Tesis sobre el tema "Computational fluid dynamics"
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Hussain, Muhammad Imtiaz. "Computational fluid dynamics". Thesis, Aberystwyth University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257607.
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Ellam, Darren John. "Modelling smart fluid devices using computational fluid dynamics". Thesis, University of Sheffield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398597.
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Katz, Aaron Jon. "Meshless methods for computational fluid dynamics /". May be available electronically:, 2009. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Molale, Dimpho Millicent. "A computational evaluation of flow through porous media". Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/686.
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Pagliuca, Giampaolo. "Model reduction for flight dynamics using computational fluid dynamics". Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3029018/.
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The coupling of computational fluid dynamics and rigid body dynamics promises enhanced multidisciplinary simulation capability for aircraft design and certification. Industrial application of such coupled simulations is limited however by computational cost. In this context, model reduction can retain the fidelity of the underlying model while decreasing the overall computational effort. Thus, investigation of such coupled model reduction is presented in this thesis. The technique described herein relies on an expansion of the full order non-linear residual function in a truncated Taylor series and subsequent projection onto a small modal basis. Two procedures are outlined to obtain modes for the projection. First, flight dynamics eigenmodes are obtained with an operator-based identification procedure which is capable of calculating the global modes of the coupled Jacobian matrix related to flight dynamics without computing all the modes of the system. Secondly, proper orthogonal decomposition is used as a data-based method to obtain modes representing the coupled system subject to external disturbances such as gusts. Benefits and limitations of the two methods are investigated by analysing results for both initial and external disturbance simulations. Three test cases of increasing complexity are presented. First, an aerofoil, free to translate vertically and rotate, is investigated with aerodynamics based on the Euler equations. Secondly, a two-dimensional wing-tail configuration is studied for longitudinal dynamics. Aerodynamics is modelled with Reynolds-averaged Navier-Stokes equations and Spalart-Allmaras turbulence model. Thirdly, a three-dimensional industrial use case, which concerns a large civil aircraft, is investigated and longitudinal as well as lateral dynamics are both taken into account. Overall, reduced order models relying on both operator-based and data-based identifications are able to retain the accuracy of the high-fidelity tools to predict accurately flight dynamics responses and loads while reducing the computational cost by up to two orders of magnitude. If adopted, these techniques are expected to speed-up aircraft design and lowering certification costs with the final aim of reduced expense for airlines and, as a consequence, for flying passengers.
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Da, Ronch Andrea. "On the calculation of dynamic derivatives using computational fluid dynamics". Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/5513/.
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In this thesis, the exploitation of computational fluid dynamics (CFD) methods for the flight dynamics of manoeuvring aircraft is investigated. It is demonstrated that CFD can now be used in a reasonably routine fashion to generate stability and control databases. Different strategies to create CFD-derived simulation models across the flight envelope are explored, ranging from combined low-fidelity/high-fidelity methods to reduced-order modelling. For the representation of the unsteady aerodynamic loads, a model based on aerodynamic derivatives is considered. Static contributions are obtained from steady-state CFD calculations in a routine manner. To more fully account for the aircraft motion, dynamic derivatives are used to update the steady-state predictions with additional contributions. These terms are extracted from small-amplitude oscillatory tests. The numerical simulation of the flow around a moving airframe for the prediction of dynamic derivatives is a computationally expensive task. Results presented are in good agreement with available experimental data for complex geometries. A generic fighter configuration and a transonic cruiser wind tunnel model are the test cases. In the presence of aerodynamic non-linearities, dynamic derivatives exhibit significant dependency on flow and motion parameters, which cannot be reconciled with the model formulation. An approach to evaluate the sensitivity of the non-linear flight simulation model to variations in dynamic derivatives is described. The use of reduced models, based on the manipulation of the full-order model to reduce the cost of calculations, is discussed for the fast prediction of dynamic derivatives. A linearized solution of the unsteady problem, with an attendant loss of generality, is inadequate for studies of flight dynamics because the aircraft may experience large excursions from the reference point. The harmonic balance technique, which approximates the flow solution in a Fourier series sense, retains a more general validity. The model truncation, resolving only a small subset of frequencies typically restricted to include one Fourier mode at the frequency at which dynamic derivatives are desired, provides accurate predictions over a range of two- and three-dimensional test cases. While retaining the high fidelity of the full-order model, the cost of calculations is a fraction of the cost for solving the original unsteady problem. An important consideration is the limitation of the conventional model based on aerodynamic derivatives when applied to conditions of practical interest (transonic speeds and high angles of attack). There is a definite need for models with more realism to be used in flight dynamics. To address this demand, various reduced models based on system-identification methods are investigated for a model case. A non-linear model based on aerodynamic derivatives, a multi-input discrete-time Volterra model, a surrogate-based recurrence-framework model, linear indicial functions and radial basis functions trained with neural networks are evaluated. For the flow conditions considered, predictions based on the conventional model are the least accurate. While requiring similar computational resources, improved predictions are achieved using the alternative models investigated. Furthermore, an approach for the automatic generation of aerodynamic tables using CFD is described. To efficiently reduce the number of high-fidelity (physics-based) analyses required, a kriging-based surrogate model is used. The framework is applied to a variety of test cases, and it is illustrated that the approach proposed can handle changes in aircraft geometry. The aerodynamic tables can also be used in real-time to fly the aircraft through the database. This is representative of the role played by CFD simulations and the potential impact that high-fidelity analyses might have to reduce overall costs and design cycle time.
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Paton, Jonathan. "Computational fluid dynamics and fluid structure interaction of yacht sails". Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/14036/.
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This thesis focuses on the numerical simulation of yacht sails using both computational fluid dynamics (CFD) and fluid structure interaction (FSI) modelling. The modelling of yacht sails using RANS based CFD and the SST turbulence model is justified with validation against wind tunnel studies (Collie, 2005; Wilkinson, 1983). The CFD method is found to perform well, with the ability to predict flow separation, velocity and pressure profiles satisfactorily. This work is extended to look into multiple sail interaction and the impact of the mast upon performance. A FSI solution is proposed next, coupling viscous RANS based CFD and a structural code capable of modelling anistropic laminate sails (RELAX, 2009). The aim of this FSI solution is to offer the ability to investigate sails' performance and flying shapes more accurately than with current methods. The FSI solution is validated with the comparison to flying shapes of offwind sails from a bespoke wind tunnel experiment carried out at the University of Nottingham. The method predicted offwind flying shapes to a greater level of accuracy than previous methods. Finally the CFD and FSI solution described here above is showcased and used to model a full scale Volvo Open 70 racing yacht, including multiple offwind laminate sails, mast, hull, deck and twisted wind profile. The model is used to demonstrate the potential of viscous CFD and FSI to predict performance and aid in the design of high performance sails and yachts. The method predicted flying shapes and performance through a range of realistic sail trims providing valuable data for crews, naval architects and sail designers.
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Parolini, Nicola. "Computational fluid dynamics for naval engineering problems /". [S.l.] : [s.n.], 2004. http://library.epfl.ch/theses/?nr=3138.
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Rüther, Nils. "Computational Fluid Dynamics in Fluvial Sedimentation Engineering". Doctoral thesis, Norwegian University of Science and Technology, Department of Hydraulic and Environmental Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1917.
