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Urban, Ondřej, Michaela Kurková, and Pavel Rudolf. "Application of Computer Graphics Flow Visualization Methods in Vortex Rope Investigations." Energies 14, no. 3 (January 26, 2021): 623. http://dx.doi.org/10.3390/en14030623.
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Computer graphics visualization techniques for application on data from Computational Fluid Dynamics (CFD) simulations of the vortex rope, a phenomenon present in hydraulic turbines operating in off-design conditions, were devised. This included not only objects for visualization (what to visualize) but also methods of the visualization itself (how to do it). By means of advanced methods based particularly on volume rendering of Eulerian fields in combination with Lagrangian objects, various phenomena were captured, such as the motion of the vortex rope or the backflow zone. The data came from simulations using a scale-resolving hybrid turbulence model, the Stress-Blended Eddy Simulation. In such detailed simulations and other applications involving complex three-dimensional structures, proper visualization methods are needed to leverage the content captured in the resultant data.
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Summers, Kenneth L., Thomas Preston Caudell, Kathryn Berkbigler, Brian Bush, Kei Davis, and Steve Smith. "Graph Visualization for the Analysis of the Structure and Dynamics of Extreme-Scale Supercomputers." Information Visualization 3, no. 3 (July 8, 2004): 209–22. http://dx.doi.org/10.1057/palgrave.ivs.9500079.
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We are exploring the development and application of information visualization techniques for the analysis of new massively parallel supercomputer architectures. Modern supercomputers typically comprise very large clusters of commodity SMPs interconnected by possibly dense and often non-standard networks. The scale, complexity, and inherent non-locality of the structure and dynamics of this hardware, and the operating systems and applications distributed over them, challenge traditional analysis methods. As part of the á la carte (A Los Alamos Computer Architecture Toolkit for Extreme-Scale Architecture Simulation) team at Los Alamos National Laboratory, who are simulating these new architectures, we are exploring advanced visualization techniques and creating tools to enhance analysis of these simulations with intuitive three-dimensional representations and interfaces. This work complements existing and emerging algorithmic analysis tools. In this paper, we give background on the problem domain, a description of a prototypical computer architecture of interest (on the order of 10,000 processors connected by a quaternary fat-tree communications network), and a presentation of three classes of visualizations that clearly display the switching fabric and the flow of information in the interconnecting network.
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Almohammadi, Khaled Mohammad. "Smooth Particle Hydrodynamic and URAN Visualization of Multiphase Flow." Defect and Diffusion Forum 399 (February 2020): 87–91. http://dx.doi.org/10.4028/www.scientific.net/ddf.399.87.
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Significant research is being conducted in the simulation of fluid flows due to the increase in employing the physics of the fluid flow to either commercial, in-house or open source codes. The analysis of the fluid flow is mainly based on the Lagrangian or the Eulerian approach. Many of the simulation codes employ the Eulerian approach due to its simplicity. These codes are based on several numerical techniques and yet few benchmarks have been conducted. However, the codes which employ the Lagrangian approach seem to be promising and may accurately simulate fluid flow phenomena. In this paper, a comparative analysis of the Lagrangian and Eulerian approach is investigated for a water droplet in a tank. The velocity field and the total pressure of the fluid are generated for the simulation by employing Ansys Fluent for the Eulerian approach and DualPhysics for the Lagrangian approach. The fluid structure and the fluid flow development are compared in order to assess the capability of each approaches in analysing the investigated fluid flow. This study may play a significant role on the importance of employing the Lagrangian approach for fluid flows where complex fluid structure occurs.
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Jiao, Yun, and Chengpeng Wang. "Visualization of separation and reattachment in an incident shock-induced interaction." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 235, no. 12 (March 11, 2021): 1706–16. http://dx.doi.org/10.1177/0954410020983495.
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An experimental study is conducted on the qualitative visualization of the flow field in separation and reattachment flows induced by an incident shock interaction by several techniques including shear-sensitive liquid crystal coating (SSLCC), oil flow, schlieren, and numerical simulation. The incident shock wave is generated by a wedge in a Mach 2.7 duct flow, where the strength of the interaction is varied from weak to moderate by changing the angle of attack α of the wedge from 8° and 10° to 12°. The stagnation pressure upstream was set to approximately 607.9 kPa. The SSLCC technique was used to visualize the surface flow characteristics and analyze the surface shear stress fields induced by the initial incident shock wave over the bottom wall and sidewall experimentally which resolution is 3500 × 200 pixels, and the numerical simulation was also performed as the supplement for a clearer understanding to the flow field. As a result, surface shear stress over the bottom wall was visualized qualitatively by SSLCC images, and flow features such as separation/reattachment and the variations of position/size of separation bubble with wedge angle were successfully distinguished. Furthermore, analysis of shear stress trend over the bottom wall by a hue value curve indicated that the relative magnitude of shear stress increased significantly downstream of the separation bubble compared with that upstream. The variation trend of shear stress was consistent with the numerical simulation results, and the error of separation position was less than 2 mm. Finally, the three-dimensional schematic of incident shock-induced interaction has been achieved by qualitative summary by multiple techniques, including SSLCC, oil flow, schlieren, and numerical simulation.
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Banaś, Michał, Piotr Antoniak, Lubomir Marciniak, and Jarosław Stryczek. "Visualization of flow phenomena in hydraulic throttle valves of plastics." MATEC Web of Conferences 211 (2018): 19001. http://dx.doi.org/10.1051/matecconf/201821119001.
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Using elements made of plastics in hydraulic drives and controls encounters problems, for example related to strength. However, the advantage of solutions with plastics manifests itself, among others in possibility of shaping hydraulic elements in accordance with the assumed requirements. The use of additive manufacturing techniques allows us to make plastic parts with shapes that are unattainable for steel parts. The authors have attempted to determine the influence of the shape of the closing element on the phenomena of flow through the throttling gap in the hydraulic throttle valve. They chose three poppets of different shapes and carried out flow simulations using CFD. They compared simulation results in the form of flow velocity field in the valve chamber with observations obtained with the Particle Image Velocimetry (PIV) technique. In visualization tests, a throttle valve made of transparent materials and markers in a form of air bubbles were used. The tests confirmed the possibility of using air bubbles as markers of the PIV method at low pressure. The presented conclusions indicate the need for further modification of the shape of the closing element as well as of the design of the valve body.
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Rozmanov, Dmitri, Svetlana Baoukina, and D. Peter Tieleman. "Density based visualization for molecular simulation." Faraday Discuss. 169 (2014): 225–43. http://dx.doi.org/10.1039/c3fd00124e.
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Molecular visualization of structural information obtained from computer simulations is an important part of research work flow. A good visualization technique should be capable of eliminating redundant information and highlight important effects clarifying the key phenomena in the system. Current methods of presenting structural data are mostly limited to variants of the traditional ball-and-stick representation. This approach becomes less attractive when very large biological systems are simulated at microsecond timescales, and is less effective when coarse-grained models are used. Real time rendering of such large systems becomes a difficult task; the amount of information in one single frame of a simulation trajectory is enormous given the large number of particles; at the same time, each structure contains information about one configurational point of the system and no information about statistical weight of this specific configuration. In this paper we report a novel visualization technique based on spatial particle densities. The atomic densities are sampled on a high resolution 3-dimensional grid along a relatively short molecular dynamics trajectory using hundreds of configurations. The density information is then analyzed and visualized using the open-source ParaView software. The performance and capability of the method are demonstrated on two large systems simulated with the MARTINI coarse-grained force field: a lipid nanoparticle for delivering siRNA molecules and monolayers with a complex composition under conditions that induce monolayer collapse.
