Tesi: "Fluid dynamics – Data processing"

1

McBean, Ivan William 1974. "Simulation of 3-dimensional aeroelastic effects in turbomachinery cascades". Monash University, Dept. of Mechanical Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/7690.

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2

Weed, Richard Allen. "Computational strategies for three-dimensional flow simulations on distributed computing systems". Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/12154.

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3

黎浩然 e Ho-yin Albert Lai. "Artificial intelligence based thermal comfort control with CFD modelling". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B3122278X.

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4

Mortensen, Clifton H. "A Computational Fluid Dynamics Feature Extraction Method Using Subjective Logic". BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2208.

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Computational fluid dynamics simulations are advancing to correctly simulate highly complex fluid flow problems that can require weeks of computation on expensive high performance clusters. These simulations can generate terabytes of data and pose a severe challenge to a researcher analyzing the data. Presented in this document is a general method to extract computational fluid dynamics flow features concurrent with a simulation and as a post-processing step to drastically reduce researcher post-processing time. This general method uses software agents governed by subjective logic to make decisions about extracted features in converging and converged data sets. The software agents are designed to work inside the Concurrent Agent-enabled Feature Extraction concept and operate efficiently on massively parallel high performance computing clusters. Also presented is a specific application of the general feature extraction method to vortex core lines. Each agent's belief tuple is quantified using a pre-defined set of information. The information and functions necessary to set each component in each agent's belief tuple is given along with an explanation of the methods for setting the components. A simulation of a blunt fin is run showing convergence of the horseshoe vortex core to its final spatial location at 60% of the converged solution. Agents correctly select between two vortex core extraction algorithms and correctly identify the expected probabilities of vortex cores as the solution converges. A simulation of a delta wing is run showing coherently extracted primary vortex cores as early as 16% of the converged solution. Agents select primary vortex cores extracted by the Sujudi-Haimes algorithm as the most probable primary cores. These simulations show concurrent feature extraction is possible and that intelligent agents following the general feature extraction method are able to make appropriate decisions about converging and converged features based on pre-defined information.

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5

Fahey, Mark, e n/a. "Assessment of the suitability of CFD for product design by analysing complex flows around a domestic oven". University of Otago. Department of Design Studies, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070417.111809.

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Competitive global markets are increasing the commercial pressure on manufacturing companies to develop better products in less time. To meet these demands, the appliance manufacturer, Fisher & Paykel, has considered the use of computer simulation of fluid flows to assist in product design. This technology, known as Computational Fluid Dynamics (CFD), has the potential to provide rewarding insight into the behaviour of designs involving fluids. However, the investment in CFD is not without risk. This thesis investigates the use of CFD in oven design expressly to evaluate the numerical accuracy and suitability of CFD in the context of oven product development. CFD was applied to four cases related to oven design, along with detailed experimental investigations, and resulted in a number of relevant findings. In a study of an impinging jet, the SST turbulence model was found to produce better results than the k-ε turbulence model. Measurements indicated that the flow was unsteady, but CFD struggled to reproduce this behaviour. The synergy between experimental and numerical techniques was highlighted in the simulation of a two-pane oven door, and resulted in temperatures on outer surface of the door predicted by CFD to within 2% of measured values. In the third study, a CFD simulation of a tangential fan failed to deliver acceptable steady-state results, however a transient simulation showed promise. The final case examined the flows through the door and cooling circuit of the Titan oven. Velocities predicted by CFD compared well against measurements in some regions, such as the potential core of the jet at the outlet vent, but other regions, such as entrained air, were poor. Temperatures were predicted to within an average of 2% of measured values. It is found that limited accuracy does not necessarily prevent CFD from delivering engineering value to the product development process. The engineering value delivered by CFD is instead more likely to be limited by the abilities of the user. Incompatibilities between CFD and the product development process can reduce the potential value of CFD but the effects can be minimised by appropriate management action. The benefits of CFD are therefore found to be sufficient to merit its use in the product development process, provided its integration into the organisation is managed effectively and the tool is used with discernment. Recommendations for achieving this are provided.

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6

Aliaga, Rivera Cristhian Neil. "An unsteady multiphase approach to in-flight icing /". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112552.

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Ice accretion is a purely unsteady phenomenon that is presently approximated by most icing codes using quasi-steady modeling. The accuracy of ice prediction is thus directly related to the arbitrarily prescribed time span during which the impact of ice growth on both flow and droplets is neglected. The objective of this work is to remove this limitation by implementing a cost-effective unsteady approach. This is done by fully coupling, in time, a diphasic flow (interacting air and droplet particles) with the ice accretion model. The two-phase flow is solved using the Navier-Stokes and Eulerian droplet equations with dual-time stepping in order to improve computational time. The ice shape is either obtained from the conservation of mass and energy within a thin film layer for glaze and mixed icing conditions, or from a mass balance between water droplets impingement and mass flux of ice for rime icing conditions. The iced surface being constantly displaced in time, Arbitrary Lagrangian-Eulerian terms are added to the governing equations to account for mesh movement. Moreover, surface smoothing techniques are developed to prevent degradation of the iced-surface geometric discretization. For rime ice, the numerical results clearly show that the new full unsteady modeling improves the accuracy of ice prediction, compared to the quasi-steady approach, while in addition ensuring time span independence. The applicability of the unsteady icing model for predicting glaze ice accretion is also demonstrated by coupling the diphasic model to the Shallow Water Icing Model. A more rigorous analysis reveals that this model requires the implementation of local surface roughness and that previous quasi-steady validations cannot be carried out using a small number of shots, therefore the need for unsteady simulation.

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7

Nakakita, Kunio. "Toward real-time aero-icing simulation using reduced order models". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99781.

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Even though the power of supercomputers has increased extraordinarily, there is still an insatiable need for more advanced multi-disciplinary CFD simulations in the aircraft analysis and design fields. A particular current interest is in the realistic three-dimensional fully viscous turbulent flow simulation of the highly non-linear aspects of aero-icing. This highly complex simulation is still computationally too demanding in industry, especially when several runs, such as parametric studies, are needed. In order to make such compute-intensive simulations more affordable, this work presents a reduced order modeling approach, based on the "Proper Orthogonal Decomposition", (POD), method to predict a wider swath of flow fields and ice shapes based on a limited number of "snapshots" obtained from complete high-fidelity CFD computations. The procedure of the POD approach is to first decompose the fields into modes, using a limited number of full-calculations snapshots, and then to reconstruct the field and/or ice shapes using those decomposed modes for other conditions, leading to reduced order calculations. The use of the POD technique drastically reduces the computational cost and can provide a more complete map of the performance degradation of an iced aircraft over a wide range of flight and weather conditions.

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8

Somani, Ankit. "Advanced thermal management strategies for energy-efficient data centers". Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/26527.

