diagnostics and flow settings to discriminate between algorithms and provide insights into accuracy in the context of global atmospheric/ocean modeling. A library of benchmark results is provided to facilitate scheme intercomparison and model development. Simple software and data sets are made available to facilitate the process of model evaluation and scheme intercomparison.
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Lauritzen, P. H., P. A. Ullrich, C. Jablonowski, P. A. Bosler, D. Calhoun, A. J. Conley, T. Enomoto i in. "A standard test case suite for two-dimensional linear transport on the sphere: results from a collection of state-of-the-art schemes". Geoscientific Model Development Discussions 6, nr 3 (23.09.2013): 4983–5076. http://dx.doi.org/10.5194/gmdd-6-4983-2013.
Pełny tekst źródłaStreszczenie:
Abstract. Recently, a standard test case suite for 2-D linear transport on the sphere was proposed to assess important aspects of accuracy in geophysical fluid dynamics with a "minimal" set of idealized model configurations/runs/diagnostics. Here we present results from 19 state-of-the-art transport scheme formulations based on finite-difference/finite-volume methods as well as emerging (in the context of atmospheric/oceanographic sciences) Galerkin methods. Discretization grids range from traditional regular latitude-longitude grids to more isotropic domain discretizations such as icosahedral and cubed-sphere tessellations of the sphere. The schemes are evaluated using a wide range of diagnostics in idealized flow environments. Accuracy is assessed in single- and two-tracer configurations using conventional error norms as well as novel diagnostics designed for climate and climate-chemistry applications. In addition, algorithmic considerations that may be important for computational efficiency are reported on. The latter is inevitably computing platform dependent, The ensemble of results from a wide variety of schemes presented here helps shed light on the ability of the test case suite diagnostics and flow settings to discriminate between algorithms and provide insights into accuracy in the context of global atmospheric/ocean modeling. A library of benchmark results is provided to facilitate scheme intercomparison and model development. Simple software and data-sets are made available to facilitate the process of model evaluation and scheme intercomparison.
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Araiz, Miguel, Álvaro Casi, Leyre Catalán, Patricia Aranguren i David Astrain. "Thermoelectric Generator with Passive Biphasic Thermosyphon Heat Exchanger for Waste Heat Recovery: Design and Experimentation". Energies 14, nr 18 (14.09.2021): 5815. http://dx.doi.org/10.3390/en14185815.
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One of the measures to fight against the current energy situation and reduce the energy consumption at an industrial process is to recover waste heat and transform it into electric power. Thermoelectric generators can be used for that purpose but there is a lack of experimental studies that can bring this technology closer to reality. This work presents the design, optimizations and development of two devices that are experimented and compared under the same working conditions. The hot side heat exchanger of both generators has been designed using a computational fluid dynamics software and for the cold side of the generators two technologies have been analysed: a finned dissipater that uses a fan and free convection biphasic thermosyphon. The results obtained show a maximum net generation of 6.9W in the thermoelectric generator with the finned dissipater; and 10.6W of power output in the generator with the biphasic thermosyphon. These results remark the importance of a proper design of the heat exchangers, trying to get low thermal resistances at both sides of the thermoelectric modules, as well as, the necessity of considering the auxiliary consumption of the equipment employed.
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Yu, Jinghua, Congcong Qian, Jingang Zhao, Junwei Tao, Kangxin Leng i Xinhua Xu. "Indoor Air Quality Improvement in Public Toilets at Railway Stations in China: A Field and Numerical Study". Sustainability 15, nr 11 (29.05.2023): 8720. http://dx.doi.org/10.3390/su15118720.