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Itamura, M., N. Yamamoto, E. Niyama, and K. Anzai. "Application of the flow visualization technique and flow simulation to diecasting flow analysis." International Journal of Cast Metals Research 9, no. 3 (September 1996): 139–43. http://dx.doi.org/10.1080/13640461.1996.11819653.
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Sauer, Franz, Yubo Zhang, Weixing Wang, Stephane Ethier, and Kwan-Liu Ma. "Visualization Techniques for Studying Large-Scale Flow Fields from Fusion Simulations." Computing in Science & Engineering 18, no. 2 (March 2016): 68–77. http://dx.doi.org/10.1109/mcse.2015.107.
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Yanev, A. S., Gustavo R. Dias, and António M. Cunha. "Visualization of Injection Moulding Process." Materials Science Forum 587-588 (June 2008): 716–20. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.716.
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A special tool-transparent mould designed to visualize the melt flow inside the cavity is used in this research. The aim of the work is to assess the polymer melt behavior under different processing conditions-close to industrial, in conventional and two materials non-conventional injection moulding techniques. The mould is designed with two injection locations and has possibility to change the geometry of the cavity in order to investigate the melt behavior in differently shaped cavities. Visual access in the mould is allowed by the sapphire windows, surrounding the cavity. For image acquisition a high speed video camera NAC 1000 is used. Materials used in the research are three polypropylenes with different flow index. Results are obtained for conventional injection moulding, two material monosandwich and two material biinjection moulding. Apart from visualization, instrumentation of the mould allows to be obtained PT data for each processing condition. Results from conventional injection moulding are compared with MPI5.0 simulations.
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Diab, Samir, and Dimitrios I. Gerogiorgis. "Design Space Identification and Visualization for Continuous Pharmaceutical Manufacturing." Pharmaceutics 12, no. 3 (March 5, 2020): 235. http://dx.doi.org/10.3390/pharmaceutics12030235.
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Progress in continuous flow chemistry over the past two decades has facilitated significant developments in the flow synthesis of a wide variety of Active Pharmaceutical Ingredients (APIs), the foundation of Continuous Pharmaceutical Manufacturing (CPM), which has gained interest for its potential to reduce material usage, energy and costs and the ability to access novel processing windows that would be otherwise hazardous if operated via traditional batch techniques. Design space investigation of manufacturing processes is a useful task in elucidating attainable regions of process performance and product quality attributes that can allow insight into process design and optimization prior to costly experimental campaigns and pilot plant studies. This study discusses recent demonstrations from the literature on design space investigation and visualization for continuous API production and highlights attainable regions of recoveries, material efficiencies, flowsheet complexity and cost components for upstream (reaction + separation) via modeling, simulation and nonlinear optimization, providing insight into optimal CPM operation.
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Pieprzyca, J., P. Warzecha, T. Merder, and M. Warzecha. "Experimental Methods of Validation for Numerical Simulation Results on Steel Flow through Tundish." Archives of Metallurgy and Materials 61, no. 4 (December 1, 2016): 2057–60. http://dx.doi.org/10.1515/amm-2016-0331.
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Abstract The article presents experimental results on the impact of tundish flow regulator influencing the liquid steel flow course. The research was conducted based on the hybrid modelling methods understood as a complementary use of Computational Fluid Dynamics (CFD) methods and physical modelling. Dynamic development of numerical simulation techniques and accessibility to highly advanced and specialized software causes the fact that these techniques are commonly used for solving problems related to liquid flows by using analytical methods. Whereas, physical modelling is an important cognitive tool in the field of empirical identification of these phenomena. This allows for peer review and specification of the researched problems. By exploiting these relationships, a comparison of the obtained results was performed in the form of residence time distribution (RTD) curves and visualization of particular types of liquid steel flow distribution zones in the investigated tundish.
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Bouhanguel, Ala, Philippe Desevaux, Yannick Bailly, and Laurent Girardot. "Flow Velocity Investigation by Particle Image Velocimetry in Supersonic Air Ejector." Applied Mechanics and Materials 232 (November 2012): 256–60. http://dx.doi.org/10.4028/www.scientific.net/amm.232.256.
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Ejectors are devices usually made of two convergent/divergent coaxial nozzles which are used to convert pressure energy into kinetic energy. These devices involve very complex phenomena which strongly affect their performance. Flow visualization methods are often used to provide precious information as for the nature of the flow within the ejectors and the comprehension of the physical phenomena encountered. Unfortunately, the visualization methods used successfully until now in these systems are primarily qualitative techniques. Some attempts at quantitative flow visualization by Particle Image Velocimetry have been carried out in quite specific applications but with mitigated results due to the complicated conditions of investigation. The objective of this paper is to present an attempt at PIV measurements in a supersonic air ejector. Several ejector operating conditions and flow seeding methods are taken into consideration. The velocity fields obtained are compared with CFD simulations of the flow and allow the rigorous validation of numerical models.
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Shutts, Glenn, Thomas Allen, and Judith Berner. "Stochastic parametrization of multiscale processes using a dual-grid approach." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1875 (April 29, 2008): 2623–39. http://dx.doi.org/10.1098/rsta.2008.0035.
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Some speculative proposals are made for extending current stochastic sub-gridscale parametrization methods using the techniques adopted from the field of computer graphics and flow visualization. The idea is to emulate sub-filter-scale physical process organization and time evolution on a fine grid and couple the implied coarse-grained tendencies with a forecast model. A two-way interaction is envisaged so that fine-grid physics (e.g. deep convective clouds) responds to forecast model fields. The fine-grid model may be as simple as a two-dimensional cellular automaton or as computationally demanding as a cloud-resolving model similar to the coupling strategy envisaged in ‘super-parametrization’. Computer codes used in computer games and visualization software illustrate the potential for cheap but realistic simulation where emphasis is placed on algorithmic stability and visual realism rather than pointwise accuracy in a predictive sense. In an ensemble prediction context, a computationally cheap technique would be essential and some possibilities are outlined. An idealized proof-of-concept simulation is described, which highlights technical problems such as the nature of the coupling.
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Höller, Mark, Kay-M. Otto, Uwe Klose, Samuel Groeschel, and Hans-H. Ehricke. "Fiber Visualization with LIC Maps Using Multidirectional Anisotropic Glyph Samples." International Journal of Biomedical Imaging 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/401819.
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Line integral convolution (LIC) is used as a texture-based technique in computer graphics for flow field visualization. In diffusion tensor imaging (DTI), LIC bridges the gap between local approaches, for example directionally encoded fractional anisotropy mapping and techniques analyzing global relationships between brain regions, such as streamline tracking. In this paper an advancement of a previously published multikernel LIC approach for high angular resolution diffusion imaging visualization is proposed: a novel sampling scheme is developed to generate anisotropic glyph samples that can be used as an input pattern to the LIC algorithm. Multicylindrical glyph samples, derived from fiber orientation distribution (FOD) functions, are used, which provide a method for anisotropic packing along integrated fiber lines controlled by a uniform random algorithm. This allows two- and three-dimensional LIC maps to be generated, depicting fiber structures with excellent contrast, even in regions of crossing and branching fibers. Furthermore, a color-coding model for the fused visualization of slices from T1 datasets together with directionally encoded LIC maps is proposed. The methodology is evaluated by a simulation study with a synthetic dataset, representing crossing and bending fibers. In addition, results fromin vivostudies with a healthy volunteer and a brain tumor patient are presented to demonstrate the method's practicality.
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Jahanbakhsh, Amir, Krystian L. Wlodarczyk, Duncan P. Hand, Robert R. J. Maier, and M. Mercedes Maroto-Valer. "Review of Microfluidic Devices and Imaging Techniques for Fluid Flow Study in Porous Geomaterials." Sensors 20, no. 14 (July 20, 2020): 4030. http://dx.doi.org/10.3390/s20144030.