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Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Joshi, Yogendra; Committee Member: ghiaasiaan, mostafa; Committee Member: Schwan, Karsten. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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9

Sjölund, Johannes. "Real-time Thermal Flow Predictions for Data Centers : Using the Lattice Boltzmann Method on Graphics Processing Units for Predicting Thermal Flow in Data Centers". Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70530.

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The purpose of this master thesis is to investigate the usage of the Lattice Boltzmann Method (LBM) of Computational Fluid Dynamics (CFD) for real-time prediction of indoor air flows inside a data center module. Thermal prediction is useful in data centers for evaluating the placement of heat-generating equipment and air conditioning. To perform the simulation a program called RAFSINE was used, written by Nicholas Delbosc at the University of Leeds, which implemented LBM on Graphics Processing Units (GPUs) using NVIDIA CUDA. The program used the LBM model called Bhatnagar-Gross-Krook (BGK) on a 3D lattice and had the capability of executing thermal simulations in real-time or faster than real-time. This fast rate of execution means a future application for this simulation could be as a predictive input for automated air conditioning control systems, or for fast generation of training data sets for automatic fault detection systems using machine learning. In order to use the LBM CFD program even from hardware not equipped with NVIDIA GPUs it was deployed on a remote networked server accessed through Virtual Network Computing (VNC). Since RAFSINE featured interactive OpenGL based 3D visualization of thermal evolution, accessing it through VNC required use of the VirtualGL toolkit which allowed fast streaming of visualization data over the network. A simulation model was developed describing the geometry, temperatures and air flows of an experimental data center module at RISE SICS North in Luleå, Sweden, based on measurements and equipment specifications. It was then validated by comparing it with temperatures recorded from sensors mounted in the data center. The thermal prediction was found to be accurate on a room-level within ±1° C when measured as the average temperature of the air returning to the cooling units, with a maximum error of ±2° C on an individual basis. Accuracy at the front of the server racks varied depending on the height above the floor, with the lowest points having an average accuracy of ±1° C, while the middle and topmost points had an accuracy of ±2° C and ±4° C respectively. While the model had a higher error rate than the ±0.5° C accuracy of the experimental measurements, further improvements could allow it to be used as a testing ground for air conditioning control or automatic fault detection systems.

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10

Nelson, Graham Martin. "Development of an Experimentally-Validated Compact Model of a Server Rack". Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19726.

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A simplified computational fluid dynamics and heat transfer (CFD-HT) model of an electronics enclosure was developed. The compact model was based on a server simulator, which dissipates a variable amount of heat at an adjustable air flow rate. Even though a server simulator does not accurately represent the geometry of an actual electronics enclosure, the modeling of such a unit deals with many of the same issues as the modeling of actual enclosures. Even at the server simulator level, a disparity in length scales prevents detailed modeling of intricate components most notably grilles, fins, and fans. Therefore, a compact model for each of these components was developed. Fan performance curves were determined experimentally for varying fan rotational speeds. In addition, component pressure drop characteristics were found experimentally for grilles and fin banks, and these empirical relationships were applied to the model as well. To determine the validity of the simplifications employed in the model, experimental outlet temperature and velocity measurements were taken to compare to those provided by the CFD-HT simulations.

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11

Lundqvist, Viktor. "A smoothed particle hydrodynamic simulation utilizing the parallel processing capabilites of the GPUs". Thesis, Linköping University, Department of Science and Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-21761.

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Simulating fluid behavior has proven to be a demanding challenge which requires complex computational models and highly efficient data structures. Smoothed Particle Hydrodynamics (SPH) is a particle based computational model used to simulate fluid behavior that has been found capable of producing convincing results. However, the SPH algorithm is computational heavy which makes it cumbersome to work with.

This master thesis describes how the SPH algorithm can be accelerated by utilizing the GPU’s computational resources. It describes a model for how to distribute the work load on the GPU and presents a suitable data structure. In addition, it proposes a method to represent and handle moving objects in the fluids surroundings. Finally, the performance gain due to the GPU is evaluated by comparing processing times with an identical implementation running solely on the CPU.

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12

Horko, Michael. "CFD optimisation of an oscillating water column wave energy converter". University of Western Australia. School of Mechanical Engineering, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0089.

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Although oscillating water column type wave energy devices are nearing the stage of commercial exploitation, there is still much to be learnt about many facets of their hydrodynamic performance. This research uses the commercially available FLUENT computational fluid dynamics flow solver to model a complete OWC system in a two dimensional numerical wave tank. A key feature of the numerical modelling is the focus on the influence of the front wall geometry and in particular the effect of the front wall aperture shape on the hydrodynamic conversion efficiency. In order to validate the numerical modelling, a 1:12.5 scale experimental model has been tested in a wave tank under regular wave conditions. The effects of the front lip shape on the hydrodynamic efficiency are investigated both numerically and experimentally and the results compared. The results obtained show that with careful consideration of key modelling parameters as well as ensuring sufficient data resolution, there is good agreement between the two methods. The results of the testing have also illustrated that simple changes to the front wall aperture shape can provide marked improvements in the efficiency of energy capture for OWC type devices.

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13

Shrivastava, Saurabh K. "Cooling analysis of data centers CFD modeling and real-time calculators /". Diss., Online access via UMI:, 2008.

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Abstract (sommario):

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008.
Includes bibliographical references.

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14

Johnson, Kevin Robert. "In Vivo Coronary Wall Shear Stress Determination Using CT, MRI, and Computational Fluid Dynamics". Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14482.

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Wall shear stress (WSS) has long been identified as a factor in the development of atherosclerotic lesions. Autopsy studies have revealed a strong tendency for lesion development at arterial branch sites and along the inner walls of curvature areas that, in theory, should experience low WSS. Calculations of coronary artery WSS have typically been based upon average models of coronary artery geometry with average flow conditions and then compared to average lesion distributions. With all the averaging involved, a more detailed knowledge of the correlation between WSS and atherosclerotic lesion development might be obscured. Recent advancements in hemodynamic modeling now enable the calculation of WSS in individual subjects. An image-based approach for patient-specific calculation of in vivo WSS using computational fluid dynamics (CFD) would allow a more direct study of this correlation. New state-of-the-art technologies in multi-detector computed tomography (CT) and 3.0 Tesla magnetic resonance imaging (MRI) offer potential improvements for the measurement of coronary artery geometry and blood flow. The overall objective of this research was to evaluate the quantitative accuracy of multi-detector CT and 3.0 Tesla MRI and incorporate those imaging modalities into a patient-specific CFD model of coronary artery WSS. Using a series of vessel motion phantoms, it has been shown that 64-detector CT can provide accurate measurements of coronary artery geometry for heart rates below 70 beats per minute. A flow phantom was used to validate the use of navigator-echo gated, phase contrast MRI at 3.0 Tesla to measure velocity of coronary blood flow. Patient-specific, time-resolved CFD models of coronary WSS were created for two subjects. Furthermore, it was determined that population-average velocity curves or steady state velocities can predict locations of high or low WSS with high degrees of accuracy compared to the use of patient-specific blood flow velocity measurements as CFD boundary conditions. This work is significant because it constitutes the first technique to non-invasively calculate in vivo coronary artery WSS using image-based, patient-specific modeling.