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This study investigated the air quality and ventilation systems of 22 public toilets in 10 railway stations in China. Approximately 80% of public toilets meet the standard for ammonia concentration in Class I toilets, while 20% exceed the standard. It was found that the concentration of pollutants is mainly related to the number of toilet users and the ventilation system. In 20% of public toilets, the change in ammonia concentration was delayed by about 1 to 2 h with the change in hourly service number. In order to improve the air quality, a design method for calculating the number of toilet cubicles was proposed. Results show that the service capacity of the cubicle per hour (SCCH) of a female toilet is 12, the SCCH of male toilets is related to the ratio of squatting pans to urinals (RSU), which is suggested to be 1:1~1:0.8, and the corresponding SCCH is 16~20. Then, the effect of different ventilation forms was simulated by computational fluid dynamics (CFD) 2019 software. The results show that the bottom exhaust was better than the top exhaust and that the fresh air supply system is unnecessary. The recommended ventilation rate for toilets is 20 air changes per hour (ACH). The scale design method of toilets proposed in this paper was meant to address the gender imbalance and avoid queuing and provides a reference for the renovation and design of public toilets.
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Pasymi, Pasymi, Y. W. Budhi, A. Irawan i Y. Bindar. "Three dimensional cyclonic turbulent flow structures at various geometries, inlet-outlet orientations and operating conditions". Journal of Mechanical Engineering and Sciences 12, nr 4 (27.12.2018): 4300–4328. http://dx.doi.org/10.15282/jmes.12.4.2018.23.0369.
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Flow structure inside a chamber greatly determines the process performances. Therefore, the flow structure inside a chamber are often constructed in such a way as an effort to obtain equipment performances in accordance with the expectations. This study explored flow structure inside several chamber geometries and operating conditions. Three types of chamber, namely; GTC, DTC and TJC were set as the investigated chambers. The Computational Fluid Dynamics technique, supported by some experimental data from the literature, is used as an investigation method. The RANS based models, under Ansys-Fluent software were used in this numerical investigation. Simulation results revealed that the flow structures of GTC and DTC are predominantly created by spiral and vortex patterns. The vortex stabilizer diameter in the GTC affects the vortex pattern, velocity profile and pressure drop. The flow structure of DTC presents the most complex behavior. The flow structure inside TJC, in the case of unconfined outlet boundary, is characterized by the helical and wavy jet pattern. This structure is determined by the initial tangential intensity (IIT) and the inlet aspect ratio (RIA). The structures of vortex, helical, and wavy axial flow are properly constructed and visualized in this paper. There is no a turbulence model which is always superior to the other models, consistently. The standard k-ε model exhibits the realistic and robust performances among all of investigatied cases.
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Akanova, Guldana, Laila Sagatova, Lazizjon Atakulov, Umid Kayumov i Muhammad Istamov. "Choosing the flow part geometric shape of the dredge pumps for viscous fluids". Mining of Mineral Deposits 15, nr 4 (grudzień 2021): 75–83. http://dx.doi.org/10.33271/mining15.04.075.
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Purpose. Search for the possibility of increasing the efficiency of dredge pumps for viscous fluids by determining the rational values of the blade-outlet inclination angles in the pump impellers. Methods. During the research, the following is used: theoretical studies of the structure of the viscous fluids flowing through the flow part of dredge pumps; the method of three-dimensional software-simulation modeling of hydrodynamic processes using the Ansys software package; the methods of rational experiment planning for selecting the values of the number of points in the computational grid when optimizing the geometric parameters of the dredge pump impellers; methods of mathematical statistics and correlation analysis. Findings. It has been proven that the main reason for the failure of the flow part components in the dredge pumps is the manifestation of the influence of cavitation processes, which can be eliminated by changing the blade-outlet inclination angles in the pump impellers. A software-simulation complex for the automated design of the flow parts in the dredge pumps has been developed based on the use of optimization algorithms and computational fluid dynamics methods, which makes it possible to design dredge pumps with optimal characteristics that ensure their efficient operation with maximum efficiency values. It has been determined that one of the main factors influencing the head developed by dredge pumps and the efficiency value is the blade-outlet inclination angle in the pump impellers. Originality. Scientific novelty is in the scientific substantiation and development of a simulation-mathematical method for calculating the geometric parameters of the flow part in dredge pumps for viscous fluids at the design stage. Practical implications. The developed method for determining the rational blade-outlet inclination angles of the impellers in the dredge pumps for viscous fluids can be recommended to scientific-research and industrial organizations for use in the improvement, design and operation of the dredge pumps.