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Understanding transport phenomena and governing mechanisms of different physical and chemical processes in porous media has been a critical research area for decades. Correlating fluid flow behaviour at the micro-scale with macro-scale parameters, such as relative permeability and capillary pressure, is key to understanding the processes governing subsurface systems, and this in turn allows us to improve the accuracy of modelling and simulations of transport phenomena at a large scale. Over the last two decades, there have been significant developments in our understanding of pore-scale processes and modelling of complex underground systems. Microfluidic devices (micromodels) and imaging techniques, as facilitators to link experimental observations to simulation, have greatly contributed to these achievements. Although several reviews exist covering separately advances in one of these two areas, we present here a detailed review integrating recent advances and applications in both micromodels and imaging techniques. This includes a comprehensive analysis of critical aspects of fabrication techniques of micromodels, and the most recent advances such as embedding fibre optic sensors in micromodels for research applications. To complete the analysis of visualization techniques, we have thoroughly reviewed the most applicable imaging techniques in the area of geoscience and geo-energy. Moreover, the integration of microfluidic devices and imaging techniques was highlighted as appropriate. In this review, we focus particularly on four prominent yet very wide application areas, namely “fluid flow in porous media”, “flow in heterogeneous rocks and fractures”, “reactive transport, solute and colloid transport”, and finally “porous media characterization”. In summary, this review provides an in-depth analysis of micromodels and imaging techniques that can help to guide future research in the in-situ visualization of fluid flow in porous media.
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Liu, Qingsheng, Jie Ouyang, Zhijun Liu, and Wuming Li. "Visualization and simulation of filling process of simultaneous co-injection molding based on level set method." Journal of Polymer Engineering 35, no. 9 (November 1, 2015): 813–27. http://dx.doi.org/10.1515/polyeng-2014-0339.
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Abstract Co-injection molding (CIM) is an advanced technology which was developed to meet quality requirements and to reduce the material cost. Theoretical investigations concerning it are very limited, especially for simultaneous CIM. The interactions of air, skin and core polymer melt in the process are very complex, which makes it more challenging to simulate free surface flows in the mold. Thus, this article presents a mathematical model for it. The extended Pom-Pom (XPP) model is selected to predict the viscoelastic behavior of polymer melt. The free surface is captured by the level set method. The article vividly shows the simultaneous CIM process by means of a visual numerical simulation technique. Both two-dimensional (2D) and 3D examples are presented to validate the model and illustrate its capabilities. The 3D flow behaviors of simultaneous CIM process are hard to predict numerically. To our knowledge, this is the first attempt at simulating melt flow behaviors in 3D simultaneous CIM based on the XPP constitutive equation and visual technique. The numerical results are in good agreement with the available experiment results, which establish the capability of the multiphase flow model presented in this article to simulate the flow behaviors of polymer melt in simultaneous CIM process.
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Park, Cheol Woo, In Je Baek, and Jong Hwan Yoon. "An Experimental Study on the Flow Structure inside a Display Cooler Using PIV Techniques." Key Engineering Materials 326-328 (December 2006): 167–70. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.167.
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In the present study, the flow structure inside the refrigerating compartment of a scaleddown display cooler model was investigated experimentally using the particle image velocimetry (PIV) method, which is a reliable velocity field measurement technique. In addition, we also carried out flow visualization and computer simulations regarding the movements of thermo-fluid inside a display cooler. As a result, the velocity field measurement shows a large scale vortical flow structure inside the refrigerating compartment due to the entrained flow, thus penetrating a base plate through the open inlet gap.
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Al-Kayiem, Hussain H. "Visualization of Flow Field and Wake over Clean and Under-Loaded Wings." Applied Mechanics and Materials 629 (October 2014): 24–29. http://dx.doi.org/10.4028/www.scientific.net/amm.629.24.
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Experimental details of the flow field and wake over airfoils and 2-D wings are time and cost consumption. In this study, the flow visualization technique was adopted to investigate the flow field surrounding NACA4412 airfoil. The investigations were carried out in smoke tunnel, operating at low Reynolds number in a range of 105. The airfoil was tested in two operational cases: first as clean wing and the second as under-loaded wing by attached missile model. The experiments were conducted at various angles of attack as 00, 50,100, 150and 200. It was found that the under-load of external body under the wing is influencing the flow structure over the wing. Also, the wake after the external body is swirling, leading to very complicated wake interaction. The results from the work can support the numerical simulation and the prediction of the laminar to turbulent transition and the separation and wake interaction of high lift airfoil flow fields.
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Zhong, Qi, Wen Hua Zeng, Xiao Yang Huang, and Bo Liang Wang. "Numerical Simulation of the Dynamics of Heart Valves: A Literature Review." Applied Mechanics and Materials 444-445 (October 2013): 1211–17. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1211.
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Imaging techniques allow the visualization of the heart valves, but do not yields any information regarding the load applied to the heart valve information that provides key clues to the cause of valve deterioration. Numerical simulation, which is able to replicate and understand the dynamics of the valve, would benefit studies on heart valves surgical repair and prostheses design. Modeling and simulation of heart valves dynamics is a challenging biomechanical problem. Many researchers have taken various approaches to model the heart valve. But systematical categorization and development tendency of their research have never been discussed before. This paper reviews their models and divides them into wet models or dry models, in the light of whether considering blood flow and valve interaction. These simulations also can be categorized as native heart valve or artificial heart valve simulation by a different model prototype. The critical issues for future research are presented.
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Bondarenko, G. A., V. N. Baga, and I. A. Bashlak. "Flow Simulation in a Labyrinth Seal." Applied Mechanics and Materials 630 (September 2014): 234–39. http://dx.doi.org/10.4028/www.scientific.net/amm.630.234.
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The paper studies the labyrinth seals of centrifugal compressor profit-proved stages using modern methods of numerical and physical modeling of the centrifugal compressor stages. A series of studies of the effect of operational and geometrical parameters on the maze, namely the quantities of the packed differential pressure, speed, fluid, geometric parameters of the seal, the magnitude of the eccentricity and radial clearance swirl flow at the inlet of a seal, etc. The technique of physical modeling seal has been specified. Research was conducted in two phases: numerical simulation using complex software Flow Vision and receiving data on a universal test bench to study the labyrinth seals.. A three-dimensional model of the labyrinth seal has been created, its verification by "known data has been held.. Integral characteristics in the form of distribution of flow velocities and pressures, flow visualization were obtained. Results of studies made it possible to refine the workflow and introduce amendments to the known calculation formula for a more accurate calculation of leakage through the seal, subject to a number of additional factors that were not previously taken into account
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Regi, Francesco, Patrick Guerrier, Yang Zhang, and Guido Tosello. "Experimental Characterization and Simulation of Thermoplastic Polymer Flow Hesitation in Thin-Wall Injection Molding Using Direct In-Mold Visualization Technique." Micromachines 11, no. 4 (April 19, 2020): 428. http://dx.doi.org/10.3390/mi11040428.