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15

Blanc, Trevor Jon. "Analysis and Compression of Large CFD Data Sets Using Proper Orthogonal Decomposition". BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5303.

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Efficient analysis and storage of data is an integral but often challenging task when working with computation fluid dynamics mainly due to the amount of data it can output. Methods centered around the proper orthogonal decomposition were used to analyze, compress, and model various simulation cases. Two different high-fidelity, time-accurate turbomachinery simulations were investigated to show various applications of the analysis techniques. The first turbomachinery example was used to illustrate the extraction of turbulent coherent structures such as traversing shocks, vortex shedding, and wake variation from deswirler and rotor blade passages. Using only the most dominant modes, flow fields were reconstructed and analyzed for error. The reconstructions reproduced the general dynamics within the flow well, but failed to fully resolve shock fronts and smaller vortices. By decomposing the domain into smaller, independent pieces, reconstruction error was reduced by up to 63 percent. A new method of data compression that combined an image compression algorithm and the proper orthogonal decomposition was used to store the reconstructions of the flow field, increasing data compression ratios by a factor of 40.The second turbomachinery simulation studied was a three-stage fan with inlet total pressure distortion. Both the snapshot and repeating geometry methods were used to characterize structures of static pressure fluctuation within the blade passages of the third rotor blade row. Modal coefficients filtered by frequencies relating to the inlet distortion pattern were used to produce reconstructions of the pressure field solely dependent on the inlet boundary condition. A hybrid proper orthogonal decomposition method was proposed to limit burdens on computational resources while providing high temporal resolution analysis.Parametric reduced order models were created from large databases of transient and steady conjugate heat transfer and airfoil simulations. Performance of the models were found to depend heavily on the range of the parameters varied as well as the number of simulations used to traverse that range. The heat transfer models gave excellent predictions for temperature profiles in heated solids for ambitious parameter ranges. Model development for the airfoil case showed that accuracy was highly dependent on modal truncation. The flow fields were predicted very well, especially outside the boundary layer region of the flow.

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16

Jawahar, P. "A High-Resolution Procedure For Euler And Navier-Stokes Computations On Unstructured Grids". Thesis, Indian Institute of Science, 2000. https://etd.iisc.ac.in/handle/2005/226.

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A finite-volume procedure, comprising a gradient-reconstruction technique and a multidimensional limiter, has been proposed for upwind algorithms on unstructured grids. The high-resolution strategy, with its inherent dependence on a wide computational stencil, does not suffer from a catastrophic loss of accuracy on a grid with poor connectivity as reported recently is the case with many unstructured-grid limiting procedures. The continuously-differentiable limiter is shown to be effective for strong discontinuities, even on a grid which is composed of highly-distorted triangles, without adversely affecting convergence to steady state. Numerical experiments involving transient computations of two-dimensional scalar convection to steady-state solutions of Euler and Navier-Stokes equations demonstrate the capabilities of the new procedure.

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17

Jawahar, P. "A High-Resolution Procedure For Euler And Navier-Stokes Computations On Unstructured Grids". Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/226.

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Abstract (sommario):

A finite-volume procedure, comprising a gradient-reconstruction technique and a multidimensional limiter, has been proposed for upwind algorithms on unstructured grids. The high-resolution strategy, with its inherent dependence on a wide computational stencil, does not suffer from a catastrophic loss of accuracy on a grid with poor connectivity as reported recently is the case with many unstructured-grid limiting procedures. The continuously-differentiable limiter is shown to be effective for strong discontinuities, even on a grid which is composed of highly-distorted triangles, without adversely affecting convergence to steady state. Numerical experiments involving transient computations of two-dimensional scalar convection to steady-state solutions of Euler and Navier-Stokes equations demonstrate the capabilities of the new procedure.

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18

Hua, Li. "Vector wavelet transforms for the coding of static and time-varying vector fields". Diss., Mississippi State : Mississippi State University, 2003. http://library.msstate.edu/etd/show.asp?etd=etd-05062003-120341.

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19

Suo, Jin. "Investigation of blood flow patterns and hemodynamics in the human ascending aorta and major trunks of right and left coronary arteries using magnetic resonance imaging and computational fluid dynamics". Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-01192005-121529/unrestricted/suo%5Fjin%5F200505%5Fphd.pdf.

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Thesis (Ph. D.)--Biomedical Engineering, Georgia Institute of Technology, 2005.
Giddens, P. Don, Committee Chair ; Vito, P. Raymond, Committee Member ; Taylor, Robert, W., Committee Member ; Oshinski, John, Committee Member ; Bao, Gang, Committee Member. Includes bibliographical references.

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20

Schepke, Claudio. "Distribuição de dados para implementações paralelas do Método de Lattice Boltzmann". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/8810.