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Kumar Srivastava, Ashish. "An investigation on the efficiency of the CNG engine's intake manifold and injection systems". Journal of Futuristic Sciences and Applications 1, nr 2 (2018): 60–69. http://dx.doi.org/10.51976/jfsa.121807.
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Variations such as piston, exhaust, and manifold were prerequisites in the internal-combustion engine to achieving effective torque, power, and productivity. The reduction of toxic gas emissions is another benefit. Engine performance was improved due to these variables. The intake manifold's primary function is to ensure that the air-fuel mixture is distributed uniformly throughout the cylinders of the engine. The development of an intake manifold and an investigation into the effects of CNG SPFI performance variables such as injection position and air-fuel ratio. Deflection and stress have been measured in a variety of systems. The air-fuel mixture's homogeneity index was also tested by moving the injection point in an examination of computational fluid dynamics. In addition, the k turbulence approach was used to show the impact of turbulence on the aircraft. In this case, the engine's performance was anticipated using 1D experimentation software, and the results were compared to those obtained by simulation.
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Nasir, Abdulbasit, Edessa Dribssa, Misrak Girma i Tamerat Demeke. "A Comparative Study of Impeller Modification Techniques on the Performance of the Pump as a Turbine". International Journal of Rotating Machinery 2022 (14.11.2022): 1–16. http://dx.doi.org/10.1155/2022/1944753.
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The extensive use of the pump as a turbine (PAT) for micro-hydropower applications has a significant value from economic and technical viewpoints. However, the unavailability of the characteristics curve and relatively lower efficiency are the two basic limitations when considering pumps for power-generating applications. In this paper, the performance of the PAT is analyzed using the computational fluid dynamics (CFD) software called Ansys CFX in conjunction with standard k - ε . Then, experiments were done to verify the results of the simulation. Measurement inaccuracy effects are also taken into account. The initial performance of the PAT is refined by controlling basic design parameters (i.e., increasing the number of impeller blades, decreasing blade thickness, blade tip rounding, and adjusting blade inlet angle). Additionally, a new modification method known as blade grooving is also introduced in this research. Finally, all listed modification techniques are applied simultaneously to achieve maximum performance. The output of the study confirms that the adopted modification techniques have a positive effect on performance improvement. When the number of impellers is increased, the power output is enhanced by 5.72%, and blade grooving provides the most efficiency improvement, i.e., 7.00%. But decreasing blade thickness has no remarkable impact on the performance; the power output and efficiency are improved by 1.24% and 2.60%, respectively. The maximum performance improvement was achieved when the modification techniques are applied simultaneously with 10.56 and 10.20 percent of power and efficiency increments, respectively. From the entire study, it can be concluded that the chosen design parameters have an important effect on stabilizing the internal flow, decreasing the required head, decreasing the hydraulic loss in the impeller, and increasing the overall performance. The study also helps to figure out which modification technique is the most practical.
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Bishawi, Muath, Bradley Feiger, Neel Kurupassery, Konstantinos Economopoulos, Paul Suhocki, Theodore Pappas, George Truskey i Amanda Randles. "Drainage Performance of a Novel Catheter Designed to Reduce Drainage Catheter Failure". Journal of Clinical Interventional Radiology ISVIR 4, nr 01 (kwiecień 2020): 09–15. http://dx.doi.org/10.1055/s-0040-1708570.