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A special mold provided with a glass window was used in order to directly evaluate the flow progression during the filling phase of the injection molding process in a thin-wall cavity and to validate the simulation of the process with particular focus on the hesitation effect. The flow of the polymer was recorded at 500 frames per second using a high-speed camera (HSC). Two unfilled thermoplastic polymers, acrylonitrile butadiene styrene (ABS), and polypropylene (PP), were used to fill two different 50 mm × 18 mm staircase geometry cavities, which were specifically designed to evaluate the hesitation effect with thicknesses of 1500, 1250, 1000, 750, 500 µm (cavity insert no. 1) and 1500, 1200, 900, 600, 300 µm (cavity insert no. 2). In addition to the video recordings, the simulations were validated using the timings and the data obtained by three pressure sensors and two thermocouples located in the cavity. For each injection cycle recorded on camera the machine data were collected to carefully implement the correct boundary conditions in the simulations. The analysis of the video recordings highlighted that flow progression and hesitation were mainly influenced not only by the thickness, but also by the velocity and the material type. The simulation results were in relatively good agreement with the experiments in terms of flow pattern and progression. Filling times were predicted with an average relative error deviation of 2.5% throughout all the section thicknesses of the cavity. Lower accuracies in terms of both filling times and injection pressure were observed at increasingly thinner sections.
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KOBAYASHI, Takahiro, and Toyokazu UCHIDA. "1302 The study on evaluation technique for gas substitution nozzle flow by visualization and simulation(2)." Proceedings of the Fluids engineering conference 2006 (2006): _1302–1_—_1302–4_. http://dx.doi.org/10.1299/jsmefed.2006._1302-1_.
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KOBAYASHI, Takahiro, and Toyokazu UCHIDA. "1302 The study on evaluation technique for gas substitution nozzle flow by visualization and simulation(1)." Proceedings of the Fluids engineering conference 2006 (2006): _1302—a_. http://dx.doi.org/10.1299/jsmefed.2006._1302-a_.
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Ankit, K., M. Selzer, and B. Nestler. "Three-dimensional phase-field study of crack-seal microstructures – insights from innovative post-processing techniques." Geoscientific Model Development Discussions 7, no. 1 (January 17, 2014): 631–58. http://dx.doi.org/10.5194/gmdd-7-631-2014.
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Abstract. Numerical simulations of vein evolution contribute to a better understanding of processes involved in their formation and possess the potential to provide invaluable insights into the rock deformation history and fluid flow pathways. The primary aim of the present article is to investigate the influence of a "realistic" boundary condition, i.e. an algorithmically generated "fractal" surface, on the vein evolution in 3-D using a thermodynamically consistent approach, while explaining the benefits of accounting for an extra dimensionality. The 3-D simulation results are supplemented by innovative numerical post-processing and advanced visualization techniques. The new methodologies to measure the tracking efficiency demonstrate the importance of accounting the temporal evolution; no such information is usually accessible in field studies and notoriously difficult to obtain from laboratory experiments as well. The grain growth statistics obtained by numerically post-processing the 3-D computational microstructures explain the pinning mechanism which leads to arrest of grain boundaries/multi-junctions by crack peaks, thereby, enhancing the tracking behavior.
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Ho, W. H., I. J. Tshimanga, M. N. Ngoepe, M. C. Jermy, and P. H. Geoghegan. "Evaluation of a Desktop 3D Printed Rigid Refractive-Indexed-Matched Flow Phantom for PIV Measurements on Cerebral Aneurysms." Cardiovascular Engineering and Technology 11, no. 1 (December 9, 2019): 14–23. http://dx.doi.org/10.1007/s13239-019-00444-z.
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Abstract Purpose Fabrication of a suitable flow model or phantom is critical to the study of biomedical fluid dynamics using optical flow visualization and measurement methods. The main difficulties arise from the optical properties of the model material, accuracy of the geometry and ease of fabrication. Methods Conventionally an investment casting method has been used, but recently advancements in additive manufacturing techniques such as 3D printing have allowed the flow model to be printed directly with minimal post-processing steps. This study presents results of an investigation into the feasibility of fabrication of such models suitable for particle image velocimetry (PIV) using a common 3D printing Stereolithography process and photopolymer resin. Results An idealised geometry of a cerebral aneurysm was printed to demonstrate its applicability for PIV experimentation. The material was shown to have a refractive index of 1.51, which can be refractive matched with a mixture of de-ionised water with ammonium thiocyanate (NH4SCN). The images were of a quality that after applying common PIV pre-processing techniques and a PIV cross-correlation algorithm, the results produced were consistent within the aneurysm when compared to previous studies. Conclusions This study presents an alternative low-cost option for 3D printing of a flow phantom suitable for flow visualization simulations. The use of 3D printed flow phantoms reduces the complexity, time and effort required compared to conventional investment casting methods by removing the necessity of a multi-part process required with investment casting techniques.
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Yang, Yi Tao, Heng Hua Zhang, and Guang Jie Shao. "Application of Computer Simulation in Developing Automotive Parts of Al Alloy by Using Semi-Solid Die Cast Process." Solid State Phenomena 116-117 (October 2006): 630–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.630.
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To aid the optimizing design of filling system, computer simulation technique is introduced to predict injection-forming process and to protect defects during trial manufacture of automotive parts by using semi-solid die cast process. By comparing formed appearance of parts in experiments and that in simulations, and observing the relationship between internal defects inspected by X-ray and flow field obtained in simulation, it is indicated that there are quite good agreements between simulation and experiment, right predictions for cast defects resulting from filling process can be made and improving direction is proposed. The realization of numerical visualization for filling process of high speed during semi-solid die cast process will play an important role in optimizing technology plan and process.
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Johansson, Arne V., P. Henrik Alfredsson, and John Kim. "Evolution and dynamics of shear-layer structures in near-wall turbulence." Journal of Fluid Mechanics 224 (March 1991): 579–99. http://dx.doi.org/10.1017/s002211209100188x.
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Near-wall flow structures in turbulent shear flows are analysed, with particular emphasis on the study of their space–time evolution and connection to turbulence production. The results are obtained from investigation of a database generated from direct numerical simulation of turbulent channel flow at a Reynolds number of 180 based on half-channel width and friction velocity. New light is shed on problems associated with conditional sampling techniques, together with methods to improve these techniques, for use both in physical and numerical experiments. The results clearly indicate that earlier conceptual models of the processes associated with near-wall turbulence production, based on flow visualization and probe measurements need to be modified. For instance, the development of asymmetry in the spanwise direction seems to be an important element in the evolution of near-wall structures in general, and for shear layers in particular. The inhibition of spanwise motion of the near-wall streaky pattern may be the primary reason for the ability of small longitudinal riblets to reduce turbulent skin friction below the value for a flat surface.
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Sung, Hyung Jin, Young Nam Kim, and Jae Min Hyun. "Discrete Vortex Simulation of Pulsating Flow Behind a Normal Plate." Journal of Fluids Engineering 116, no. 4 (December 1, 1994): 862–69. http://dx.doi.org/10.1115/1.2911862.
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A numerical study is made of the separated flow behind a flat plate. The plate is placed normal to the direction of the approach flow. The oncoming freestream velocity contains a pulsating part, U∞ = U0(1 + A0cosfpt). The temporal behavior of vortex shedding patterns is scrutinized over broad ranges of the two externally specified parameters, i.e., the pulsation amplitude (A0≤ 0.6), and the dimensionless pulsation frequency, (fp≤0.32). A version of the discrete vortex method is utilized. The variable-position nascent vortex technique is applied, and it proves to be adequate for pulsating approach flows. The numerical results clearly capture the existence of lock-on when fp exceeds a threshold value. The modulation of vorticity shedding is also detected when fp is reasonably low. The influence of A0 on the flow characteristics is examined in detail. As A0 increases to a moderate value (e.g., A0≤0.6), an appreciable broadening is seen of the range of fp for which lock-on occurs. Based on the numerical results, three characteristic flow modes in the wakes are identified. These findings are qualitatively consistent with the existing flow-visualization studies for a cylinder.
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Urbahs, Aleksandrs, Sudip Das, Shravan Koundinya Vutukuru, and Kristīne Carjova. "Investigation of Flow Field Around the Pointed Cowl Air Intake at Mach 2.0." Transport and Aerospace Engineering 5, no. 1 (December 1, 2017): 75–82. http://dx.doi.org/10.1515/tae-2017-0021.