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A Dinâmica de Fluidos Computacional é uma importante área de pesquisa no contexto da Computação Científica. Através da modelagem e simulação das propriedades de líquidos e gases é possível obter resultados numéricos para diferentes estruturas e fenômenos físicos cotidianos e de grande importância econômica. A evolução dos sistemas computacionais possibilitou a essa área o surgimento de novas técnicas e abordagens de simulação. Uma das técnicas computacionais atualmente empregadas é o Método de Lattice Boltzmann, um método numérico iterativo para a modelagem e simulação mesoscópica da dinâmica de fluxos de fluidos. Diferentes tipos de sistemas físicos podem ser tratados através dessa técnica, como é o caso de fluxos em meios porosos ou de substâncias imiscíveis. No entanto, por causa da dimensão dos sistemas físicos, é necessário adotar estratégias que permitam a obtenção de resultados precisos ou em tempos computacionais aceitáveis. Assim, paralelizar as operações é a solução mais indicada para aumentar o desempenho do método. Uma maneira eficiente de paralelizar um método numérico é fazer uso de técnicas de distribuição de dados refinadas, como é o caso do particionamento em blocos. Tais abordagens de paralelização foram adotadas neste trabalho em implementações bi- e tridimensionais do Método de Lattice Boltzmann, com o intuito de avaliar o ganho de desempenho oferecido através dessa técnica. Além disso, foram definidos os fatores que influenciam as melhores configurações de particionamento. Os resultados obtidos demonstraram que o particionamento em blocos prove um aumento considerável do desempenho das aplicações paralelas, especialmente para a versão tridimensional do método. Para algumas configurações dos estudos de caso os tempos de execução diminuíram em até 30% em relação aos tempos obtidos com o particionamento unidimensional. Já as melhores configurações para a distribuição dos dados em blocos foram aquelas em que a disposição dos dados manteve-se mais quadrada ou cúbica em relação a cada uma das dimensões coordenadas.
Computational Fluid Dynamics is an important research area in the Scientific Computing context. Through the modeling and simulation of liquids and gases properties it is possible to get numerical results for different physical structures and daily phenomena that have great economic importance. The evolution of the computational systems made it possible to develop new techniques and approaches of simulation in this area. One of these techniques currently used is the Lattice Boltzmann Method. This method is an iterative numerical strategy for modeling and simulating mesoscopic dynamics of fluid flows. Different types of physical systems can be simulated through this technique, like immiscible substances and flows in porous media. However, since the dimension of the physical systems is usually large, it is necessary to adopt strategies that allow to get accurate results or results in an acceptable computational time. Thus, the parallelization of the operations is the best alternative to increase the performance of the method. An efficient way to parallelize a numerical method is to make use of refined data distribution techniques, like data partitioning in blocks. Such parallelization approach had been adopted in this work for bi- and three-dimensional implementations of the Lattice Boltzmann Method. The objective of the work was to evaluate the performance enhancement offered through the parallelization. Moreover, another objective is to define the elements that influence the best partitioning configurations. The results shown that data partitioning in blocks provide a considerable performance increase for parallel implementations, especially for the three-dimensional version of the method. For some configurations adopted in the case studies, the execution time was reduced of up to 30% in relation to the one-dimensional partitioning strategy. The best configurations for data distribution in blocks were that where the data disposal are more square or cubical shaped in relation to each one of the coordinate dimensions

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Peng, Zhenmin. "Interactive visualization of computational fluid dynamics data". Thesis, Swansea University, 2011. https://cronfa.swan.ac.uk/Record/cronfa42757.

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This thesis describes a literature study and a practical research in the area of flow visualization, with special emphasis on the interactive visualization of Computational Fluid Dynamics (CFD) datasets. Given the four main categories of flow visualization methodology; direct, geometric, texture-based and feature-based flow visualization, the research focus of our thesis is on the direct, geometric and feature-based techniques. And the feature-based flow visualization is highlighted in this thesis. After we present an overview of the state-of-the-art of the recent developments in the flow visualization in higher spatial dimensions (2.5D, 3D and 4D), we propose a fast, simple, and interactive glyph placement algorithm for investigating and visualizing boundary flow data based on unstructured, adaptive resolution boundary meshes from CFD dataset. Afterward, we propose a novel, automatic mesh-driven vector field clustering algorithm which couples the properties of the vector field and resolution of underlying mesh into a unified distance measure for producing high-level, intuitive and suggestive visualization of large, unstructured, adaptive resolution boundary CFD meshes based vector fields. Next we present a novel application with multiple-coordinated views for interactive information-assisted visualization of multidimensional marine turbine CFD data. Information visualization techniques are combined with user interaction to exploit our cognitive ability for intuitive extraction of flow features from CFD datasets. Later, we discuss the design and implementation of each visualization technique used in our interactive flow visualization framework, such as glyphs, streamlines, parallel coordinate plots, etc. In this thesis, we focus on the interactive visualization of the real-world CFD datasets, and present a number of new methods or algorithms to address several related challenges in flow visualization. We strongly believe that the user interaction is a crucial part of an effective data analysis and visualization of large and complex datasets such as CFD datasets we use in this thesis. In order to demonstrate the use of the proposed techniques in this thesis, CFD domain experts reviews are also provided.

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Lundvall, Johan. "Data Assimilation in Fluid Dynamics using Adjoint Optimization". Doctoral thesis, Linköping : Matematiska institutionen, Linköpings universitet, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9684.

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23

Zhang, Wenbing. "A method and program for quantitative description of fracture data and fracture data extrapolation from scanline or wellbore data /". May be available electronically:, 2001. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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24

Lani, Andrea. "An object oriented and high performance platform for aerothermodynamics simulation". Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210428.

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Abstract (sommario):

This thesis presents the author's contribution

to the design and implementation of COOLFluiD,

an object oriented software platform for

the high performance simulation of multi-physics phenomena on unstructured grids. In this context, the final goal has been to provide a reliable tool for handling high speed aerothermodynamic

applications. To this end, we introduce a number of design techniques that have been developed in order to provide the framework with flexibility

and reusability, allowing developers to easily integrate new functionalities such as arbitrary mesh-based data structures, numerical algorithms (space discretizations, time stepping schemes, linear system solvers, ),and physical models.

Furthermore, we describe the parallel algorithms

that we have implemented in order to efficiently

read/write generic computational meshes involving

millions of degrees of freedom and partition them

in a scalable way: benchmarks on HPC clusters with

up to 512 processors show their effective suitability for large scale computing.

Several systems of partial differential equations,

characterizing flows in conditions of thermal and

chemical equilibrium (with fixed and variable elemental fractions)and, particularly, nonequilibrium (multi-temperature models)

have been integrated in the framework.

In order to simulate such flows, we have developed

two state-of-the-art flow solvers:

1- a parallel implicit 2D/3D steady and unsteady cell-centered Finite Volume (FV) solver for arbitrary systems of PDE's on hybrid unstructured meshes;

2- a parallel implicit 2D/3D steady vertex-centered Residual Distribution (RD) solver for arbitrary systems of PDE's on meshes with simplex elements (triangles and tetrahedra).

The FV~code has been extended to handle all

the available physical models, in regimes ranging from incompressible to hypersonic.

As far as the RD code is concerned, the strictly conservative variant of the RD method, denominated CRD, has been applied for the first time in literature to solve high speed viscous flows in thermochemical nonequilibrium, yielding some preliminary outstanding results on a challenging double cone flow simulation.

All the developments have been validated on real-life testcases of current interest in the aerospace community. A quantitative comparison with experimental measurements and/or literature has been performed whenever possible.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

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25

Defforge, Cécile. "Data assimilation for micrometeorological applications with the fluid dynamics model Code_Saturne". Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC1008.