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Abstract Objective Efficient flow of fluids through drainage/infusion catheters is affected by surrounding tissue, organ compression, and scar tissue development, limiting or completely obstructing flow through drainage holes. In this work, we introduce a novel three-dimensional (3D) drainage catheter with protected side holes to reduce flow blockages. We then compare its drainage performance to standard straight and pigtail catheters using computer-generated catheter designs and flow analysis software. Methods Drainage performance was computed as flow rate through the catheter for a given pressure differential. Each catheter contained drainage holes on the distal (insertion) end and a single outlet (hub) hole open to atmosphere. Computational fluid dynamics using ANSYS AIM 18.2 was used to simulate flow through the catheter and examine drainage performance based on variations to the following parameters: (1) side hole shape, (2) cross-sectional area of the catheters, (3) number of side holes, and (4) cross-sectional area of the side holes. Results Drainage through the newly introduced catheter in all simulations was nearly identical to standard pigtail and straight catheters. While working to optimize the 3D catheter design, we found that the changes in side hole shape and side hole cross-sectional area had little effect on the total flow rate through the catheters but had a large impact on flow rate through the side hole nearest to the hub (proximal hole). Additionally, the majority of flow in all catheters occurred at the most proximal 1 to 3 side holes closest to hub, with relatively little flow occurring at side holes more distally located (closest to insertion end). The 3D catheter demonstrated no changes in flow characteristics when the coiled segment was occluded, giving it an advantage over other catheter types when the catheter is compressed by surrounding tissue or other external obstruction. Conclusions The majority of fluid flow in catheters with a diameter of 4.67 mm (14 Fr) or smaller occurred at the most proximal 1 to 3 side holes. A novel 3D coiled catheter design can protect these proximal holes from external blockage while maintaining drainage performance compared with standard straight and pigtail catheters.
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Seyfeddine, Mona, Samuel Vorlet, Nicolas Adam i Giovanni De Cesare. "Holistic Design Approach of a Throttled Surge Tank: The Case of Refurbishment of Gondo High-Head Power Plant in Switzerland". Water 12, nr 12 (8.12.2020): 3440. http://dx.doi.org/10.3390/w12123440.
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In order to increase the installed capacity, the refurbishment of Gondo high-head power plant required a modification of the existing surge tank by installing a throttle at its entrance. In a previous study, the geometry of this throttle was optimized by physical modeling to achieve the target loss coefficients as identified by a transient 1D numerical analysis. This study complements previous analyses by means of 3D numerical modeling using the commercial software ANSYS-CFX 19 R1. Results show that: (i) a 3D computational fluid dynamics (CFD) model predicts sufficiently accurate local head loss coefficients that agree closely with the findings of the physical model; (ii) in contrast to a standard surge tank, the presence of an internal gallery in the surge tank proved to be of insignificant effect on a surge tank equipped with a throttle, as the variations in the section of the tank cause negligible local losses compared to the ones induced by the throttle; (iii) CFD investigations of transient flow regimes revealed that the head loss coefficient of the throttle only varies for flow ratios below 20% of the total flow in the system, without significantly affecting the conclusions of the 1D transient analysis with respect to minimum and maximum water level in the surge tank as well as pressure peaks below the surge tank. This study highlights the importance of examining the characteristics of a hydraulic system from a holistic approach involving hybrid modeling (1D, 3D numerical and physical) backed by calibration as well as validation with in-situ measurements. This results in a more rapid and economic design of throttled surge tanks that makes full use of the advantages associated with each modeling strategy.
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Tran, Ngoc-Tien, i Duc-Minh Nguyen. "Analysis of flow characteristics of cylindrical and helical type multi-lobe roots blower". EUREKA: Physics and Engineering, nr 1 (19.01.2023): 67–75. http://dx.doi.org/10.21303/2461-4262.2023.002578.
