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1
Myre, David D. "Model fan passage flow simulation". Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23962.
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Enge, Leo y Felix Liu. "Crowd Simulation Using Flow Tiles". Thesis, KTH, Skolan för teknikvetenskap (SCI), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231025.
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Crowd simulations are being used in an increasing number of different applications, like evacuation scenarios, video games and movie special effects This creates a demand for crowd simulators that are simple to use and accessible to users of varying backgrounds. We will study the flow tile method proposed by Chenney [1], which provides an intuitive way of interactively designing divergence free velocity fields for various applications. A reimplementation of Chenney's method will be given and the implementation will be evaluated in terms of user-friendliness and how well the use of static spatially defined velocity fields suits crowd simulation. Furthermore the possibility of using the velocity fields for other related applications such as mobile robotics will be touched on as well.Simuleringar av folkmassor används i ett ökande antal olika tillämpningar, som evakueringsscenarion, datorspel och specialeffekter för film. Detta skapar en efterfrågan efter simulatorer som är enkla att använda och tillgängliga för användare från olika ämnesområden och bakgrunder. Vi kommer att studera flow tile-metoden som Chenney [1] föreslår. Metoden är ett intuitivt och interaktivt sätt att skapa divergensfria hastighetsfält för olika tillämpningar. En omimplementation av Chenneys metod kommer att ges och implementationen kommer att evalueras i termer av användarvänlighet och hur väl användningen av hastighetsfält som är statiska och definierade i rummet passar för simulering av folkmassor. Vidare kommer möjligheten att använda hastighetsfälten för andra liknande tillämpningar, som robotik, att diskuteras också.
3
Ahmad, Reza Amini. "Produktutveckling skorstensfläkt i Flow Simulation". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80573.
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Reasor, Daniel Archer. "Numerical simulation of cellular blood flow". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42760.
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In order to simulate cellular blood, a coarse-grained spectrin-link (SL) red blood cell (RBC) membrane model is coupled with a lattice-Boltzmann (LB) based suspension solver. The LB method resolves the hydrodynamics governed by the Navier--Stokes equations while the SL method accurately models the deformation of RBCs under numerous configurations. This method has been parallelized using Message Passing Interface (MPI) protocols for the simulation of dense suspensions of RBCs characteristic of whole blood on world-class computing resources.
Simulations were performed to study rheological effects in unbounded shear using the Lees-Edwards boundary condition with good agreement with rotational viscometer results from literature. The particle-phase normal-stress tensor was analyzed and demonstrated a change in sign of the particle-phase pressure from low to high shear rates due to RBCs transitioning from a compressive state to a tensile state in the flow direction. Non-Newtonian effects such as viscosity shear thinning were observed for shear rates ranging from 14-440 inverse seconds as well as the strong dependence on hematocrit at low shear rates. An increase in membrane bending energy was shown to be an important factor for determining the average orientation of RBCs, which ultimately affects the suspension viscosity. The shear stress on platelets was observed to be higher than the average shear stress in blood, which emphasizes the importance of modeling platelets as finite particles.
Hagen-Poiseuille flow simulations were performed in rigid vessels for investigating the change in cell-depleted layer thickness with shear rate, the Fåhraeus-Linqvist effect, and the process of platelet margination. The process of platelet margination was shown to be sensitive to platelet shape. Specifically, it is shown that lower aspect ratio particles migrate more rapidly than thin disks. Margination rate is shown to increase with hematocrit, due to the larger number of RBC-platelet interactions, and with the increase in suspending fluid viscosity.
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Swarbrick, Sean James. "Finite element simulation of viscoelastic flow". Thesis, Teesside University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278423.
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Christian, Andrew D. (Andrew Dean). "Simulation of information flow in design". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11102.
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Zhu, Lailai. "Simulation of individual cells in flow". Doctoral thesis, KTH, Stabilitet, Transition, Kontroll, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-142557.