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The present dissertation describes the improvement of a numerical model when predicting sedimentation and erosion processes in fluvial geomorphology. Various algorithms and parameters were implemented in a computational fluid dynamic model for simulation of three-dimensional water flow and coupled sediment transport to gain an insight into the capabilities of the numerical model. Within the scope of the test cases the model simulated suspended load concentrations at a water intake, transient bed deformation in a 90º channel bend, grain sorting processes as well as an unsteady flow regime in a 180º channel bend, transient bed deformation in a sine-shaped meandering channel with occurring bed forms and the free-forming meander evolution of an initially straight channel. All results matched well with the measurements. The results also showed that using computational fluid dynamics for modeling water flow and sediment transport is one step closer of having a universal predictor for processes in fluvial geomorphology. However, there are limitations and some uncertainties in computing the water surface location and alluvial roughness as well as in turbulence modeling. These should be clarified in future investigations.
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Demir, H. Ozgur. "Computational Fluid Dynamics Analysis Of Store Separation". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605294/index.pdf.
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In this thesis, store separation from two different configurations are solved using computational methods. Two different commercially available CFD codesCFD-FASTRAN, an implicit Euler solver, and an unsteady panel method solver USAERO, coupled with integral boundary layer solution procedure are used for the present computations. The computational trajectory results are validated against the available experimental data of a generic wing-pylon-store configuration at Mach 0.95. Major trends of the separation are captured. Same configuration is used for the comparison of unsteady panel method with Euler solution at Mach 0.3 and 0.6. Major trends are similar to each other while some differences in lateral and longitudinal displacements are observed. Trajectories of a fueltank separated from an F-16 fighter aircraft wing and full aircraft configurations are found at Mach 0.3 using only the unsteady panel code. The results indicate that the effect of fuselage is to decrease the drag and to increase the side forces acting on the separating fueltank from the aircraft. It is also observed that the yawing and rolling directions of the separating fueltank are reversed when it is separated from the full aircraft configuration when compared to the separation from the wing alone configuration.
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Sjöström, Kalle. "Computational Fluid Dynamics in 2D Game Environments". Thesis, Umeå universitet, Institutionen för datavetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-48078.
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Games are becoming increasingly realistic. Real-time physics simulation were almost unimaginable just decades ago but are now a vital part of many games. Even dynamic physics simulation e.g. interactive fluids has found a place in game development.This paper investigates and evaluates three methods of simulating fluids with the purpose of testing these in a 2dgame environment. These methods are allLagrangian i.e. particlebased, Sph methods, and chosen because of their dierences but also their importance to the field of interactive fluid simulation. In order to integrate the methods, they will be implemented with use of the 2dmechanics engineBox2dwhich is a popular choice in 2d game development.To evaluate the methods, water is the flluid of choice. Water is the most abundant of fluids and is bound to be found in most games containing fluids. Water is almost incompressible, therefore, the methods ability to withhold incompressibility is tested. Also, the convergence properties of kinetic energy is tested in order to find out more about stability.The results showed that the method based on Muller et al. [2003] demanded a prohibitively small time-step to be especially useful. The method from Clavet et al. [2005] managed to keep a suficiently large time-step but failed in simulating incompressible low-viscosity fluids. However, it excelled in the simulation of highly viscous fluids like gel. Finally, the method based on Bodin et al. [2011] showed impressive result in incompressibility but is more difficult to implement and requires a bit more resources and run-time.The paper concludes that if easy-to-implement cool effect is sought, then the method of Clavet et al. [2005] could be used with great results. However, Bodin et al. [2011] would be the best choice for games where physical accuracy is of greater importance. Also, Box2d is a good choice to extend with a fluid engine. However, it will never be as good as creating a physics engine with an integrated fluid engine.
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Kardos, T. N. "Modelling Smoke Flow Using Computational Fluid Dynamics". University of Canterbury. Civil Engineering, 1996. http://hdl.handle.net/10092/8278.
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There have been a number of experimental investigations into the backdraft phenomena. A backdraft occurs in the event of a ventilation source being formed in a compartment, within which a fire has been burning for a sufficiently long enough time to form a deep layer of excess pyrolyzates. The source of fresh air will flow into the compartment in the form of a gravity current. It is the gravity current feature of backdrafts that this research project focuses on.
Application of Computational Fluid Dynamics (CFD) to fire problems is expanding, including the development of specific programs for fire engineering applications. The experimental programme that was used in this research project highlights the difficulties of analysing fluid flows by using CFD simulations. The Flow3D program was used to obtain a more detailed understanding of the behaviour of a gravity current, allowing a detailed study of fluid dynamics which cannot be investigated experimentally. The simulations used two different vent configurations, with the CFD model being validated on the experimental results of salt water tank models. The simulations preformed compared well to the experimental data that was used for scaled salt water tank experiments.
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Cusdin, P. A. "Automatic sensitivity code for computational fluid dynamics". Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431586.
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Gilkeson, Natalie Ariana. "Computational fluid dynamics simulations of personalised ventilation". Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21947/.
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Personalised ventilation (PV) systems create a micro- climate around individuals in indoor environments, and they have the potential to improve personal comfort, indoor air quality and productivity of building occupants. The focus of the research undertaken in this Ph.D was to determine whether the use of PV strategies can enhance thermal comfort and air quality compared to a traditional displacement ventilation technique. The studies were simulation based and considered multiple configurations, with the methods validated against a benchmark test case. Computational Fluid Dynamics (CFD) simulations modelled the deployment of clean air to a seated computational thermal manikin (CTM) in a mechanically ventilated chamber. The effects of radiation were accounted for using the Discrete Ordinates (DO) model which enhanced the prediction of thermal properties in the domain. High-fidelity CFD simulations were computed on meshes of 5.4 million cells for single CTM cases and up to 9.4 million cells for two CTMs. Solutions were generated using the transition SST turbulence model which accounted for the range of Reynolds numbers from laminar to turbulent, in every single flow field. Results showed that PV jet temperature and its proximity to a CTM face influences airflow patterns which in turn impacts the levels of thermal comfort and indoor air quality seen. It is important to use realistically shaped CTMs in conjunction with the heat flux thermal boundary condition if details of the flow and thermal comfort is important. In contrast, where details of the flow field in small spaces are unimportant, a simplified CTM in the form of an upright cylinder is suitable, simplifying the modelling process. A PV jet with no thermal mass in the domain can give an indication of where best to place the PV nozzle, for a given set of conditions. For simulations using realistic CTM shapes, there exists a strong interaction between the PV jet, the convective boundary layer around the CTM and the thermal plume. If the PV jet is placed too far away from the CTM (outside of the zone of flow establishment), air quality can be impaired and may lead to worse air quality than room ventilation alone. Extending the work to two CTMs in a room highlighted the fact that both thermal plumes tended to move towards each other with the strength of attraction greater when the CTMs were in closer proximity. This mutual plume attraction phenomenon set up two large recirculation currents in the room which were somewhat different to the single CTM flow fields. Overall, a significant conclusion from this research is that PV systems can be very effective for improving air quality and thermal comfort if used appropriately, however they can also prove to be detrimental to the overall indoor environment when poorly placed.
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Huismann, Immo. "Computational fluid dynamics on wildly heterogeneous systems". TUDPress, 2018. https://tud.qucosa.de/id/qucosa%3A74002.
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In the last decade, high-order methods have gained increased attention. These combine the convergence properties of spectral methods with the geometrical flexibility of low-order methods. However, the time step is restrictive, necessitating the implicit treatment of diffusion terms in addition to the pressure. Therefore, efficient solution of elliptic equations is of central importance for fast flow solvers. As the operators scale with O(p · N), where N is the number of degrees of freedom and p the polynomial degree, the runtime of the best available multigrid algorithms scales with O(p · N) as well. This super-linear scaling limits the applicability of high-order methods to mid-range polynomial orders and constitutes a major road block on the way to faster flow solvers.