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Roots blower is a positive displacement machine that has the advantage of a larger flow than conventional blowers. Roots blowers are widely used in industrial production such as chemicals, food, medical, etc. However, during actual operation, this type of machine often achieves low performance. One of the issues that greatly affect performance is the flow characteristics of the blower. Flow characteristics include factors related to flow rate, pressure, and flow phenomena in the blower chamber. Flow characteristic analysis is a complex problem in hydraulic machines. Flow analysis helps to investigate the motion of the flow to design high-performance machines. This study uses a mathematical model of gear theory to design the rotor profile with cylindrical and helical lobes of the multi-lobe Roots blower. The rotor profile is formed on the principle that the ellipse rolls without slipping on the base circle. On the basis of the mathematical model of the rotor profile, the paper compares the flow rate and pressure characteristics of the two blowers. The fluid dynamics analysis model was built on ANSYS software. The structural grid model is also built to increase the computational efficiency of the mathematical model. The lobes are embedded and rotated in the blower chamber. The results show that with the same radial and axial dimensions, the cylindrical lobe has a larger flow. However, the helical lobe has a more stable flow quality than the cylindrical lobe (15.2 % less flow fluctuation). In terms of pressure, the helical lobe type has a higher pressure than the cylindrical lobe type. In addition, the helical lobe type also reduces the influence of eddy currents acting on the blower chamber walls and rotors. That results in increased blower efficiency. The results of the paper will be a reliable basis for reducing time in the development of multi-lobe Roots blowers with high performance
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Jha, Sudhanshu Kumar, Shiv Prakash, Rajkumar Singh Rathore, Mufti Mahmud, Omprakash Kaiwartya i Jaime Lloret. "Quality-of-Service-Centric Design and Analysis of Unmanned Aerial Vehicles". Sensors 22, nr 15 (22.07.2022): 5477. http://dx.doi.org/10.3390/s22155477.
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Recent years have witnessed rapid development and great indignation burgeoning in the unmanned aerial vehicles (UAV) field. This growth of UAV-related research contributes to several challenges, including inter-communication from vehicle to vehicle, transportation coverage, network information gathering, network interworking effectiveness, etc. Due to ease of usage, UAVs have found novel applications in various areas such as agriculture, defence, security, medicine, and observation for traffic-monitoring applications. This paper presents an innovative drone system by designing and developing a blended-wing-body (BWB)-based configuration for next-generation drone use cases. The proposed method has several benefits, including a very low interference drag, evenly distributed load inside the body, and less radar signature compared to the state-of-the-art configurations. During the entire procedure, a standard design approach was followed to optimise the BWB framework for next-generation use cases by considering the typically associated parameters such as vertical take-off and landing and drag and stability of the BWB. Extensive simulation experiments were performed to carry out a performance analysis of the proposed model in a software-based environment. To further confirm that the model design of the BWB-UAV is fit to execute the targeted missions, the real-time working environments were tested through advanced numerical simulation and focused on avoiding cost and unwanted wastages. To enhance the trustworthiness of this said computational fluid dynamics (CFD) analysis, grid convergence test-based validation was also conducted. Two different grid convergence tests were conducted on the induced velocity of the Version I UAV and equivalent stress of the Version II UAV. Finite element analysis-based computations were involved in estimating structural outcomes. Finally, the mesh quality was obtained as 0.984 out of 1. The proposed model is very cost-effective for performing a different kind of manoeuvring activities with the help of its unique design at reasonable mobility speed and hence can be modelled for high-speed-based complex next-generation use cases.
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Ogunsesan, Oluwademilade Adekunle, Mamdud Hossain i Mohamad Ghazi Droubi. "Computational fluid dynamics modelling of multiphase flows in double elbow geometries". Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 29.05.2021, 095440892110217. http://dx.doi.org/10.1177/09544089211021744.
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This study investigates the effects of elbow on the transition and development of multiphase flow using computational fluid dynamics modelling techniques. The Eulerian - Multifluid VOF model coupled with an Interfacial Area Transport Equation has been employed to simulate air-water two-phase flow in a pipe with two standard 90 degree elbows mounted in series. Turbulence effects were accounted for by the RNG k-ε model. The effects of separation distance on two-phase flow development have been studied for initial slug and churn flow regimes. Computational fluid dynamics simulation results of phase distribution and time series of void fraction fluctuations were obtained and they showed good agreement with available experimental data. The results show that for initial slug flow regime, there is no flow regime transformation upstream and downstream of the two elbows. While at initial churn flow regime, flow regime transformation occurs at different sections of the flow domain before and after the two elbows. It was noticed that irrespective of the flow regime, the amplitudes and frequencies of void fraction fluctuation become smaller as the fluid flows along the pipe. Changes in the separation distance between the two elbows have larger effects on the flow at churn flow regime.