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La qualité de l’air est un enjeu sanitaire et environnemental majeur. Par ailleurs, l'estimation précise des potentiels éoliens est la source d’importantes retombées économiques et environnementales. Pour étudier ces deux sujets, il est nécessaire de reconstituer précisément les champs de vent locaux grâce à des modèles numériques de micrométéorologie. Ces simulations sont extrêmement sensibles aux conditions météorologiques aux limites du domaine d’étude. Jusqu’à présent, les conditions aux limites (CL) étaient estimées à partir de simulations à plus grande échelle, qui fournissent des informations peu adaptées à l’utilisation à l'échelle locale car imprécises, voire incomplètes. Par conséquent, la méconnaissance des CL représente une source majeure d’erreur et d’incertitude dans les études micrométéorologiques.Les sites susceptibles d’accueillir un parc éolien et les environnements bâtis (quartiers urbains ou sites industriels) peuvent être équipés d’instruments de mesures météorologiques ou de concentration de polluants. Les observations qu’ils fournissent constituent une seconde source d’information, jusqu’à ce jour peu exploitée pour les études micrométéorologiques. En effet, les mesures in situ sont perturbées par la géométrie complexe des sites étudiés. Afin d'améliorer la précision des CL et donc des simulations atmosphériques à l'échelle locale, des méthodes d'assimilation de données (AD) adaptées à cette problématique pourraient permettre de mettre à profit les observations disponibles.Jusqu’à présent, les méthodes d’AD ont été principalement développées pour la météorologie à grande échelle et ont donc surtout été utilisées pour corriger les conditions initiales (CI). Afin d'élargir le champ d'application de l’AD à la micrométéorologie, il faut adapter les méthodes existantes pour qu'elles permettent de corriger les CL plutôt que les CI.Deux méthodes d’AD semblent compatibles avec les modèles de mécanique des fluides (CFD) utilisés pour la micrométéorologie en géométrie complexe : l’algorithme de nudging direct et rétrograde (BFN) et le lisseur de Kalman d’ensemble itératif (IEnKS). Nous avons adapté ces deux méthodes d’un point de vue théorique pour inclure les CL dans les variables de contrôle. Les performances des versions adaptées du BFN et de l'IEnKS ont tout d'abord été étudiées avec un modèle simplifié d’écoulement atmosphérique à deux couches en 1D, basé sur les équations de Saint-Venant. Le BFN et l’IEnKS ont ensuite été testés en 2D puis 3D avec le module atmosphérique du modèle open-source de CFD Code_Saturne.Le premier cas d’étude avec Code_Saturne correspond à une application réelle d’estimation de potentiel éolien dans une région montagneuse au relief très accidenté où trois mâts de mesure fournissent des observations de vent. Le second cas correspond à une étude de dispersion de polluants en milieu urbain, basé sur les mesures de vent et de concentration provenant de la campagne « Mock Urban Setting Test » aux États-Unis. Dans ce second cas, la turbulence est également incluse dans les CL. Dans les deux études, une partie des observations est utilisée pour l’assimilation et le reste pour la validation des résultats.Les expériences menées sur le premier cas ont révélé que les modèles de CFD présentent des non-linéarités trop fortes (recirculations derrière les obstacles) pour l’algorithme de BFN, fondé sur une hypothèse de linéarité. L'étude de cette méthode n'a donc pas été poursuivie. En revanche, les deux études ont montré la capacité de l'IEnKS à réduire l'erreur et l'incertitude sur les CL grâce à l'assimilation d'une petite dizaine d'observations, en un nombre raisonnable de calculs. Par suite, les champs de vent simulés sont également plus proches des observations de validation et les intervalles de confiance sont réduits. Finalement, l'IEnKS permet d'estimer le potentiel éolien, dans un cas, et les concentrations en polluant, dans l'autre, avec beaucoup plus de précision et d'exactitude
Air quality is a major health and environmental issue worldwide. Similarly, the accuracy of wind resource assessment triggers significant economic and environmental repercussions. In order to study these two topics, it is necessary to accurately determine local wind fields using numerical models of micrometeorology. Such simulations are extremely sensitive to meteorological conditions at the domain borders. Up to present, the boundary conditions (BC) were estimated based on the results of larger scale simulations, which provide information that is not accurate enough, or even incomplete, for local scale purposes. As a matter of fact, the lack of knowledge about the BC represents a major source of error and uncertainty for micrometeorological studies.The potential sites for wind farm installation as well as built environments (urban areas or industrial sites) can be equipped with instruments measuring meteorological variables or pollutant concentration. The observations provided by these instruments represent a second source of information, insufficiently exploited for micrometeorological studies. Indeed, the in situ measurements are perturbed by the complex geometrical features on sites and might be difficult to exploit. In order to improve the exactitude and the accuracy of the BC, and consequently of the locale-scale atmospheric simulations, data assimilation (DA) methods, suited to this micrometeorological problem, could be applied to take benefit from these available observations.So far, DA methods have been mainly developed for large-scale meteorology and employed to correct the initial conditions (IC). In order to broaden the application scope of DA to micrometeorology, existing DA methods must be adapted to be able to correct the BC instead of IC.Two of the existing DA methods seem compatible with computational fluid dynamics (CFD) models used for micrometeorology over complex geometries: the back and forth nudging (BFN) algorithm and the iterative ensemble Kalman smoother (IEnKS). We have adapted these two methods, from a theoretical perspective, so as to include the BC in the control variables. The performances of the adapted versions of the BFN algorithm and the IEnKS have first been assessed with a simplified, 1D model of atmospheric flow with two layers, based on the shallow-water equations. The BFN algorithm and the IEnKS have then been tested in 2D and 3D with the atmospheric module of the open-source CFD model Code_Saturne.The first study case with Code_Saturne corresponds to a real application of wind resource assessment in a mountainous region with steep topography where three meteorological masts have been installed during a few months and provide in situ wind observations. The second case is a study of pollutant dispersion in an urban area, based on the measurements of wind and pollutant concentration coming from the “Mock Urban Setting Test” field campaign carried out in the USA. In this second case, the turbulence is also included in the BC and thus in the control variables. For both studies, some observations are assimilated and the remaining ones are used to validate the results.The experiences performed for the wind resource assessment study have revealed that the CFD models present too strong nonlinearities (flow recirculation after obstacles) for the BFN algorithm, which is based on a linearity assumption. However, both cases have shown the ability of the IEnKS to reduce the error and the uncertainty of the BC by assimilating a few observations, in operationally affordable conditions. Consequently, the simulated wind fields with Code_Saturne are also closer to the validation observations and the confidence intervals are reduced. Eventually, the IEnKS allows, in one case to estimate the wind potential, and in the other case to build the pollution maps, with much more exactitude and accuracy

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26

Kay, Graham Richard. "A controllable fluid dynamics system for processing pharmaceutical powders in a single vessel". Thesis, University of Bath, 2001. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392014.

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27

Nienhaus, Marc, Bruce Gooch e Jürgen Döllner. "Visualizing movement dynamics in virtual urban environments". Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2009/3306/.