This work reduces the super-linear scaling of elliptic solvers to a linear one. First, the static condensation method improves the condition of the system, then the associated operator is cast into matrix-free tensor-product form and factorized to linear complexity. The low increase in the condition and the linear runtime of the operator lead to linearly scaling solvers when increasing the polynomial degree, albeit with low robustness against the number of elements. A p-multigrid with overlapping Schwarz smoothers regains the robustness, but requires inverse operators on the subdomains and in the condensed case these are neither linearly scaling nor matrix-free. Embedding the condensed system into the full one leads to a matrix-free operator and factorization thereof to a linearly scaling inverse. In combination with the previously gained operator a multigrid method with a constant runtime per degree of freedom results, regardless of whether the polynomial degree or the number of elements is increased.
Computing on heterogeneous hardware is investigated as a means to attain a higher performance and future-proof the algorithms. A two-level parallelization extends the traditional hybrid programming model by using a coarse-grain layer implementing domain decomposition and a fine-grain parallelization which is hardware-specific. Thereafter, load balancing is investigated on a preconditioned conjugate gradient solver and functional performance models adapted to account for the communication barriers in the algorithm. With the new model, runtime prediction and measurement fit closely with an error margin near 5 %.
The devised methods are combined into a flow solver which attains the same throughput when computing with p = 16 as with p = 8, preserving the linear scaling. Furthermore, the multigrid method reduces the cost of implicit treatment of the pressure to the one for explicit treatment of the convection terms. Lastly, benchmarks confirm that the solver outperforms established high-order codes.
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Corey, Kenneth P. "Airgun pellet performance using computational fluid dynamics /". Online version of thesis, 1994. http://hdl.handle.net/1850/11690.
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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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Stipcich, Goran. "High-order methods for computational fluid dynamics". Doctoral thesis, Università degli studi di Trieste, 2012. http://hdl.handle.net/10077/7764.
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2010/2011In the past two decades, the growing interest in the study of fluid flows involving discontinuities, such as shocks or high gradients, where a quadratic-convergent method may not provide a satisfactory solution, gave a notable impulse to the employment of high-order techniques. The present dissertation comprises the analysis and numerical testing of two high-order methods. The first one, belonging to the discontinuous finite-element class, is the discontinuous control-volume/finite-element method (DCVFEM) for the advection/ diffusion equation. The second method refers to the high-order finite-difference class, and is the mixed weighted non-oscillatory scheme (MWCS) for the solution of the compressible Euler equations. The methods are described from a formal point of view, a Fourier analysis is used to assess the dispersion and dissipation errors, and numerical simulations are conducted to confirm the theoretical results.
XXIV Ciclo
1980
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Holland, David M. "Nano-scale computational fluid dynamics with molecular dynamics pre-simulations". Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/72851/.
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A procedure for using Molecular Dynamics (MD) simulations to provide essential fl uid and interface properties for subsequent use in Computational Fluid Dynamics (CFD) calculations of nano-scale fluid fl ows is presented. The MD presimulations enable an equation of state, constitutive relations, and boundary conditions to be obtained for any given fl uid/solid combination, in a form that can be conveniently implemented within an otherwise conventional Navier-Stokes solver. The results presented demonstrate that these enhanced CFD simulations are capable of providing good fl ow field results in a range of complex geometries at the nano-scale. Comparison for validation is with full-scale MD simulations here, but the computational cost of the enhanced CFD is negligible in comparison with the MD. It is shown that this enhanced CFD can predict unsteady nano-scale ows in non-trivial geometries. A converging-diverging nano-scale channel is modelled where the fl uid fl ow is driven by a time-varying body force. The time-dependent mass fl ow rate predicted by the enhanced CFD agrees well with a MD simulation of the same configuration. Conventional CFD predictions of the same case are wholly inadequate. It is demonstrated that accurate predictions can be obtained in geometries that are more complex than the planar MD pre-simulation geometry that provides the nano-scale fl uid properties. The robustness of the enhanced CFD is tested by application to water fl ow along a (15,15) carbon nanotube (CNT) and it is found that useful fl ow information can be obtained. The enhnaced CFD model is applied as a design optimisation tool on a bifurcating two-dimensional channel, with the target of maximising mass fl ow rate for a fixed total volume and applied pressure. At macro scales the optimised geometry agrees well with Murray's law for optimal branching of vascular networks; however, at the nano-scale, the optimum result deviates from Murray's law, and a corrected equation is presented. However, it is found that as the mass flow rate increases through the channel high pressure losses occur at the junction of the network. These high pressure losses also have an impact on the optimal design of a network.
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Chambers, Steven B. "Investigation of combustive flows and dynamic meshing in computational fluid dynamics". Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/1324.
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Computational Fluid Dynamics (CFD) is a field that is constantly advancing. Its advances in terms of capabilities are a result of new theories, faster computers, and new numerical methods. In this thesis, advances in the computational fluid dynamic modeling of moving bodies and combustive flows are investigated. Thus, the basic theory behind CFD is being extended to solve a new class of problems that are generally more complex. The first chapter that investigates some of the results, chapter IV, discusses a technique developed to model unsteady aerodynamics with moving boundaries such as flapping winged flight. This will include mesh deformation and fluid dynamics theory needed to solve such a complex system. Chapter V will examine the numerical modeling of a combustive flow. A three dimensional single vane burner combustion chamber is numerically modeled. Species balance equations along with rates of reactions are introduced when modeling combustive flows and these expressions are discussed. A reaction mechanism is validated for use with in situ reheat simulations. Chapter VI compares numerical results with a laminar methane flame experiment to further investigate the capabilities of CFD to simulate a combustive flow. A new method of examining a combustive flow is introduced by looking at the solutions ability to satisfy the second law of thermodynamics. All laminar flame simulations are found to be in violation of the entropy inequality.
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Liu, Li. "Computational fluid dynamics modelling of complex fluid flow in stirred vessels". Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4753/.
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Fluid mixing in stirred vessels is widely encountered in a number of industries. In this work, different experimental techniques and the CFD modelling approach are used to measure the mixing of a wide range of fluids in stirred vessels. As the detailed validation is essential for CFD modelling, CFD predictions are compared in detail with different experimental measurements. The capability of CFD modelling of the 3D spatial distribution of velocity and solid concentration within opaque concentrated solid-liquid suspensions with the mean solid concentration up to 40 wt% is assessed by comparing with the experimental data obtained from positron emission particle tracking (PEPT) measurements. Because the impeller configuration is of significant importance to the flow pattern, the performance of different impellers for single-phase mixing of Newtonian and non-Newtonian fluids in stirred vessels is compared. CFD predictions of flow fields generated from different impellers are compared with those measured by the well-established particle image velocimetry (PIV) technique. The capability of CFD modelling of different mixing features of non-Newtonian fluids in stirred vessels are verified by comparing with experimental data obtained from PIV, PEPT, and planar laser induced fluorescence (PLIF) measurements.
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Ichinose, Matthew Hiroki. "Fluid Agitation Studies for Drug Product Containers using Computational Fluid Dynamics". DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1980.
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At Amgen, the Automated Vision Inspection (AVI) systems capture the movement of unwanted particles in Amgen's drug product containers. For quality inspection, the AVI system must detect these undesired particles using a high speed spin-stop agitation process. To better understand the fluid movements to swirl the particles away from the walls, Computational Fluid Dynamics (CFD) is used to analyze the nature of the two phase flow of air and a liquid solution.
Several 2-D and 3-D models were developed using Fluent to create simulations of Amgen's drug product containers for a 1 mL syringe, 2.25 mL syringe, and a 5 mL cartridge. Fluid motion and potential bubble formations were studied within the liquid/gas domain inside the container by varying parameters such as viscosity, angular velocity, and surface tension. Experiments were conducted using Amgen's own equipment to capture the images of the spin-stop process and validate the models created in Fluent. Observations were made to see the effects of bubble formation or splashing during spin-down to rest.