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Abstract Experiments and computational studies were carried out to get an understanding of the flow field around a rectangular supersonic intake with pointed cowl shape. Experiments include quantitative pressure measurements and flow visualization studies by using schlieren techniques. The effects of the presence of various cowl shapes on ramp surface have been obtained computationally at Mach 2.0. The experiments were carried out only for the pointed cowl. Schlieren Photographs were taken. Three-Dimensional simulations were made by using FLUENT at supersonic speed. The details of the experiments and computations are discussed.
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KOSTER, J. N., T. SEIDEL, and R. DEREBAIL. "A radioscopic technique to study convective fluid dynamics in opaque liquid metals." Journal of Fluid Mechanics 343 (July 25, 1997): 29–41. http://dx.doi.org/10.1017/s0022112097005909.
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Experimental verification of theoretical investigations into the behaviour of liquid metal convective flows is required to validate analytical models and numerical simulation codes. A real-time radioscopic density visualization system has been developed and is beginning to provide useful data. The X-ray facility for studying opaque low-Prandtl-number fluid flow is described. Density changes as low as 10−3 g cm−3 can be visualized by careful control of scatter radiation. The new capability is demonstrated with natural convection benchmark experiments in a narrow vertical layer of gallium melt of aspect ratio A=1.4. The density field in that cell is three-dimensional. Good agreement between calculations and experiments is obtained. Experiments with solidification are provided for further theoretical use.
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Yang, Ho Dong, and Yool Kwon Oh. "A Study on Melting Phenomena and Enhanced Heat Transfer of Phase Change Material by Ultrasonic Vibrations." Key Engineering Materials 345-346 (August 2007): 889–92. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.889.
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This study focused on observing the melting phenomena and investigated a principle factor of enhanced heat transfer in phase change material when the ultrasonic vibrations were applied during the melting process. For visualization, particle image velocimetry and thermal-vision camera for observing the flow phenomenon was used. Also, experiments were performed to obtain the experimental results such as melting time and temperature distribution. Besides, structural vibration simulator which is applying a coupled finite element-boundary element method (Coupled FE-BEM) was used for calculation of acoustic pressure occurred by ultrasonic vibrations in liquid region. The results of experimental and numerical observations show that acoustic streaming induced by ultrasonic vibrations is one of the prime effects acoustically enhanced phase change heat transfer and help to accelerate the melting of phase change material. Also, the application technique of visualization and computational simulation introduced in this study is very useful and important to analyze the mechanical behavior of material in a fast fluid dynamic or acoustic field.
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Chavent, Matthieu, Tyler Reddy, Joseph Goose, Anna Caroline E. Dahl, John E. Stone, Bruno Jobard, and Mark S. P. Sansom. "Methodologies for the analysis of instantaneous lipid diffusion in md simulations of large membrane systems." Faraday Discuss. 169 (2014): 455–75. http://dx.doi.org/10.1039/c3fd00145h.
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Interactions between lipids and membrane proteins play a key role in determining the nanoscale dynamic and structural properties of biological membranes. Molecular dynamics (MD) simulations provide a valuable tool for studying membrane models, complementing experimental approaches. It is now possible to simulate large membrane systems, such as simplified models of bacterial and viral envelope membranes. Consequently, there is a pressing need to develop tools to visualize and quantify the dynamics of these immense systems, which typically comprise millions of particles. To tackle this issue, we have developed visual and quantitative analyses of molecular positions and their velocity field using path line, vector field and streamline techniques. This allows us to highlight large, transient flow-like movements of lipids and to better understand crowding within the lipid bilayer. The current study focuses on visualization and analysis of lipid dynamics. However, the methods are flexible and can be readily applied to e.g. proteins and nanoparticles within large complex membranes. The protocols developed here are readily accessible both as a plugin for the molecular visualization program VMD and as a module for the MDAnalysis library.
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Suzuki, Satomi, Dave Stern, and Tom Manzocchi. "The Use of Association-Rule Mining and High-Dimensional Visualization To Explore the Impact of Geological Features on Dynamic-Flow Behavior." SPE Journal 21, no. 06 (September 29, 2016): 1996–2009. http://dx.doi.org/10.2118/174774-pa.
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Summary Because of computational advances in reservoir simulation with high-performance computing, it is now possible to simulate more than thousands of reservoir-simulation cases in a practical time frame. This opens a new avenue to reservoir-simulation studies, enabling exhaustive exploration of subsurface uncertainty and development/depletion options. However, analyzing the results of a large number of simulation cases still remains a challenging and overwhelming task. We propose a new method that enables the efficient analysis of massive reservoir-simulation results, often consisting of thousands of cases, by discovering interesting patterns of relationships among variables in large data sets. The method uses a well-known data-mining method, called association-rule mining, together with a high-dimensional visualization technique. We demonstrate the capability of the proposed method by using it to analyze the reservoir-simulation results from the Sensitivity Analysis of the Impact of Geological Uncertainty on Production (SAIGUP) project, which is an interdisciplinary reservoir-modeling project carried out earlier by Manzocchi et al. (2008a). To investigate the influence of geological features on oil recovery in shallow marine reservoirs, numerous reservoir models were built and flow-simulated in the SAIGUP project. In this paper, we analyze the simulation results from an ensemble of 9,072 models, which cover all possible combinations of several structural and sedimentological parameters individually varied to describe geological uncertainty. To be able to analyze the simulation results from such exhaustive sampling from high-dimensional model parameter space, it is crucial to efficiently decompose complex interactions between model parameters and to discover hidden impacts on flow response. By coupling the association-rule mining algorithm and high-dimensional visualization, such interactions and impacts are rapidly extracted and visualized in such a way that engineers and geoscientists can interpret meaningful sensitivities “at a glance.” This methodology provides a novel way to rapidly interpret flow response from a large ensemble of reservoir models without being overwhelmed by massive data.
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Zhang, Xinxin, Jianming Peng, Jingqing Chen, Kun Bo, Kun Yin, and Dongyu Wu. "The effect of actuator parameters on the performance of a liquid-jet hammer associated with its jet behavior." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 231, no. 14 (December 26, 2016): 2610–20. http://dx.doi.org/10.1177/0954406216685350.
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Bi-stable fluidic amplifier containing no moving parts was used for switching fluid flow passing through it into an actuator in a liquid-jet hammer. So far, there has been no design basis for developing a liquid-jet hammer with high performance. To provide a guidance, this paper elaborates on the computational fluid dynamics simulation method for investigating the effect of actuator parameters on the performance of a liquid-jet hammer associated with its jet behavior. Given that couple mechanism exists between the flow field in the bi-stable fluidic amplifier and the actuator, dynamic mesh technique and a user-defined function written in C programming language were used to update the mesh in the simulations. Two evaluation criteria—pressure recovery and flux utilization ratio—for a liquid-jet hammer were used in this study. Experimental tests were conducted to verify the simulation results, by which the accuracy and reliability of this computational fluid dynamics simulation method was proved. Besides, comprehensive analysis of the flow behavior in the fluidic amplifier of a liquid-jet hammer was performed by the use of computational fluid dynamics visualization method.
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Doorly, D. J., and M. L. G. Oldfield. "Simulation of the Effects of Shock Wave Passing on a Turbine Rotor Blade." Journal of Engineering for Gas Turbines and Power 107, no. 4 (October 1, 1985): 998–1006. http://dx.doi.org/10.1115/1.3239847.