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Dynamics in urban environments encompasses complex processes and phenomena such as related to movement (e.g.,traffic, people) and development (e.g., construction, settlement). This paper presents novel methods for creating human-centric illustrative maps for visualizing the movement dynamics in virtual 3D environments. The methods allow a viewer to gain rapid insight into traffic density and flow. The illustrative maps represent vehicle behavior as light threads. Light threads are a familiar visual metaphor caused by moving light sources producing streaks in a long-exposure photograph. A vehicle’s front and rear lights produce light threads that convey its direction of motion as well as its velocity and acceleration. The accumulation of light threads allows a viewer to quickly perceive traffic flow and density. The light-thread technique is a key element to effective visualization systems for analytic reasoning, exploration, and monitoring of geospatial processes.

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28

Kent, Thomas. "An idealised fluid model of Numerical Weather Prediction : dynamics and data assimilation". Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/17269/.

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The dynamics of the atmosphere span a tremendous range of spatial and temporal scales which presents a great challenge to those who seek to forecast the weather. To aid understanding of and facilitate research into such complex physical systems, `idealised' models can be developed that embody essential characteristics of these systems. This thesis concerns the development of an idealised fluid model of convective-scale Numerical Weather Prediction (NWP) and its use in inexpensive data assimilation (DA) experiments. The model modifies the rotating shallow water equations to include some simplified dynamics of cumulus convection and associated precipitation, extending the model of Wuersch and Craig (2014). Despite the non-trivial modifications to the parent equations, it is shown that the model remains hyperbolic in character and can be integrated accordingly using a discontinuous Galerkin finite element method for nonconservative hyperbolic systems of partial differential equations. Combined with methods to ensure well-balancedness and non-negativity, the resulting numerical solver is novel, efficient, and robust. Classical numerical experiments in shallow water theory, based on the Rossby geostrophic adjustment problem and non-rotating flow over topography, elucidate the model's distinctive dynamics, including the disruption of large-scale balanced flows and other features of convecting and precipitating weather systems. When using such intermediate-complexity models for DA research, it is important to justify their relevance in the context of NWP. A well-tuned observing system and filter configuration is achieved using the ensemble Kalman filter that adequately estimates the forecast error and has an average observational influence similar to NWP. Furthermore, the resulting error-doubling time statistics reflect those of convection-permitting models in a cycled forecast-assimilation system, further demonstrating the model's suitability for conducting DA experiments in the presence of convection and precipitation. In particular, the numerical solver arising from this research provides a useful tool to the community and facilitates other studies in the field of convective-scale DA research.

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29

Robinson, Cordelia. "Image data assimilation with fluid dynamics models : application to 3D flow reconstruction". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S128/document.

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D'une part, les équations de Navier-Stokes permettent de décrire les écoulements fluides, la littérature est riche de méthodes numériques permettant la résolution de celle-ci. D'autre part, nous sommes capables de mesurer de manière non-intrusive différentes caractéristique d'un écoulement (champ de vitesse et pression, etc.). Dans le cadre de cette thèse, nous nous intéressons aux techniques d'assimilation de données qui combinent les modèles numériques avec les observations afin de déterminer une meilleure approximation du système. Cette thèse s'articule autour de l'assimilation de donnée variationnelle (4DVar) qui est plus précise par construction. Nous avons mené une première application sur la reconstruction de la hauteur et vitesse de la surface libre d'un fluide contenu dans un récipient rectangulaire à fond plat. L'écoulement est modélisé par les équations de shallow water et résolues numériquement. Les observations de l'évolution de la hauteur de la surface libre ont été prélevées par un capteur de profondeur (Kinect). Nous avons comparé les résultats de la reconstruction par 4DVar avec plusieurs version de la méthode d'assimilation hybride 4DEnVar. Enfin, nous avons appliqué la technique 4DVar à la reconstruction volumique de l'aval d'un sillage de cylindre à Reynolds 300. L'écoulement turbulent a été simulé par un code DNS parallèle Incompact3D. La reconstruction a été effectué en combinant tout d'abord des observations synthétiques en trois dimension, puis en combinant des observations de plans orthogonales en stéréo PIV
In the one hand, flow dynamics are usually described by the NavierStokes equations and the literature provides a wide range of techniques to solve such equations. On the other hand, we can nowadays measure different characteristics of a flow (velocity, pressure, temperature etc...) with non-intrusive Particle Image Velocimetry techniques. Within this thesis, we take interest in the data assimilation techniques, that combine a dynamics model with measurements to determine a better approximation of the system. This thesis focus on the classic variational assimilation technique (4DVar) which ensures a high accuracy of the solution by construction. We carry out a first application of the 4DVar technique to reconstruct the characteristics (height and velocity field) of a uni directional wave at its free surface. The fluid evolution is simulated by the shallow water equations and solved numerically. We use a simple experimental setup envolving a depth sensor (Kinect sensor) to extract the free surface height. We compared the results of the 4DVar reconstruction with different versions of the hybrid data assimilation technique 4DEnVar. Finally, we apply the 4DVar technique to reconstruct the downstream of a three dimensional cylinder wake at Reynolds 300. The turbulent flow is simulated by the high-performance multi-threading DNS code Incompact3d. This dynamics model is first combined with synthetic three dimensional observations, then with real orthogonal-plane stereo PIV observations to reconstruct the full three dimensional flow

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30

Einstein, Noah. "SmartHub: Manual Wheelchair Data Extraction and Processing Device". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555352793977171.

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31

Pascual, Blanca. "Uncertainty quantification for complex structures : statics and dynamics". Thesis, Swansea University, 2012. https://cronfa.swan.ac.uk/Record/cronfa42987.

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32

Goddard, Kyle Andrew. "Investigation of wind patterns on Marion Island using Computational Fluid Dynamics and measured data". Diss., University of Pretoria, 2021. http://hdl.handle.net/2263/78564.