The numerical and experimental results showed favorable comparison when measuring the meniscus height or the surface profile between the air and liquid. Also, at high angular velocity and dynamic viscosity, the container experiences instabilities and bubble formations. These studies indicate that CFD can be used as an useful and important tool to study fluid movement during agitation and observe any undesirable results for quality inspection.
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Soudah, Prieto Eduardo. "Computational fluid dynamics indicators to improve cardiovascular pathologies". Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/392613.
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In recent years, the study of computational hemodynamics within anatomically complex vascular regions has generated great interest among clinicians.
The progress in computational fluid dynamics, image processing and high-performance computing haveallowed us to identify the candidate vascular regions for the appearance of cardiovascular diseases and to predict how this disease may evolve.
Medicine currently uses a paradigm called diagnosis. In this thesis we attempt to introduce into medicine the predictive paradigm that has been used in engineering for many years. The objective of this thesis is therefore to develop predictive models based on diagnostic indicators for cardiovascular pathologies.
We try to predict the evolution of aortic abdominal aneurysm, aortic coarctation and coronary artery disease in a personalized way for each patient. To understand how the cardiovascular pathology will evolve and when it will become a health risk, it is necessary to develop new technologies by merging medical imaging and computational science. We propose diagnostic indicators that can improve the diagnosis and predict the evolution of the disease more efficiently than the methods used until now. In particular, a new methodology for computing diagnostic indicators based on computational hemodynamics and medical imaging is proposed. We have worked with data of anonymous patients to create real predictive technology that will allow us to continue advancing in personalized medicine and generate more sustainable health systems. However, our final aim is to achieve an impact at a clinical level. Several groups have tried to create predictive models for cardiovascular pathologies, but they have not yet begun to use them in clinical practice. Our objective is to go further and obtain predictive variables to be used practically in the clinical field.
It is to be hoped that in the future extremely precise databases of all of our anatomy and physiology will be available to doctors. These data can be used for predictive models to improve diagnosis or to improve therapies or personalized treatments.En els últims anys, l'estudi de l'hemodinàmica computacional en regions vasculars anatòmicament complexes ha generat un gran interès entre els clínics. El progrés obtingut en la dinàmica de fluids computacional, en el processament d'imatges i en la computació d'alt rendiment ha permès identificar regions vasculars on poden aparèixer malalties cardiovasculars, així com predir-ne l'evolució. Actualment, la medicina utilitza un paradigma anomenat diagnòstic. En aquesta tesi s'intenta introduir en la medicina el paradigma predictiu utilitzat des de fa molts anys en l'enginyeria. Per tant, aquesta tesi té com a objectiu desenvolupar models predictius basats en indicadors de diagnòstic de patologies cardiovasculars. Tractem de predir l'evolució de l'aneurisma d'aorta abdominal, la coartació aòrtica i la malaltia coronària de forma personalitzada per a cada pacient. Per entendre com la patologia cardiovascular evolucionarà i quan suposarà un risc per a la salut, cal desenvolupar noves tecnologies mitjançant la combinació de les imatges mèdiques i la ciència computacional. Proposem uns indicadors que poden millorar el diagnòstic i predir l'evolució de la malaltia de manera més eficient que els mètodes utilitzats fins ara. En particular, es proposa una nova metodologia per al càlcul dels indicadors de diagnòstic basada en l'hemodinàmica computacional i les imatges mèdiques. Hem treballat amb dades de pacients anònims per crear una tecnologia predictiva real que ens permetrà seguir avançant en la medicina personalitzada i generar sistemes de salut més sostenibles. Però el nostre objectiu final és aconseguir un impacte en l¿àmbit clínic. Diversos grups han tractat de crear models predictius per a les patologies cardiovasculars, però encara no han començat a utilitzar-les en la pràctica clínica. El nostre objectiu és anar més enllà i obtenir variables predictives que es puguin utilitzar de forma pràctica en el camp clínic. Es pot preveure que en el futur tots els metges disposaran de bases de dades molt precises de tota la nostra anatomia i fisiologia. Aquestes dades es poden utilitzar en els models predictius per millorar el diagnòstic o per millorar teràpies o tractaments personalitzats.
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Jayaraman, Balaji. "Computational modeling of glow discharge-induced fluid dynamics". [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015702.
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Hovland, Svein. "Model Reduction and Control in Computational Fluid Dynamics". Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2333.
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ROUSSEAU, Yannick, Igor MEN'SHOV y Yoshiaki NAKAMURA. "Morphing-Based Shape Optimization in Computational Fluid Dynamics". 日本航空宇宙学会, 2007. http://hdl.handle.net/2237/13876.
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Lukes, Richard Angus. "Improving track cycling performance using computational fluid dynamics". Thesis, University of Sheffield, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505805.
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Deng, Xiaolong. "APPLICATIONS OF COMPUTATIONAL FLUID DYNAMICS TO PLANETARY ATMOSPHERES". UKnowledge, 2009. http://uknowledge.uky.edu/gradschool_diss/711.
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Computational Fluid Dynamics (CFD) has been applied to many areas. As one of the most important fluids, the atmosphere is closely related to people’s life. Studying the atmospheres on other planets can help people understand the Earth’s atmosphere and the climate and weather phenomena in it. Because of the complexity of a planetary atmosphere and the limitation of observations, applying CFD to the study of planetary atmospheres is becoming more and more popular. This kind of CFD simulations will also help people design the mission to the extra planets.
In this dissertation, through CFD simulations, we studied the three important phenomena in a planetary atmosphere: vortices, zonal winds and clouds. The CFD model Explicit Planetary Isentropic Coordinate (EPIC) Global Circulation Model (GCM) was applied in these simulations. Dynamic simulations of the Great Dark Spots (GDS) on Neptune and the Uranian Dark Spot (UDS) were performed. In this work, constructed zonal wind profiles and vertical pressure-temperature profile were constructed based on the observational data. Then, we imported a two-flux radiation model with two-band absorption coefficients into EPIC to study the seasonal changes on Uranus. Finally, a methane cloud model was imported to study the cloud formation around a great vortex and its effects on the vortex.
In the process of the dynamic simulations of Neptune’s atmosphere and its vortices in it, the parameters about the background and the vortex itself were investigated to try to fit the observational results. We found that a small gradient of background absolute vorticity near a GDS is needed to sustain a great vortex in the atmosphere. The drift rate and oscillations of a GDS are closely related to the zonal wind profile and the vortex characteristics. The dynamic simulations of the UDS suggested why it is hard to observe a great vortex on Uranus and indicated that a region of near constant absolute vorticity appearing at ∼28◦N in the zonal wind profile is possibly recommended to the sustainability of the UDS.With the two-flux radiation model, we simulated the seasonal change of the zonal wind profile on Uranus. The observational temperature distribution and global convection were also achieved. With the methane cloud model, we simulated the poleward cloud above great vortices on both Neptune and Uranus. The results suggested that the cloud model can help the GDS on Neptune to keep its shape and moderate its oscillations. Similarly, it can also help the UDS to keep its form.
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Upadhyay, Drona Raj. "Low head turbine development using computational fluid dynamics". Thesis, Nottingham Trent University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403093.
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Gallagher, P. "Slam simulations : An application of computational fluid dynamics". Thesis, University of Glasgow, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378158.
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Aharon, Ofer S. M. Massachusetts Institute of Technology. "Stress distributions around hydrofoils using computational fluid dynamics". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46382.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaf 108).