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The unsteady effects of shock waves and wakes shed by the nozzle guide vane row on the flow over a downstream turbine rotor have been simulated in a transient cascade tunnel. At conditions representative of engine flow, both wakes and shock waves are shown to cause transient turbulent patches to develop in an otherwise laminar (suction-surface) boundary layer. The simulation technique employed, coupled with very high-frequency heat transfer and pressure measurements, and flow visualization, allowed the transition initiated by isolated wakes and shock waves to be studied in detail. On the profile tested, the comparatively weak shock waves considered do not produce significant effects by direct shock-boundary layer interaction. Instead, the shock initiates a leading edge separation, which subsequently collapses, leaving a turbulent patch that is convected downstream. Effects of combined wake- and shock wave-passing at high frequency are also reported.
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Filipovic, Nenad, and Milos Kojic. "Computer simulations of blood flow with mass transport through the carotid artery bifurcation." Theoretical and Applied Mechanics 31, no. 1 (2004): 1–33. http://dx.doi.org/10.2298/tam0401001f.
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The current paradigm for clinical diagnostic for the treatment of vascular disease relies exclusively on diagnostic imaging data to define the present state of the patient, empirical data to evaluate the efficacy of prior treatments for similar patients. These techniques are insufficient to predict the outcome of a given treatment for an individual patient. We here propose a new paradigm of predictive medicine where physician could use computational simulation to construct and evaluate a specific geometrical/anatomical model to predict the outcome for an individual patient. For this purpose it is necessary to develop a complex software system which combines user friendly interface, automatic solid modeling, automatic finite mesh generation, computational fluid dynamics and post-processing visualization. The flow dynamics is defined according to the incompressible Navier-Stokes equations for Newtonian and non-Newtonian fluids. Mass transport of oxygen and macromolecules is modeled by the convection diffusion equation and coupled with flow dynamics. The computer simulations are based upon finite element analysis where the new computer methods for coupling oxygen transport and fluid flow are described. The comparison results shows a good agreement between clinical observation for critical zones of flow separation, flow recirculation, low wall shear stresses which may contribute to the development of atherosclerotic diseases.
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Wolfgang, M. J., J. M. Anderson, M. A. Grosenbaugh, D. K. Yue, and M. S. Triantafyllou. "Near-body flow dynamics in swimming fish." Journal of Experimental Biology 202, no. 17 (September 1, 1999): 2303–27. http://dx.doi.org/10.1242/jeb.202.17.2303.
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We consider the motions and associated flow patterns of a swimming giant danio (Danio malabaricus). Experimental flow-visualization techniques have been employed to obtain the unsteady two-dimensional velocity fields around the straight-line swimming motions and a 60 degrees turn of the fish in the centerline plane of the fish depth. A three-dimensional numerical method is also employed to predict the total velocity field through simulation. Comparison of the experimental and numerical velocity and vorticity fields shows good agreement. The fish morphology, with its narrow peduncle region, allows for smooth flow into the articulated tail, which is able to sustain a large load for thrust generation. Streamlines of the flow detail complex processes that enhance the efficiency of flow actuation by the tail. The fish benefits from smooth near-body flow patterns and the generation of controlled body-bound vorticity, which is propagated towards the tail, shed prior to the peduncle region and then manipulated by the caudal fin to form large-scale vortical structures with minimum wasted energy. This manipulation of body-generated vorticity and its interaction with the vorticity generated by the oscillating caudal fin are fundamental to the propulsion and maneuvering capabilities of fish.
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Ghim, Mean, Paola Alpresa, Sung-Wook Yang, Sietse T. Braakman, Stephen G. Gray, Spencer J. Sherwin, Maarten van Reeuwijk, and Peter D. Weinberg. "Visualization of three pathways for macromolecule transport across cultured endothelium and their modification by flow." American Journal of Physiology-Heart and Circulatory Physiology 313, no. 5 (November 1, 2017): H959—H973. http://dx.doi.org/10.1152/ajpheart.00218.2017.
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Transport of macromolecules across vascular endothelium and its modification by fluid mechanical forces are important for normal tissue function and in the development of atherosclerosis. However, the routes by which macromolecules cross endothelium, the hemodynamic stresses that maintain endothelial physiology or trigger disease, and the dependence of transendothelial transport on hemodynamic stresses are controversial. We visualized pathways for macromolecule transport and determined the effect on these pathways of different types of flow. Endothelial monolayers were cultured under static conditions or on an orbital shaker producing different flow profiles in different parts of the wells. Fluorescent tracers that bound to the substrate after crossing the endothelium were used to identify transport pathways. Maps of tracer distribution were compared with numerical simulations of flow to determine effects of different shear stress metrics on permeability. Albumin-sized tracers dominantly crossed the cultured endothelium via junctions between neighboring cells, high-density lipoprotein-sized tracers crossed at tricellular junctions, and low-density lipoprotein-sized tracers crossed through cells. Cells aligned close to the angle that minimized shear stresses across their long axis. The rate of paracellular transport under flow correlated with the magnitude of these minimized transverse stresses, whereas transport across cells was uniformly reduced by all types of flow. These results contradict the long-standing two-pore theory of solute transport across microvessel walls and the consensus view that endothelial cells align with the mean shear vector. They suggest that endothelial cells minimize transverse shear, supporting its postulated proatherogenic role. Preliminary data show that similar tracer techniques are practicable in vivo. NEW & NOTEWORTHY Solutes of increasing size crossed cultured endothelium through intercellular junctions, through tricellular junctions, or transcellularly. Cells aligned to minimize the shear stress acting across their long axis. Paracellular transport correlated with the level of this minimized shear, but transcellular transport was reduced uniformly by flow regardless of the shear profile.
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Flórez-Ruiz, Juan Fernando, Jorge Guillermo Díaz-Rodríguez, Alexander Ramírez-Dueñes, and Félix Antonio Pérez-Rondón. "Design, simulation and construction of a pellets transportation laboratory." ITECKNE 16, no. 2 (December 16, 2019): 7–17. http://dx.doi.org/10.15332/iteckne.v16i2.2352.
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The article presents how three scaled down industrial machinery models were designed and built as an educational tool to present the transport of particulate material. The literature review showed calculation models for equipment at industrial level, not for laboratory level. There were chosen the most representative means of commercial transport for particulate materials: a conveyor screw, a conveyor belt and a bucket elevator. These three machines were calculated and built in polycarbonate to allow visualization of their internal functioning. The three devices are controlled by a programmable logic controller (PLC) and connected to each other by a SCADA network. The equipment is modular so as not to alter the order of operation, being able to obtain different work sequences. In addition, a man-machine graphic interface (HMI) was developed to supervise and to control the designed equipment. The results of particulate material mass flow obtained are approximately coincident with those estimated, validating the use of calculation models for much lower levels of work. Finally, it is emphasized that the system obtained is an environment for students to implement control techniques using the sensors and motors used in the designs.
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Park, Sebeom, Shokhrukh Bokijonov, and Yosoon Choi. "Review of Microsoft HoloLens Applications over the Past Five Years." Applied Sciences 11, no. 16 (August 6, 2021): 7259. http://dx.doi.org/10.3390/app11167259.
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Since Microsoft HoloLens first appeared in 2016, HoloLens has been used in various industries, over the past five years. This study aims to review academic papers on the applications of HoloLens in several industries. A review was performed to summarize the results of 44 papers (dated between January 2016 and December 2020) and to outline the research trends of applying HoloLens to different industries. This study determined that HoloLens is employed in medical and surgical aids and systems, medical education and simulation, industrial engineering, architecture, civil engineering and other engineering fields. The findings of this study contribute towards classifying the current uses of HoloLens in various industries and identifying the types of visualization techniques and functions.