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There have been countless research investigations taking place on Marion Island (MI), both ecological and geological, which have reached conclusions that must necessarily neglect the impacts of wind on the systems under study. Since only the dominant wind direction of the general atmospheric wind is known from weather and satellite data, not much can be said about local wind conditions at ground level. Therefore, a baseline Computational Fluid Dynamics (CFD) model has been developed for simulating wind patterns over Marion and Prince Edward Islands, a South African territory lying in the subantarctic Indian Ocean. A review of the current state of the art of Computational Wind Engineering (CWE) revealed that large-scale Atmospheric Boundary Layer (ABL) simulations have been successfully performed before with varying degrees of success. With ANSYS Fluent chosen as the numerical solver, the Reynolds-Averaged Navier-Stokes (RANS) equations were set up to simulate a total of 16 wind flow headings approaching MI from each of the cardinal compass directions. The standard k-epsilon turbulence closure scheme with modified constants was used to numerically approximate the atmospheric turbulence. A strategy was devised for generating a reusable mesh system to simulate multiple climatic conditions and wind directions around MI. In conjunction with the computational simulations, a wind measurement campaign was executed to install 17 wind data logging stations at key locations around MI. Raw data output from the stations were cleaned and converted into an easily accessible MySQL database format using the Python scripting language. The Marion Island Recorded Experimental Dataset (MIRED) database contains all wind measurements gathered over the span of two years. The decision was taken to focus on validating only three of the 16 cardinal wind directions against the measured wind data; North-Westerly, Westerly and South-Westerly winds. An initial interrogation of the simulation results showed that island-to-island wake interactions could not be ignored as the turbulent stream from MI could definitely be intercepted by its neighbour under the right conditions, and vice versa. An underestimation of the true strength of the Coriolis effect led to larger wind deflection in the simulations than originally expected, thus resulting in the wind flow at surface levels having an entirely different heading to what was intended. The westerly and south-westerly wind validation cases did not seem too badly affected by the lapse in judgement but the north-westerly case suffered strong losses in accuracy. Significant effort was put into quantifying the error present in the simulations. After a full validation exercise, it was finally resolved to apply a conservative uncertainty factor of 35 % when using these simulations to predict actual wind speed conditions. Similarly, the predicted wind direction can only be trusted within the bounds of a 35 degree prediction uncertainty. Under these circumstances, the baseline CFD model was successfully validated against the measured wind data and can thus be used in further research. In terms of post-processing, all the wind direction simulations have been combined into a single wind velocity map, generated by weighting each of the simulations by the frequency of wind prevalence measured in the corresponding wind sector. A second turbulence intensity combined map has been provided using similar techniques. These maps, as well as the individual wind maps showing all 16 cardinal wind directions, are believed to be helpful to many future biological studies on MI as well as any possible forays into wind energy generation on the island. Despite the encountered deficiencies, this project offers significant value to academia by providing a reliable method of predicting fine-scale wind patterns in a location previously devoid of any accurate data. Furthermore, it has highlighted where future CFD attempts can be improved in order to produce a compelling approximation of the realistic atmospheric phenomena occurring in the Marion Island territory. While error cannot be avoided when modelling such complex systems, it has been well quantified and discussed here so that any further research may make informed judgements in future studies.
Dissertation (MEng)--University of Pretoria, 2021.
South African National Antarctic Programme (SANAP) grant number 110726
National Research Foundation (NRF)
Mechanical and Aeronautical Engineering
MEng
Unrestricted

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33

Asteriadou, Konstantia. "The use of computational fluid dynamics for the microbial assessment of food processing equipment". Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760853.

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34

Arafa, Hicham Abdel-Hamid. "An adaptive dynamic scheduling technique for parallel loops on shared memory multiprocessor systems". Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=851.

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Thesis (M.S.)--West Virginia University, 1999.
Title from document title page. Document formatted into pages; contains viii, 82 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 77-79).

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35

Heng, Boon Liang. "Evaluating data averaging techniques for high gradient flow fields through uncertainty analysis". Master's thesis, Mississippi State : Mississippi State University, 2001. http://library.msstate.edu/etd/show.asp?etd=etd-07112001-105544.

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36

Higgins, K. "Comparison of engineering correlations for predicting heat transfer in zero-pressure-gradient compressible boundary layers with CFD and experimental data". Fishermans Bend, Victoria : Defence Science and Technology Organisation, 2008. http://hdl.handle.net/1947/9653.

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37

Price, Ralph J. "Modeling Three Reacting Flow Systems with Modern Computational Fluid Dynamics". Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1810.pdf.

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38

Fabiny, Larry. "Dynamics of a coupled solid state laser array". Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/30509.

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39

Bozorgzadeh, Manijeh. "Characterisation and determination of gas condensate dynamics from pressure transient data and fluid PVT properties". Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638817.

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40

Aljohani, Faraj Jaber R. "Improving Cooling Effectiveness in Air-Cooled Data Centres: Analysis and Assessment using Computational Fluid Dynamics". Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/75227.

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Datacentre efficiency becomes increasingly important as demand for IT infrastructure grows. This thesis presents detailed Computational Fluid Dynamics analyses of flow and heat transfer within typical raised floor datacentres. Compared with previous studies, greater understanding of the unsteady flow and heat transfer in datacentres resulted from using Scale-Adaptive turbulence modelling instead of a RANS approach. This led to a novel rack-level sub-cooler design, which was shown to allow higher volumetric heat generation rates within datacentres.

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41

Saber, Nikoo Rezazadeh. "CFD modelling of blood flow in the human left ventricle based on magnetic resonance imaging data". Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390806.

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42

Shi, Liming. "Computational Fluid Dynamics Simulation of Steam Reforming and Autothermal Reforming for Fuel Cell Applications". Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1234712316.

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43

Nagayama, Taisuke. "A new inversion method for the spectroscopic analysis of image data". abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1433297.

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44

Bertozzi, Barbara. "Feasibility study for understanding ice cave microclimate through thermo-fluid dynamics approaches". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.

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Ice caves are classified as sporadic permafrost phenomena and consist of lava tubes or cave systems in which perennial ice forms. Ice within caves can be very old and can carry important information on permafrost conditions, climate changes and past climates. Until now, these systems have been investigated mainly with an experimental approach. A critical topic in ice cave studies is the understanding of how the internal environment interacts with the external and how these systems react to changes in the external conditions. In this thesis, a new numerical approach to understand ice cave microclimate is proposed. Numerical studies can contribute greatly to a better understanding of the processes involved in the formation and preservation of the ice in cave. Furthermore, computational fluid dynamic methods can be a valuable support to define new experimental setups and to interpret experimental results. The cave studied in this work is Leupa ice cave, located in Friuli Venezia Giulia region. Air flows inside Leupa ice caves were characterized with an integrated approach using both experimental and numerical methods. A general approach was initially adopted and three representative days were identified to investigate which circulation patterns can develop under different environmental conditions. The comparison of numerical and experimental data permitted to evaluate the quality of the simulations and to identify the main problematics that need to be investigated further. Deeper investigations were then performed for a single day to investigate the temperature and boundary conditions effect on the flow thermo-dynamics inside the cave. New insights on the fluid-dynamic behavior of Leupa ice cave are achieved, showing that numerical methods could represent a powerful tool to study ice caves, improving and integrating the information that could be obtained from standard experimental measurements.

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45

Tian, Yu-Chu. "Dynamics analysis and integrated design of real-time control systems". School of Electrical and Information Engineering, 2009. http://hdl.handle.net/2123/5743.