This research describes the reciprocal influence between two foils, vertically and horizontally oriented, on each other for different gaps between them. Those cases are the focus part of a bigger process of lowering significantly the drag of a ship when hydrofoils are attached to its hull. The research results are based on CFD analyses using the ADINA software. In order to verify the CFD process, a comparison was made between analytical, experimental and ADINA?s results for a single foil. The chosen foil was the famous Clark-Y foil; however a correction to its geometry was made using the Unigraphics software. Using the corrected geometry with an analytical solution well detailed and explained, the results of the CFD model were compared to experimental and analytical solutions. The matching of the results and the obtained accuracy are very high and satisfactory. In addition, the research contains an examination of the results when one of the boundary conditions is changed. Surprisingly, it was discovered that the FREE slip condition along the foil is much closer to reality than the NO slip condition. Another examination was stretching horizontally the foil and checking the pressure distribution behavior. Those results met exactly the expectations. As for the main core of this research, both the bi-plane case and the stagger case were found to be less effective than using a single foil. The conclusion of those investigations is that using those cases a few decades ago was for a structural reason rather than stability or speed. Since this research is very wide but also deep in its knowledge, references and academic work, many future research works may be based on it or go on from its detailed stages.
by Ofer Aharon.
S.M.
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Chow, Yi-Mei Maria 1974. "Computational fluid dynamics for high performance structural facilities". Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50366.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.Includes bibliographical references (leaves 104-106).
by Yi-Mei Maria Chow.
M.Eng.
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McGlashan, Laurence Robert. "Coupling population balances to computational fluid dynamics solvers". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607919.
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Ji, Yingchun. "Computational fluid dynamics modelling of displacement natural ventilation". Thesis, De Montfort University, 2005. http://hdl.handle.net/2086/4951.
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Natural ventilation is widely recognised as contributing towards low-energy building design. The requirement to reduce energy usage in new buildings has rejuvenated interest in natural ventilation. This thesis deals with computer modelling of natural displacement ventilation driven either by buoyancy or buoyancy combined with wind forces. Two benchmarks have been developed using computational fluid dynamics (CFD) in order to evaluate the accuracy with which CFD is able to model natural displacement ventilation flow. The first benchmark considers the natural ventilation of a single ventilated space with high and low level openings connected to the exterior driven by combined forces of wind and buoyancy. The second benchmark considers natural ventilation flow in a single space connected to an atrium driven by pure buoyancy. Simulation results of key ventilation parameters (stratification depth, temperature gradient and ventilation flow rate) have been compared with analytical and experimental models and close agreements have been achieved. The two benchmarks are defined using the RNG k-epsilon turbulence model. A pressure boundary is applied onto the ventilation openings directly and a porous medium boundary is used to assist the development of the thermal plume. This method has proved to be robust and the close agreement between the three modelling techniques indicates that CFD is able to model natural ventilation flows in simple geometries with acceptable accuracy and reliability. Using the benchmarks the influences of key CFD modelling parameters and building design issues have been investigated. For example, representing openings, heat source representation, stack height, and air inlet strategies. Natural displacement ventilation of a multi-storey building comprising an atrium is also addressed. Simple analytical models have been developed to describe the key air flow features within the ventilation system.
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Chiu, Ya-Tien. "Computational Fluid Dynamics Simulations of Hydraulic Energy Absorber". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/34775.
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Hydraulic energy absorbers may be described as high-loss centrifugal turbomachines arranged to operate as stalled torque converters. The device absorbs the kinetic energy of a vehicle in motion and dissipates the energy into water. A steady, single-phase, Computational Fluid Dynamics (CFD) simulation has been performed to investigate the flow field in a hydraulic energy absorber. It was determined that to better predict the performance of the energy absorber, more sophisticated modeling approaches may be needed.
In this research, a steady, two-phase calculation with basic turbulence modeling was used as a first assessment. The two-phase model was used to investigate cavitation effects. Unsteady and advanced turbulence modeling techniques were then incorporated into single-phase calculations. The Multiple Reference Frame (MRF) Technique was used to model the interaction between the rotor and the stator. The calculations provided clearer details of the flow field without dramatically increasing the computational cost.
It was found that unsteady modeling was necessary to correctly capture the close coupling between the rotor and the stator. The predicted torque in the unsteady calculations was 70% of the experimental value and twice of the result in the steady-state calculations. It was found that the inaccuracy of torque prediction was due to (1) high pressures in the regions with complicated geometrical boundaries and, (2) dynamic interactions between the rotor and the stator were not captured fully. It was also determined that the unrealistically low pressure values were not caused by the physical cavitation, but by the lack of proper boundary conditions for the model. Further integration of the modeling techniques studied would improve the CFD results for use in the design of the energy absorber.Master of Science
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Hassan, Gasser Elhussin Gad Elrab. "Computational fluid dynamics in industrial and environmental applications". Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.713496.
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In recent years, natural gas has taken over from coal and it has become the second energy source after oil. This is not only because of its economic attractiveness, but also due to environmental concerns. This study is concerned with developing accurate Computational Fluid Dynamics (CFD) numerical models to study two different natural gas combustion systems, namely central heating domestic boilers and thermal cracking furnaces in petrochemical industries, in which the turbulence and the chemical kinetics play a similar role in importance. The first part of the thesis is concerned with developing accurate two-dimensional and three-dimensional CFD models to simulate the premixed flame produced in domestic boilers with a conventional cylindrical premix burner. The second part of the thesis is concerned with developing a three-dimensional CFD model to simulate the turbulent diffusion flame on the fire-side of the radiation section of thermal cracking test furnace coupled with a non-premixed low NO„ floor burner. Although, these two systems produce two different tying of flames, premixed and diffusion, and are used on two different scales in process beating applications, 30 kW and 6 MW, for both of the two systems, the turbulent mixing rate and the chemical reaction rates have comparable values and hence this should be considered in the model. Different combustion models, such as the pre-assumed PDF model with equilibrium chemistry and Eddy Dissipation Concept (EDC) with the detailed GRI 2.11 reaction mechanism, are used to simulate the turbulence-chemistry interactions inside the two combustion systems. Also, The effects of using different turbulence and radiation models and different reaction mechanisms on the accuracy of the predicted results are investigated. For the premixed flame inside domestic boilers, the CFD numerical results are compared with the experimental measurements at different boiler loads to investigate the accuracy of different CFD models. The most accurate validated CFD model is used to investigate the effect of different operating conditions on CO and NO emissions. Furthermore, the design of the 10 kW burner is modified in order to reduce the CO and NO emissions produced from the boiler.
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McClure, Dale David. "Modelling Bubble Column Bioreactors Using Computational Fluid Dynamics". Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12058.
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Bubble columns are widely used in the bio-processing industry to perform large scale, aerobic fermentations. For this reason, there is a clear interest in optimising both the design and operation of such reactors. One cost-effective approach is the development of a Computational Fluid Dynamics (CFD) model of the process; the major advantage of this methodology being that it provides detailed information about the flow patterns within the column, knowledge which is difficult to experimentally obtain at an industrial scale. Such data are of particular value as it has been conjectured that poor distribution of nutrients leads to a reduction in the process yield. Hence, the aim of this work was the development of a CFD model capable of accurately describing flow in bubble columns operated in the industrially relevant heterogeneous flow regime (i.e. at superficial velocities greater than 0.1 m/s). In order to develop and validate such a model, it was necessary to obtain experimental data for both an air/water system as well as an air/fermentation media system, the latter being a topic rarely examined in the literature. Hence, a comprehensive experimental program was undertaken at both the bench-top (using a column 0.19 m in diameter and 1 m in height) and pilot-scales (using a column 0.39 m in diameter and 2 m in height). A comprehensive experimental dataset consisting of measurements of the mixing time, overall hold-up, bubble size distribution, as well as profiles of the local hold-up, liquid velocity and gas velocity was generated. Both experimental configurations were modelled using CFD; with the model predictions being in satisfactory agreement with the experimental data at both scales. The development of a predictive model capable of accurately describing the complex mixing patterns in bubble columns (both with and without the presence of surfactants) operating in the heterogeneous flow regime is seen as a key step in the design and optimisation of such systems.