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Cozzi, Lorenzo, Filippo Rubechini, Matteo Giovannini, Michele Marconcini, Andrea Arnone, Andrea Schneider i Pio Astrua. "Capturing Radial Mixing in Axial Compressors With Computational Fluid Dynamics". Journal of Turbomachinery 141, nr 3 (21.01.2019). http://dx.doi.org/10.1115/1.4041738.
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The current industrial standard for numerical simulations of axial compressors is the steady Reynolds-averaged Navier–Stokes (RANS) approach. Besides the well-known limitations of mixing planes, namely their inherent inability to capture the potential interaction and the wakes from the upstream blades, there is another flow feature which is lost, and which is a major accountable for the radial mixing: the transport of streamwise vorticity. Streamwise vorticity is generated for various reasons, mainly associated with secondary and tip-clearance flows. A strong link exists between the strain field associated with the vortices and the mixing augmentation: the strain field increases both the area available for mixing and the local gradients in fluid properties, which provide the driving potential for the mixing. In the rear compressor stages, due to high clearances and low aspect ratios, only accounting for the development of secondary and clearance flow structures, it is possible to properly predict the spanwise mixing. In this work, the results of steady and unsteady simulations on a heavy-duty axial compressor are compared with experimental data. Adopting an unsteady framework, the enhanced mixing in the rear stages is properly captured, in remarkable agreement with experimental distributions. On the contrary, steady analyses strongly underestimate the radial transport. It is inferred that the streamwise vorticity associated with clearance flows is a major driver of radial mixing, and restraining it by pitch-averaging the flow at mixing planes is the reason why the steady approach cannot predict the radial transport in the rear part of the compressor.
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Sayah, Haytham, Maroun Nemer, Wassim Nehmé i Denis Clodic. "Computational Fluid Dynamics Modeling of a Self-Recuperative Burner and Development of a Simplified Equivalent Radiative Model". Journal of Heat Transfer 134, nr 12 (5.10.2012). http://dx.doi.org/10.1115/1.4003756.
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The solution for dynamic modeling of reheating furnaces requires a burner model, which is simultaneously accurate and fast. Based on the fact that radiative heat transfer is the most dominant heat transfer mode in high-temperature processes, the present study develops a simplified flame representation model that can be used for dynamic simulation of heat transfer in reheating furnaces. The first part of the paper investigates, experimentally and computationally, gas combustion in an industrial burner. Experiments aim at establishing an experimental database of the burner characteristics. This database is compared with numerical simulations in order to establish a numerical model for the burner. The numerical burner model was solved using a commercial computational fluid dynamics (CFD) software (FLUENT 6.3.26). A selection of results is presented, highlighting the usefulness of CFD as a modeling tool for industrial scale burners. In the second part of the paper, a new approach called the “emissive volume approach” is established. This approach consists of replacing the burner flame by a number of emissive volumes that replicates the radiative effect of the flame. Comparisons with CFD results show a difference smaller than 1% is achieved with the emissive volume approach, while computational time is divided by 40.
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Halama, Stefan, i Hartmut Spliethoff. "Reaction Kinetics of Pressurized Entrained Flow Coal Gasification: Computational Fluid Dynamics Simulation of a 5 MW Siemens Test Gasifier". Journal of Energy Resources Technology 138, nr 4 (22.02.2016). http://dx.doi.org/10.1115/1.4032620.
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Modeling pressurized entrained flow gasification of solid fuels plays an important role in the development of integrated gasification combined cycle (IGCC) power plants and other gasification applications. A better understanding of the underlying reaction kinetics is essential for the design and optimization of entrained flow gasifiers—in particular at operating conditions relevant to large-scale industrial gasifiers. The presented computational fluid dynamics (CFD) simulations aim to predict conversion rates as well as product gas compositions in entrained flow gasifiers. The simulations are based on the software ansys fluent 15.0 and include several detailed submodels in user defined functions (UDF). In a previous publication, the developed CFD model has been validated for a Rhenish lignite against experimental data, obtained from a pilot-scale entrained flow gasifier operated at the Technische Universität München. In the presented work, the validated CFD model is applied to a Siemens test gasifier geometry. Simulation results and characteristic parameters, with focus on char gasification reactions, are analyzed in detail and provide new insights into the gasification process.