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Doctor of Philosophy (PhD)
Real-time control systems are widely deployed in many applications. Theory and practice for the design and deployment of real-time control systems have evolved significantly. From the design perspective, control strategy development has been the focus of the research in the control community. In order to develop good control strategies, process modelling and analysis have been investigated for decades, and stability analysis and model-based control have been heavily studied in the literature. From the implementation perspective, real-time control systems require timeliness and predictable timing behaviour in addition to logical correctness, and a real-time control system may behave very differently with different software implementations of the control strategies on a digital controller, which typically has limited computing resources. Most current research activities on software implementations concentrate on various scheduling methodologies to ensure the schedulability of multiple control tasks in constrained environments. Recently, more and more real-time control systems are implemented over data networks, leading to increasing interest worldwide in the design and implementation of networked control systems (NCS). Major research activities in NCS include control-oriented and scheduling-oriented investigations. In spite of significant progress in the research and development of real-time control systems, major difficulties exist in the state of the art. A key issue is the lack of integrated design for control development and its software implementation. For control design, the model-based control technique, the current focus of control research, does not work when a good process model is not available or is too complicated for control design. For control implementation on digital controllers running multiple tasks, the system schedulability is essential but is not enough; the ultimate objective of satisfactory quality-of-control (QoC) performance has not been addressed directly. For networked control, the majority of the control-oriented investigations are based on two unrealistic assumptions about the network induced delay. The scheduling-oriented research focuses on schedulability and does not directly link to the overall QoC of the system. General solutions with direct QoC consideration from the network perspective to the challenging problems of network delay and packet dropout in NCS have not been found in the literature. This thesis addresses the design and implementation of real-time control systems with regard to dynamics analysis and integrated design. Three related areas have been investigated, namely control development for controllers, control implementation and scheduling on controllers, and real-time control in networked environments. Seven research problems are identified from these areas for investigation in this thesis, and accordingly seven major contributions have been claimed. Timing behaviour, quality of control, and integrated design for real-time control systems are highlighted throughout this thesis. In control design, a model-free control technique, pattern predictive control, is developed for complex reactive distillation processes. Alleviating the requirement of accurate process models, the developed control technique integrates pattern recognition, fuzzy logic, non-linear transformation, and predictive control into a unified framework to solve complex problems. Characterising the QoC indirectly with control latency and jitter, scheduling strategies for multiple control tasks are proposed to minimise the latency and/or jitter. Also, a hierarchical, QoC driven, and event-triggering feedback scheduling architecture is developed with plug-ins of either the earliest-deadline-first or fixed priority scheduling. Linking to the QoC directly, the architecture minimises the use of computing resources without sacrifice of the system QoC. It considers the control requirements, but does not rely on the control design. For real-time NCS, the dynamics of the network delay are analysed first, and the nonuniform distribution and multi-fractal nature of the delay are revealed. These results do not support two fundamental assumptions used in existing NCS literature. Then, considering the control requirements, solutions are provided to the challenging NCS problems from the network perspective. To compensate for the network delay, a real-time queuing protocol is developed to smooth out the time-varying delay and thus to achieve more predictable behaviour of packet transmissions. For control packet dropout, simple yet effective compensators are proposed. Finally, combining the queuing protocol, the packet loss compensation, the configuration of the worst-case communication delay, and the control design, an integrated design framework is developed for real-time NCS. With this framework, the network delay is limited to within a single control period, leading to simplified system analysis and improved QoC.

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46

Tian, Yu-Chu. "Dynamics analysis and integrated design of real-time control systems". Connect to full text, 2008. http://ses.library.usyd.edu.au/handle/2123/5743.

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Thesis (Ph. D.)--University of Sydney, 2009.
Title from title screen (viewed November 30, 2009). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Electrical and Information Engineering in the Faculty of Engineering & Information Technologies. Degree awarded 2009; thesis submitted 2008. Includes bibliographical references. Also available in print form.

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47

Fadel, Georges M. "Simulation of a domestic heat pump using a nonazeotropic working fluid and impact of parallel computers on the simulation of thermal systems". Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/19295.

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48

Cruz, Ethan E. "Coupled inviscid-viscous solution methodology for bounded domains: Application to data center thermal management". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54316.

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Computational fluid dynamics and heat transfer (CFD/HT) models have been employed as the dominant technique for the design and optimization of both new and existing data centers. Inviscid modeling has shown great speed advantages over the full Navier-Stokes CFD/HT models (over 20 times faster), but is incapable of capturing the physics in the viscous regions of the domain. A coupled inviscid-viscous solution method (CIVSM) for bounded domains has been developed in order to increase both the solution speed and accuracy of CFD/HT models. The methodology consists of an iterative solution technique that divides the full domain into multiple regions consisting of at least one set of viscous, inviscid, and interface regions. The full steady, Reynolds-Averaged Navier-Stokes (RANS) equations with turbulence modeling are used to solve the viscous domain, while the inviscid domain is solved using the Euler equations. By combining the increased speed of the inviscid solver in the inviscid regions, along with the viscous solver’s ability to capture the turbulent flow physics in the viscous regions, a faster and potentially more accurate solution can be obtained for bounded domains that contain inviscid regions which encompass more than half of the domain, such as data centers.

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49

Haffke, Peter [Verfasser]. "Dynamics of information processing in risky choices : Making thorough use of behavioral data / Peter Haffke". Konstanz : Bibliothek der Universität Konstanz, 2017. http://d-nb.info/1136864466/34.

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50

Goupil, Marc Y. "Dynamic Pressure Sensing for the Flight Test Data System". DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2115.

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Abstract (sommario):

This thesis describes the design, assembly, and test of the FTDS-K, a new device in the Boundary Layer Data System (BLDS) family of flight data acquisition systems. The FTDS-K provides high-frequency, high-gain data acquisition capability for up to two pressure sensors and an additional three low-frequency pressure sensors. Development of the FTDS-K was separated into a core module, specialized analog subsystem, and practical testing of the FTDS-K in a flow measurement mission. The core module combines an nRF52840-based microcontroller module, switching regulator, microSD card, real-time clock, temperature sensor, and trio of pressure sensors to provide the same capabilities as previous-generation BLDS-P devices. An expansion header is included in the core module to allow additional functionality to be added via daughter boards. An analog signal chain comprised of two-stage amplification and fourth-order active antialiasing filters was implemented as a daughter board to provide an AC-coupled end-to-end gain of 7,500 and a DC-coupled end-to-end gain of 50. This arrangement was tested in a wind tunnel to demonstrate that sensors with a full-scale range of 103 kPa can be used to reliably discriminate between laminar and turbulent flows based on pressure fluctuation differences on the order of tens of Pa. A combination of wind-off correction and band-filtering was used to reduce the effect of inherent and induced electrical noise, while two-sensor correlation was tested and shown to be effective at removing certain types of noise. Total power consumption for the FTDS-K in a representative mission is 208 mW, which translates to an operational endurance of 9 hours with 2 AAA LiFeS2 cells at -40°C.

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Tesi sul tema "Fluid dynamics – Data processing"

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