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Morris, Paul. "Computational fluid dynamics modelling of coronary artery disease". Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11772/.
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Background Coronary artery disease (CAD) is the leading cause of death in the world. Physiological lesion assessment with indices such as fractional flow reserve (FFR) is now accepted as the invasive gold-standard for diagnosing the significance of CAD and for guiding treatment. Patients undergoing percutaneous coronary intervention (PCI) guided by FFR have better clinical outcomes than those undergoing standard assessment. Furthermore, FFR-guided PCI is associated with decreased stent implantation and reduced long-term cost. Only a minority of patients undergoing invasive coronary angiography are currently afforded these benefits due to a number of procedure, operator, and economic related factors. There may be additional benefits from combined pressure and flow measurement. There is therefore a need for a technology that delivers the benefits of physiological lesion assessment without the factors which limit use of the invasive technique. Hypothesis Computational fluid dynamics (CFD) modelling based upon invasive coronary angiographic images (ICA) can characterise and predict intracoronary physiology. Aims (i) To develop a CFD-based model capable of simulating and predicting clinically relevant intracoronary physiology and (ii) validate model performance using clinical data from patients with CAD. Methods A workflow, based upon 3-D CFD modelling, capable of predicting intracoronary pressure and ‘virtual’ FFR from ICA, was developed. The model was validated against in vivo clinical measurements in 35 unique arterial datasets. The model predicted physiological lesion significance with 97% overall accuracy. Computation was prolonged (>24hrs). Two novel methods for solving the 3-D CFD were therefore developed. These methods enabled accurate computation of results in clinically tractable timescales (<5mins), at least equivalent to invasive measurement. The critical influence of system boundary conditions was explored, characterised, and quantified. A novel approach to patient-specific tuning of the outlet boundary conditions was developed and evaluated. The workflow was adapted to compute the pressure-flow relationship from measured pressure boundary conditions within a fully patient-specific in silico model. Results were validated within a novel experimental flow circuit incorporating patient-specific 3-D printed coronary arterial phantom models. Conclusions It is possible to compute clinically relevant intracoronary physiology (pressure or flow) from ICA. Results can be generated in clinically tractable timescales. The CFD model can be tuned to individual patient characteristics. The developed tools may be commercially desirable. Prior to full clinical translation, the model must be evaluated in a clinical trial.
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Patil, Anand. "Computational Simulation of Fluid Dynamics in Thin Films". Scholarship @ Claremont, 2001. https://scholarship.claremont.edu/hmc_theses/132.
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We investigate the formation of droplets in a thin liquid film on a solid substrate due to the combined action of surface tension and van der Waals forces. Current models for droplet formation assume that droplets have a shallow profile. By removing that assumption and numerically solving for stable droplet profiles, we have modelled droplets that separate from the substrate on which they sit.
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Smith, Edward. "On the coupling of molecular dynamics to continuum computational fluid dynamics". Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/15610.
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Molecular dynamics (MD) is a discrete modelling technique that is used to capture the nanoscale motion of molecules. MD can be used to accurately simulate a range of physical problems where the continuum assumption breaks down. Examples include surface interaction, complex molecules, local phase changes, shock waves or the contact line between fluids. However, beyond very small systems and timescales (μm and msec), MD is prohibitively expensive. Continuum computational fluid dynamics (CFD), on the other hand, is easily capable of simulating scales of engineering interest, (m and s). However, CFD is unable to capture micro-scale effects vital for many modern engineering fields, such as nanofluidics, tribology, nano-electronics and integrated circuit development. This work details the development of a set of techniques that combine the advantages of both continuum and molecular modelling methodologies, allowing the study of cases beyond the range of either technique alone. The present work is split into both computational and theoretical developments. The computational aspect involves the development of a new high-performance MD code, as well as a coupler (CPL) library to link it to a continuum solver. The MD code is fully verified, has similar performance to existing MD software and allows simulation of a wide range of cases. The CPL library is a robust, flexible and language independent API and the source code has been made freely available under the GNU GPL v3 license. Both MD and CPL codes are developed to allow very large scale simulation on high performance computing (HPC) facilities. The theoretical aspect includes the development of a rigorous mathematical framework and its application to develop novel coupling methodologies. The mathematical framework allows a discrete molecular system to be expressed in terms of the control volume (CV) formulation from continuum fluid dynamics. A discrete form of Reynolds’ transport theorem, is thus obtained, allowing both molecular and continuum systems to be expressed in a consistent manner. This results in a number of important insights into the molecular definition of stress. This CV framework allows mathematical operations to be localised to a control volume in space. It is ideally suited to apply coupling constraints to a region in space. To link the CFD and MD solvers in a rigorous and physically consistent manner, the CV framework is combined with the variational principles of classical mechanics. The result is a unification of a number of existing forms used in the coupling literature and a rigorous derivation of a new and more general coupling scheme.
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Harries, Alun M. "Investigating viscous fluid flow in an internal mixer using computational fluid dynamics". Thesis, Aston University, 2000. http://publications.aston.ac.uk/13261/.
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This thesis presents an effective methodology for the generation of a simulation which can be used to increase the understanding of viscous fluid processing equipment and aid in their development, design and optimisation. The Hampden RAPRA Torque Rheometer internal batch twin rotor mixer has been simulated with a view to establishing model accuracies, limitations, practicalities and uses. As this research progressed, via the analyses several 'snap-shot' analysis of several rotor configurations using the commercial code Polyflow, it was evident that the model was of some worth and its predictions are in good agreement with the validation experiments, however, several major restrictions were identified. These included poor element form, high man-hour requirements for the construction of each geometry and the absence of the transient term in these models. All, or at least some, of these limitations apply to the numerous attempts to model internal mixes by other researchers and it was clear that there was no generally accepted methodology to provide a practical three-dimensional model which has been adequately validated. This research, unlike others, presents a full complex three-dimensional, transient, non-isothermal, generalised non-Newtonian simulation with wall slip which overcomes these limitations using unmatched ridding and sliding mesh technology adapted from CFX codes. This method yields good element form and, since only one geometry has to be constructed to represent the entire rotor cycle, is extremely beneficial for detailed flow field analysis when used in conjunction with user defined programmes and automatic geometry parameterisation (AGP), and improves accuracy for investigating equipment design and operation conditions. Model validation has been identified as an area which has been neglected by other researchers in this field, especially for time dependent geometries, and has been rigorously pursued in terms of qualitative and quantitative velocity vector analysis of the isothermal, full fill mixing of generalised non-Newtonian fluids, as well as torque comparison, with a relatively high degree of success. This indicates that CFD models of this type can be accurate and perhaps have not been validated to this extent previously because of the inherent difficulties arising from most real processes.
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Dodds, David Scott. "Computational fluid dynamics (CFD) modelling of dilute particulate flows". Swinburne Research Bank, 2008. http://hdl.handle.net/1959.3/44947.
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Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, 2008.A thesis submitted for the degree of Doctor of Philosophy, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2008. Typescript. Bibliography: p. 129-142. Includes bibliographical references (p. 259-274)
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Williams, Nathan A. "Drag optimization of light trucks using computational fluid dynamics". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FWilliams%5FNathan.pdf.