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Yilmaz, Erdal, and Shahrouz Aliabadi. "Surface conformed linear mesh and data subdivision technique for large-scale flow simulation and visualization in Variable Intensity Computational Environment." Computers & Fluids 80 (July 2013): 388–402. http://dx.doi.org/10.1016/j.compfluid.2012.01.017.
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PEREIRA, J. C. F., and J. M. M. SOUSA. "Confined vortex breakdown generated by a rotating cone." Journal of Fluid Mechanics 385 (April 25, 1999): 287–323. http://dx.doi.org/10.1017/s002211209900436x.
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Confined vortex breakdown generated by a rotating cone within a closed cylindrical container has been studied both by numerical simulation and by experimental techniques. A comprehensive investigation of the various flow regimes has been carried out by flow visualization. From laser–Doppler measurements of the entire flow field (three velocity components) detailed maps of the time-averaged flow structures for single and double breakdown have been constructed. Three-dimensional time-dependent simulations of steady and unsteady breakdown have been performed. Steady numerical and experimental flow fields obtained at Reynolds number 2200 for a gap ratio of 2 show notable agreement. At critical Reynolds numbers of approximately 3095, for a gap ratio of 2, and 2435, for a gap ratio of 3, the flow was observed becoming unsteady. The periodic behaviour exhibited by the unsteady flow suggested the occurrence of a supercritical Hopf bifurcation. This conjecture was confirmed by the evolution of the oscillation amplitude as a function of criticality, measured for a gap ratio of 3. The dynamical behaviour of unsteady vortex breakdown structures is depicted by numerical simulation of two distinct oscillatory regimes, at Reynolds numbers 2700 and 3100. A thorough analysis of the numerical results has shown that whereas the former regime is characterized by the steady oscillation of closely axisymmetric breakdowns, the latter displays precession of breakdown structures about the central axis. Additionally, it was observed that the mode bringing about the Hopf bifurcation is non-axisymmetric, with azimuthal periodicity of π/2 radians. From examination of measured velocity power spectra at higher Reynolds numbers, a transition scenario was also educed. In the present case, the Ruelle–Takens–Newhouse theorem has been shown to apply.
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Cinar, Yildiray, Kristian Jessen, Roman Berenblyum, Ruben Juanes, and Franklin M. Orr. "An Experimental and Numerical Investigation of Crossflow Effects in Two-Phase Displacements." SPE Journal 11, no. 02 (June 1, 2006): 216–26. http://dx.doi.org/10.2118/90568-pa.
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Summary In this paper, we present flow visualization experiments and numerical simulations that demonstrate the combined effects of viscous and capillary forces and gravity segregation on crossflow that occurs in two-phase displacements in layered porous media. We report results of a series of immiscible flooding experiments in 2D, two-layered glass bead models. Favorable mobility-ratio imbibition and unfavorable mobility-ratio drainage experiments were performed. We used pre-equilibrated immiscible phases from a ternary isooctane/isopropanol/water system, which allowed control of the interfacial tension (IFT) by varying the isopropanol concentration. Experiments were performed for a wide range of capillary and gravity numbers. The experimental results illustrate the transitions from flow dominated by capillary pressure at high IFT to flow dominated by gravity and viscous forces at low IFT. The experiments also illustrate the complex interplay of capillary, gravity, and viscous forces that controls crossflow. The experimental results confirm that the transition ranges of scaling groups suggested by Zhou et al. (1994) are appropriate/valid. We report also results of simulations of the displacement experiments by two different numerical techniques: finite-difference and streamline methods. The numerical simulation results agree well with experimental observations when gravity and viscous forces were most important. For capillary-dominated flows, the simulation results are in reasonable agreement with experimental observations. Introduction Streamline methods are very efficient numerical techniques for field-scale reservoir simulation, but they are not without limitations. They treat flow along each streamline as independent of adjacent streamlines and therefore do not typically represent crossflow in the simulations. If users of streamline methods are to interpret simulation results reliably, they will need to assess whether any of the mechanisms not modeled in the simulations ar. important enough to limit the accuracy of the simulations appreciably. Transfer of fluid in the direction transverse to streamlines can result from diffusion and dispersion, crossflow caused by viscous and capillary forces, and gravity segregation. The scaling of diffusion and dispersion has been investigated in a number of previous studies. If the injected gas is miscible or partially miscible with the oil, diffusion and dispersion mechanisms may play a significant role in the displacement (Mohanty and Johnson 1993; Fayers and Lee 1994; Tchelepi 1994; Jiang and Butler 1994; Burger and Mohanty 1997). In particular, Burger and Mohanty (1997) showed that diffusion through the oil phase can limit mass transfer from oil residing in low-permeability regions. Similar arguments can also apply to other mechanisms of crossflow: viscous and capillary crossflow as well as gravity segregation (Fayers and Lee 1994.Burger and Mohanty 1997; Zapata and Lake 1981; Zhou et al. 1994).
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Rani, Hari Ponnamma, Narayana Vekamulla, Yadagiri Rameshwar, and Sergey Vladimirovich Starchenko. "ASPECT RATIO EFFECTS ON BOTTOM HEATED 2D CAVITY USING ENERGY STREAMLINES AND FIELD SYNERGY PRINCIPLE." Latin American Applied Research - An international journal 50, no. 1 (October 9, 2019): 41–46. http://dx.doi.org/10.52292/j.laar.2020.164.
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In the present work free convective air flow in the two-dimensional cavity with three different aspect ratios (AR) are investigated using direct numerical simulation. The bottom wall is assumed to be kept at a uniform higher temperature than that of the top wall and the other two vertical walls are assumed to be thermally insulated. The computations are conducted for Rayleigh number (Ra) values from 103 to 106. Convective schemes are compared and Self Filtered Central Differencing Scheme is used to discretize convective term. Parallel computing MPI code is adapted to run the simulations. An attempt has been made to gather the visualization techniques such as streamlines, isotherms, energy streamlines and field synergy principle to analyse the flow behaviour inside the cavity. When Ra is small, the vertical energy streamlines are observed in the cavity. As Ra further increased, the free energy streamlines observed at the boundary and the trapped energy streamlines at the centre in the horizontal direction. For a fixed Ra, and increasing AR, the average synergy angle increases. This indicates synergy or the coordination between velocity magnitude and temperature field gets decreased and leads to the growth of heat transfer rate. The field synergy principle implies by enhancing the synergy between the velocity vector and temperature gradient.
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Heilala, J., J. Montonen, and O. Väätäinen. "Life cycle and unit-cost analysis for modular reconfigurable flexible light assembly systems." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 222, no. 10 (October 1, 2008): 1289–99. http://dx.doi.org/10.1243/09544054jem1034.
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The article presents a decision support methodology for the selection of a modular reconfigurable assembly system using three-dimensional visualization, component-based simulation, efficiency, and economic analysis methodology. During the design and selection of an assembly system, measurement schemes should be established for determining and understanding design effectiveness. Measurements can be classed into two categories: cost and performance. Understanding assembly production costs is the first step towards increasing profits. The authors have developed an analysis method that integrates factory simulation, overall equipment efficiency (OEE), and economic analysis methods. Cost calculation includes life cycle cost (LCC), cost of ownership (COO), commonly used investment evaluation methods, discounted cash flow techniques, net present value (NPV), and internal rate of return (IRR). The idea is to use these integrated analysis methods in the selection and development of a light assembly system. The development is based on selected industrial standards and the authors’ own experience in assembly system design and simulation. The developed TCO (total cost of ownership) methodology is useful in system supplier and end-user communication; ideally, it is used in the assembly system sales process, it helps in trade-off analysis of the system concepts, and it improves system specification.