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Le, Long Thanh, Trung Nghia Tran, Hoang Kim Son Mai i Thai Son Tran. "Development of a Laminar Air Flow System for Preventing Surgical Equipment Table Infections". Science & Technology Development Journal - Engineering and Technology, 2021. http://dx.doi.org/10.32508/stdjet.v4isi2.877.
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Nowadays, the infections cause the higher patient mortality and longer time in hospitals and clinical treatment units. It requires the good quality of healthcare services. This paper presents the research in an attempt to realize a mobile laminar airflow system for preventing the contamination of airborne pathogens by protecting the surgical site area as well as the instrument table as low-cost as possible. The portable laminar airflow system and centrifugal fan are modeled by using computer-aided design (CAD) software. This system concludes a blower, UVC lamp, standard filter, high-efficiency particulate air (HEPA) filter, and instrument table. Then, the proposed device was verified through numerical simulations. Computational Fluid Dynamics (CFD) was performed to optimize the system design by examining and evaluating the results, as well as computing the aerodynamic characteristics for the system's centrifugal blower and taking fan pressure variation into account while adjusting inlet flow. As a result, sterile conditions may be created instantaneously and anyplace using this proposed laminar airflow system. The innovative layered airflow sterilizer may achieve a local Biosafety Level II in a specific area, such as an isolation room, patient bedroom, or operating room. After modeling the system, the finer mesh of centrifugal fan was carried out to ensure the accuracy of numerical simulation. There are four domains discretized in a centrifugal fan such as impeller fluid domain, volute fluid domain, inlet, and outlet fluid domain. The inlet mass flow rate strongly affects the performance of the centrifugal fan. The numerical results show that the total pressure maintained inside the blower increase as the flow rate gets larger. The results of this study provide an essential basis for optimizing system design in future investigations.
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Lorin, Samuel, Julia Madrid, Rikard Söderberg i Kristina Wärmefjord. "A New Heat Source Model for Keyhole Mode Laser Welding". Journal of Computing and Information Science in Engineering 22, nr 1 (13.07.2021). http://dx.doi.org/10.1115/1.4051122.
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Abstract Laser welding is a common technique for joining metals in many manufacturing industries. During welding, a weld gun traverses the interface of the parts to be joined causing them to melt, fuse, and solidify when the temperature decreases, thus joining the parts. Due to the heat input and the resulting melting and solidification, the parts deform causing residual distortion and residual stresses. To assure the geometrical and functional quality of the product, computational welding mechanics (CWM) is often employed in the design phase to predict the outcome of different design proposals. Furthermore, CWM can be used to design the welding process with the objective of assuring the quality of the weld. However, welding is a complex multiphysical process including the weld pool flow, microstructure dynamics, and structural mechanics. In a design process, it is typically not feasible, for example, to employ fluid simulation of the weld pool in order to predict deformation of a welded assembly, especially if a set of design proposals is under investigation. This is because of the high resolution needed for these fluid simulations in combination with challenges to couple fluid simulation with structural simulation. Instead, what is used is a heat source that emulates the heat input from the melt pool. An example of a heat source is the standard doubled ellipsoid. This heat source has been efficiently used for a large number of welding simulation. However, standard heat sources are typically not flexible enough to capture the fusion zone for deep keyhole mode laser welding. In this study, we presented a new heat source model for keyhole mode laser welding. In an industrial case study, a number of bead-on-plate welds have been employed to compare standard weld heat sources and develop the new heat source model. The proposed heat source is based on a combination of standard heat sources. From this study, it was concluded that the standard heat sources could not predict the observed melted zone for certain industrial application while the new heat source was able to do so. Therefore, the proposed heat source model can be employed to model keyhole mode laser welding, which enables welding simulation of a set of design proposals during the design process in a larger number of industrial cases.