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Thesis (M.S. in Mechanical Engineering and M.S. in Information Technology Management)--Naval Postgraduate School, September 2003.Thesis advisor(s): Joshua H. Gordis, Dan Boger. Includes bibliographical references (p. 157-158). Also available online.
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Shelley, Jonathan Knighton. "Incorporating Computational Fluid Dynamics Into The Preliminary Design Cycle". Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd979.pdf.
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Charmchi, Isar. "Computational Fluid Dynamics (CFD) Modeling of a Continuous Crystallizer". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Crystallization is one of the most important separation and purification processes in chemical and especially in pharmaceutical industries. Currently most crystallization processes in the industry are based on batch crystallization; however, due to the variation of product quality per batch, efforts
are made to move to continuous processes instead. In this
respect, micro and meso scale reactors represents a promising technology due to enhanced heat and mass transfer rates, which, translated to particle generation,
provide control of size, morphology, and composition. In this
study, a meso-scale continuous crystallizer has been characterized and optimized.
A stirred tubular continuous-crystallizer has been characterized and optimized
in which the crystallization of active pharmaceutical ingredients (APIs) can
be performed under controlled conditions. The crystallizer is formed by two tubes,
one for nucleation and the other one for growth, in order to separate different phenomena
to control better the process and hence the crystal size distribution. The
optimized nucleation tube has a length of 35 cm and a diameter of 3 cm with a
long axial blade across the tube with the length of 30 cm and 2.5 cm of diameter.
The phenomena of mixing helps to achieve homogeneous supersaturation along the
tube to prevent growth during the nucleation and enables narrow residence time
distribution of the crystals in the tube with the help of gravity to achieve narrower
crystal size distribution.
Computational
fluid dynamics (CFD) is used to optimize the process. CFD is the
application of numerical methods to solve systems of partial differential equations
related to
fluid dynamics. The continuity and the momentum equations are the
most commonly applied equations within CFD, and together they can be used to
calculate the velocity and pressure distributions in a
fluid.
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Borrell, Pol Ricard. "Parallel algorithms for computational fluid dynamics on unstructured meshes". Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/124702.
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La simulació numèrica directa (DNS) de fluxos complexes és actualment una utopia per la majoria d'aplicacions industrials ja que els requeriments computacionals son massa elevats. Donat un flux, la diferència entre els recursos computacionals necessaris i els disponibles és cobreix mitjançant la modelització/simplificació d'alguns termes de les equacions originals que regeixen el seu comportament. El creixement continuat dels recursos computacionals disponibles, principalment en forma de super-ordinadors, contribueix a reduir la part del flux que és necessari aproximar. De totes maneres, obtenir la eficiència esperada dels nous super-ordinadors no és una tasca senzilla i, per aquest motiu, part de la recerca en el camp de la Mecànica de Fluids Computacional es centra en aquest objectiu. En aquest sentit, algunes contribucions s'han presentat en el marc d'aquesta tesis.
El primer objectiu va ser el desenvolupament d'un codi de CFD de propòsit general i paral·lel, basat en la metodologia de volums finits en malles no estructurades, per resoldre problemes de multi-física. Aquest codi, anomenat TermoFluids (TF), té un disseny orientat a objectes i pensat per ser usat de forma altament eficient en els super-ordinadors actuals. Amb el temps, ha esdevingut pel grup una eina fonamental en projectes tant de recerca bàsica com d'interès industrial.
En el context d'aquesta tesis, el treball s'ha focalitzat en el desenvolupament de dos de les llibreries més bàsiques de TermoFluids: i) La Basics Objects Library (BOL), que es una plataforma de software sobre la qual estan programades la resta de llibreries del codi, i que conté els mètodes algebraics i geomètrics fonamentals per la implementació paral·lela dels algoritmes de discretització, ii) la Linear Solvers Library (LSL), que conté un gran nombre de mètodes per resoldre els sistemes d'equacions lineals derivats de les discretitzacions.
El primer capítol d'aquesta tesi conté les principals idees subjacents al disseny i la implementació de la BOL i la LSL, juntament amb alguns exemples i algunes aplicacions industrials. En els capítols posteriors hi ha una explicació detallada de solvers específics per algunes aplicacions concretes.
En el segon capítol, es presenta un solver paral·lel i directe per la resolució de l'equació de Poisson per casos en els quals una de les direccions del domini té condicions d'homogeneïtat. En la simulació de fluxos incompressibles, l'equació de Poisson es resol almenys una vegada en cada pas de temps, convertint-se en una de les parts més costoses i difícils de paral·lelitzar del codi. El mètode que proposem és una combinació d'una descomposició directa de Schur (DDS) i una diagonalització de Fourier. La darrera descompon el sistema original en un conjunt de sub-sistemes 2D independents que es resolen mitjançant l'algorisme DDS. Atès que no s'imposen restriccions a les direccions no periòdiques del domini, aquest mètode és aplicable a la resolució de problemes discretitzats mitjançat l'extrusió de malles 2D no estructurades. L'escalabilitat d'aquest mètode ha estat provada amb èxit amb un màxim de 8192 CPU per malles de fins a ~10⁹ volums de control.
En el darrer capitol capítol, es presenta un mètode de resolució per l'equació de Transport de Boltzmann (BTE). La estratègia emprada es basa en el mètode d'Ordenades Discretes i pot ser aplicat en discretitzacions no estructurades. El flux per a cada ordenada angular es resol amb un mètode de substitució equivalent a la resolució d'un sistema lineal triangular. La naturalesa seqüencial d'aquest procés fa de la paral·lelització de l'algoritme el principal repte. Diversos algorismes de substitució han estat analitzats, esdevenint una de les heurístiques proposades la millor opció en totes les situacions analitzades, amb excel·lents resultats. Els testos d'eficiència paral·lela s'han realitzat usant fins a 2560 CPU.Direct Numerical Simulation (DNS) of complex flows is currently an utopia for most of industrial applications because computational requirements are too high. For a given flow, the gap between the required and the available computing resources is covered by modeling/simplifying of some terms of the original equations. On the other hand, the continuous growth of the computing power of modern supercomputers contributes to reduce this gap, reducing hence the unresolved physics that need to be attempted with approximated models. This growth, widely relies on parallel computing technologies. However, getting the expected performance from new complex computing systems is becoming more and more difficult, and therefore part of the CFD research is focused on this goal. Regarding to it, some contributions are presented in this thesis. The first objective was to contribute to the development of a general purpose multi-physics CFD code. referred to as TermoFluids (TF). TF is programmed following the object oriented paradigm and designed to run in modern parallel computing systems. It is also intensively involved in many different projects ranging from basic research to industry applications. Besides, one of the strengths of TF is its good parallel performance demonstrated in several supercomputers. In the context of this thesis, the work was focused on the development of two of the most basic libraries that compose TF: I) the Basic Objects Library (BOL), which is a parallel unstructured CFD application programming interface, on the top of which the rest of libraries that compose TF are written, ii) the Linear Solvers Library (LSL) containing many different algorithms to solve the linear systems arising from the discretization of the equations. The first chapter of this thesis contains the main ideas underlying the design and the implementation of the BOL and LSL libraries, together with some examples and some industrial applications. A detailed description of some application-specific linear solvers included in the LSL is carried out in the following chapters. In the second chapter, a parallel direct Poisson solver restricted to problems with one uniform periodic direction is presented. The Poisson equation is solved, at least, once per time-step when modeling incompressible flows, becoming one of the most time consuming and difficult to parallelize parts of the code. The solver here proposed is a combination of a direct Schur-complement based decomposition (DSD) and a Fourier diagonalization. The latter decomposes the original system into a set of mutually independent 2D sub-systems which are solved by means of the DSD algorithm. Since no restrictions are imposed in the non-periodic directions, the overall algorithm is well-suited for solving problems discretized on extruded 2D unstructured meshes. The scalability of the solver has been successfully tested using up to 8192 CPU cores for meshes with up to 10 9 grid points. In the last chapter, a solver for the Boltzmann Transport Equation (BTE) is presented. It can be used to solve radiation phenomena interacting with flows. The solver is based on the Discrete Ordinates Method and can be applied to unstructured discretizations. The flux for each angular ordinate is swept across the computational grid, within a source iteration loop that accounts for the coupling between the different ordinates. The sequential nature of the sweep process makes the parallelization of the overall algorithm the most challenging aspect. Several parallel sweep algorithms, which represent different options of interleaving communications and calculations, are analyzed. One of the heuristics proposed consistently stands out as the best option in all the situations analyzed. With this algorithm, good scalability results have been achieved regarding both weak and strong speedup tests with up to 2560 CPUs.