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Jujuly, M. M., Mohammad Azizur Rahman, Aaron Maynard, and Matthew Adey. "Hydrate-Induced Vibration in an Offshore Pipeline." SPE Journal 25, no. 02 (December 31, 2019): 732–43. http://dx.doi.org/10.2118/187378-pa.
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Summary Gas-hydrate plugging poses an operational challenge to offshore petroleum production and transportation. In this study, a computational-fluid-dynamics (CFD) model that uses ANSYS Fluent (ANSYS 2019) multiphase-flow-modeling techniques to simulate and analyze the effect of gas-hydrate flow in pipelines is proposed. For this purpose, the study attempted to integrate the ANSYS Fluent model with an existing commercial subsea-pipeline-visualization tool. To validate the simulation results, two case studies were conducted. The first study was about a pipeline whose dimensions are based on the specifications in existing literature (Balakin et al. 2010a). The second study was about a pipeline with more-complex geometry (M-shaped jumper with six elbows). The Eulerian/Eulerian method was used to model the multiphase hydrate flow. The population-balance method (PBM) was then used to model hydrate agglomeration and its breakup mechanism in the flow. A parametric study of the stresses in the pipelines resulting from flow-induced vibration (FIV) was conducted to identify the regions that underwent the maximum stresses and deformations under various flow conditions. The tool can be used in the petroleum industry to identify the operational hazards in offshore structures and to take necessary safety measures to avoid any potential catastrophic events.
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Liu, Richeng, Yujing Jiang, Hongwen Jing, and Liyuan Yu. "Nonlinear Flow Characteristics of a System of Two Intersecting Fractures with Different Apertures." Processes 6, no. 7 (July 20, 2018): 94. http://dx.doi.org/10.3390/pr6070094.
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The nonlinear flow regimes of a crossed fracture model consisting of two fractures have been investigated, in which the influences of hydraulic gradient, surface roughness, intersecting angle, and scale effect have been taken into account. However, in these attempts, the aperture of the two crossed fractures is the same and effects of aperture ratio have not been considered. This study aims to extend their works, characterizing nonlinear flow through a system of two intersecting fractures with different apertures. First, three experiment models with two fractures having different apertures were established and flow tests were carried out. Then, numerical simulations by solving the Navier-Stokes equations were performed and the results compared with the experiment results. Finally, the effects of fracture aperture on the critical pressure difference and the ratio of hydraulic aperture to mechanical aperture were systematically analyzed. The results show that the numerical simulation results agree well with those of the fluid flow tests, which indicates that the visualization techniques and the numerical simulation code are reliable. With the increment of flow rate, the pressure difference increases first linearly and then nonlinearly, which can be best fitted using Forchheimer’s law. The two coefficients in Forchheimer’s law decrease with the increasing number of outlets. When increasing fracture aperture from 3 mm to 5 mm, the critical pressure difference increases significantly. However, when continuously increasing fracture aperture from 5 mm to 7 mm, the critical pressure difference changes are negligibly small. The ratio of hydraulic aperture to mechanical aperture decreases more significantly for a fracture that has a larger aperture. Increasing fracture aperture from 5 mm to 7 mm, that has a negligibly small effect on the critical pressure difference will however significantly influence the ratio of hydraulic aperture to mechanical aperture.
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Zheng, Yan, Akira Rinoshika, and Shun Fujimoto. "Three-dimensional wavelet analysis on turbulent structure of dune wake flow." International Journal of Wavelets, Multiresolution and Information Processing 13, no. 06 (November 2015): 1550045. http://dx.doi.org/10.1142/s0219691315500459.
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The three-dimensional (3D) turbulent structure was simulated by large eddy simulation (LES), and then the numerical result was validated by PIV experiment. In order to give a detailed description of dune wake flow, the instantaneous velocity, vorticity, and pressure were decomposed into the large-, intermediate- and relatively small-scale components by 3D wavelet multi-resolution technique. To get a further understanding of coherent structure, the decomposed wavelet components were employed to calculate Q-criterion. It was found that the rollers and horse-shoe structures in the separation bubble were mainly contributed from large-scale structures and it made the most significance to the vorticity concentration. The observations of intermediate-scale horse-shoe structures indicated that the coherent structure was the combined effect of large- and intermediate-scale structures. Besides, from the visualization of 3D streamlines and pressure iso-surfaces, the separation bubble and pressure distribution are found to be dominated by large-scale structure.
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Wu, Zhenlong, Yihua Cao, and M. Ismail. "Numerical Simulation of Airfoil Aerodynamic Penalties and Mechanisms in Heavy Rain." International Journal of Aerospace Engineering 2013 (2013): 1–13. http://dx.doi.org/10.1155/2013/590924.
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Numerical simulations that are conducted on a transport-type airfoil, NACA 64-210, at a Reynolds number of2.6×106and LWC of 25 g/m3explore the aerodynamic penalties and mechanisms that affect airfoil performance in heavy rain conditions. Our simulation results agree well with the experimental data and show significant aerodynamic penalties for the airfoil in heavy rain. The maximum percentage decrease inCLis reached by 13.2% and the maximum percentage increase inCDby 47.6%. Performance degradation in heavy rain at low angles of attack is emulated by an originally creative boundary-layer-tripped technique near the leading edge. Numerical flow visualization technique is used to show premature boundary-layer separation at high angles of attack and the particulate trajectories at various angles of attack. A mathematic model is established to qualitatively study the water film effect on the airfoil geometric changes. All above efforts indicate that two primary mechanisms are accountable for the airfoil aerodynamic penalties. One is to cause premature boundary-layer transition at low AOA and separation at high AOA. The other occurs at times scales consistent with the water film layer, which is thought to alter the airfoil geometry and increase the mass effectively.
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Eloot, S., Y. D'asseler, P. De Bondt, and P. Verdonck. "Combining SPECT Medical Imaging and Computational Fluid Dynamics for Analyzing Blood and Dialysate Flow in Hemodialyzers." International Journal of Artificial Organs 28, no. 7 (July 2005): 739–49. http://dx.doi.org/10.1177/039139880502800713.
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For a better insight in dialyzer efficiency with respect to local mass transport in a low flux dialyzer (Fresenius F6HPS), blood and dialysate flow distributions were visualized with computational fluid dynamic (CFD) simulations, which were validated with single photon emission computed tomography (SPECT) imaging. To visualize blood-side flow while avoiding transport through the fiber membrane, a bolus of 99m-Technetium labeled MAA (Macro Aggregated Albumin) was injected in the flow using an electronic valve. Water was used to simulate blood, but flow rate was adjusted according to laws of dynamic similarity to account for the viscosity difference (factor 2.75). For the visualization of dialysate flow, a bolus of 99m-Technetium labeled DMSA (Dimercaptosuccinic Acid) was injected, while pressurized air in the blood compartment avoided transmembrane flow. For each test series, 3D acquisitions were made on a two respectively three-headed SPECT camera. By evaluating the images at different time steps, dynamic 3D intensity plots were obtained, which were further used to derive local flow velocities. Additionally, three-dimensional CFD models were developed for simulating the overall blood and dialysate flow, respectively. In both models, the whole fiber compartment was defined as a porous medium with overall axial and radial permeability derived theoretically and from in vitro tests. With the imaging as well as with the computational technique, a homogeneous blood flow distribution was found, while vortices and fluid stagnation were observed in the dialyzer inlet manifold. The non-homogeneous dialysate distribution, as found with SPECT imaging, implies the occurrence of non-efficient sites with respect to mass transfer. The discrepancy between the dialysate results of both techniques indicated that the assumption of a constant fiber bundle permeability in the CFD model was too optimistic. In conclusion, medical imaging techniques like SPECT are very helpful to validate CFD models, which can be further applied for dialyzer design and optimization.