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Houzeaux, G. (Guillaume). "A Geometrical Domain Decomposition Methods in Computational Fluid Dynamics". Doctoral thesis, Universitat Politècnica de Catalunya, 2002. http://hdl.handle.net/10803/6858.
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El método de descomposición de dominios (DD) que se propone en esta tesis pretende resolver flujos incompresibles alrededor de objetos en movimiento relativo. El algoritmo de DD está basado en un acoplamiento del tipo Dirichlet/Neumann(Robin) aplicado a subdominios con solapamiento, y es, por tanto, una extensión del método Dirichlet/Neumann(Robin) clásico con subdominios disjuntos. En realidad, el campo de aplicación de este estudio es mucho más amplio puesto que en el se propone un posible marco teórico para abordar la extensión a subdominios solapados de los métodos mixtos clásicos: métodos Dirichlet/Robin, Dirichlet/Neumann, Robin/Neumann y Robin/Robin. Se observa que los métodos mixtos propuestos heredan propiedades del método de Schwarz y al mismo tiempo conservan el comportamiento de sus equivalentes sin solapamiento cuando este tiende a cero. Se muestra como resultado principal que el solapamiento hace estos métodos más robustos que los métodos sin solapamiento. El método de DD que se estudia es geométrico y algorítmico. Es geométrico en el sentido de que la partición del dominio computacional se lleva a cabo antes del proceso de mallado y de acuerdo con el acoplamiento de DD que se prevé usar.
Es también algorítmico porque la solución en cada subdominio se obtiene en procesos diferentes y el intercambio de información entre subdominios se realiza mediante un código maestro. Tal estrategia es muy flexible puesto que requiere muy pocas modificaciones del código numérico original. Por consiguiente, sólo el código maestro necesita ser adaptado a los códigos y estrategias numéricos utilizados en cada subdominio.
Se presenta una descripción detallada de la implementación del método de DD propuesto en el contexto numérico de los elementos finitos. Presentamos técnicas de interpolación para los datos de tipo Dirichlet y Neumann y desarrollamos algoritmos de conservación. Una vez el acoplamiento de DD y las interpolaciones definidos, presentamos un método del tipo Chimera para la resolución de flujos alrededor de objetos en movimiento. En particular, definimos transformaciones tensoriales para transformar variables de un subdominio a otro.
Finalmente, el algoritmo de DD se aplica a un código implícito para la resolución de las ecuaciones de Navier-Stokes incompresibles y también a las ecuaciones de Navier-Stokes promediadas con un modelo de turbulencia de una ecuación.
The domain decomposition (DD) method we present in this work aims at solving incompressible flows around objects in relative motion. The DD algorithm is based on a Dirichlet/Neumann(Robin) coupling applied to overlapping subdomains. Hence, it is an extension of the classical Dirichlet/Neumann(Robin) method which uses disjoint subdomains.
Actually, the field of application of this work is wider as it proposes to set up a possible theoretical framework for studying the overlapping extensions of classical mixed methods: the Dirichlet/Robin, Dirichlet/Neumann, Robin/Neumann and Robin/Robin DD methods.
We observe that mixed DD methods inherit some properties of the Schwarz method while they keep the behavior of the classical mixed DD methods when the overlap tends to zero.
As a main result, we show that the overlap makes the proposed methods more robust than disjoint mixed DD methods.
The DD method we propose is geometric and algorithmic. It is geometric because the partition of the computational domain is performed before the meshing, and in accordance to the DD coupling. It is also algorithmic because the solution on each subdomain is obtained on separate processes and the exchange of information between the subdomains is carried out by a Master code. This strategy is very flexible as it requires almost no modification to the original numerical code. Therefore, only the Master code has to be adapted to the numerical codes and strategies used on each subdomain.
We present a detailed description of the implementation of the DD methods in the numerical framework of finite elements. We present interpolation techniques for Dirichlet and Neumann data as well as conservation algorithms.
Once the domain decomposition coupling and interpolation techniques are defined, we set up a Chimera method for the solution of the flow over objets in relative movements. Tensorial transformations are introduced to be able to express variables measures in one subdomain.
Finally, the DD algorithm is applied to an implicit finite element code for the solution of the Navier-Stokes equations and also of the Reynolds Averaged Navier-Stokes equations together with a one-equation turbulence model.
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Williams, Adam N. "Computational fluid dynamics analysis of a dual mode thruster". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA370896.
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Thesis (M.S. in Astronautical Engineering) Naval Postgraduate School, September 1999."September 1999". Thesis advisor(s): Garth V. Hobson. Includes bibliographical references (p. 135-136). Also Available online.
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Kaggerud, Torbjørn Herder. "Modeling an EDC Cracker using Computational Fluid Dynamics (CFD)". Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9536.
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The process used by the Norwegian company Hydro for making Vinyl Chloride Monomer (VCM) from natural gas and sodium chloride has been studied. A three dimensional CFD model representing the firebox of the EDC cracker has been developed using the commercial CFD tool Fluent. Heat to the cracker is delivered by means of combustion of a fuel gas consisting of methane and hydrogen. In the developed CFD model used in this work, the combustion reaction itself is omitted, and heat is delivered by hot flue gas. With the combustion reaction left out, the only means of tuning the CFD model is through the flue gas inlet temperature. With the flue gas inlet temperature near the adiabatic flame temperature, the general temperature level of the EDC cracker was reported to be too high. The outer surface temperature of the coil was reported to be 3-400 K higher than what was expected. By increasing the mass flow of flue gas and decreasing the temperature, the net delivered heat to the firebox was maintained at the same level as the first case, but the temperature on the coil was reduced by 100-150 K. Further reductions in the flue gas inlet temperature and modifications in the mass flow of flue gas at the different burner rows, eventually gave temperature distributions along the reaction coil, and flue gas and refractory temperatures, that resemble those in the actual cracker. The one-dimensional reactor model for the cracking reaction represents the actual cracker in a satsifactorily manner. The cracking reaction was simulated using a simple, global reaction mechanism, thus only the main components of the process fluid, EDC, VCM and HCl, can be studied. The model is written in a way suitable for implementation of more detailed chemical reaction mechanisms. The largest deviation in temperature between measured and simulated data are about 5%. At the outlet the temperature of the process fluid is equal to the measured data. The conversion of EDC out of the firebox is assumed to be 50 wt-%, this value is met exactly by the model.
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Al-Far, Salam H. "Indirect fired oven simulation using computational fluid dynamics (CFD)". Thesis, London South Bank University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618655.
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