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In this thesis, simulations are performed to study the motion ofindividual cells in flow, focusing on the hydrodynamics of actively swimming cells likethe self-propelling microorganisms, and of passively advected objects like the red bloodcells. In particular, we develop numerical tools to address the locomotion ofmicroswimmers in viscoelastic fluids and complex geometries, as well as the motion ofdeformable capsules in micro-fluidic flows. For the active movement, the squirmer is used as our model microswimmer. The finiteelement method is employed to study the influence of the viscoelasticity of fluid on theperformance of locomotion. A boundary element method is implemented to study swimmingcells inside a tube. For the passive counterpart, the deformable capsule is chosen as the modelcell. An accelerated boundary integral method code is developed to solve thefluid-structure interaction, and a global spectral method is incorporated to handle theevolving cell surface and its corresponding membrane dynamics. We study the locomotion of a neutral squirmer with anemphasis on the change of swimming kinematics, energetics, and flowdisturbance from Newtonian to viscoelastic fluid. We also examine the dynamics of differentswimming gaits resulting in different patterns of polymer deformation, as well as theirinfluence on the swimming performance. We correlate the change of swimming speed withthe extensional viscosity and that of power consumption with the phase delay of viscoelasticfluids. Moreover, we utilise the boundary element method to simulate the swimming cells in astraight and torus-like bent tube, where the tube radius is a few times the cell radius. Weinvestigate the effect of tube confinement to the swimming speed and power consumption. Weanalyse the motions of squirmers with different gaits, which significantly affect thestability of the motion. Helical trajectories are produced for a neutralsquirmer swimming, in qualitative agreement with experimental observations, which can beexplained by hydrodynamic interactions alone. We perform simulations of a deformable capsule in micro-fluidic flows. We look atthe trajectory and deformation of a capsule through a channel/duct with a corner. Thevelocity of capsule displays an overshoot as passing around the corner, indicating apparentviscoelasticity induced by the interaction between the deformable membrane and viscousflow. A curved corner is found to deform the capsule less than the straight one. In addition, we propose a new cell sorting device based on the deformability of cells. Weintroduce carefully-designed geometric features into the flow to excite thehydrodynamic interactions between the cell and device. This interaction varies andclosely depends on the cell deformability, the resultant difference scatters the cellsonto different trajectories. Our high-fidelity computations show that the new strategy achievesa clear and robust separation of cells. We finally investigate the motion of capsule in awall-bounded oscillating shear flow, to understand the effect of physiological pulsation to thedeformation and lateral migration of cells. We observe the lateral migration velocity of a cellvaries non-monotonically with its deformability.QC 20140313
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Li, Yiguang. "Three-Dimensional Flow and Performance Simulation of Multistage Axial Flow Compressors". Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/4591.
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\Yith the current develop111ent in computer technology and Computational
Fluid D)"n<'tlllics techniques, t.he si11utlation within axial flow compressors becomes
1110re and 1110re pract.ical and beneficial to the compressor designs. Due to the
insufficient capabilit)" of today's COll1put.ers for three-dimensional unsteady flow
1110delling of 111Ult i~Llg(' axial flow compressors, sophisticated models of steady
state flow and perfor111ance 1110delling of the C0111prcssors deserve to be thoroughly
investigated.
In l1utltistage C0111pressor sinlulations with steady state methods, frame of reference
is fixed on blades and the c0111putational domains for rotors and stators
haye relati\"e rotation. One of the difficulties in such simulations is how to pass
information across the interfaces between blade rows without losing continuity.
Two 111ajor stead)" state modelling approaches, a mixing plane approach based
on Denton's circu111ferentially non-uniform mixing plane model and a deterministic
stress approach based on Adamczyk's average passage model, are investigated
and compared with each other through the flow predictions of the third stage of
Cranfield Low Speed Research Compressor at peak efficiency operating condition.
In the deterministic stress approach, overlapped solution domains are introduced
to calculate deterministic stresses in order to "close" the time-averaged
governing equation system and the influence of the downstream blade row of the
blade row under investigation has to be imposed through the simulation of bodyforce
and blade blockage effect of the downstream blade row. An effective method
of simulating bodyforce and blade blockage effect has been developed and proven
to be simple in programming.
ConYentionally, boundary conditions are specified in CFD calculations based
on experimental data or other empirical calculations. By taking advantage of the
special flow features in rear stages of multistage axial flow compressors where each
rear stage behaves like a repeating stage of its neighbouring stages in terms of
flow pattern at the inlet and the exit of these stages, a repeating stage model has
been developed aiming at significantly simplifying the boundary conditions when
simulating rear stages of a multistage axial flow compressor with only mass flow
rate and stage exit average static pressure required as global input.
A computer simulation system 1'/ STurbo3D has been developed to investigate
a11d assess different steady state simulation models within multistage compressor
environment. It has been proven that with the mixing plane model M STurbo3D is
able to predict flows in multistage low speed axial flow compressors with acceptable
accuracy. Application of the repeating stage model to the third stage of LS RC
shows that the prediction with this model has equivalent accuracy to the prediction
with the conventional boundary setting, and proves that the repeating stage
model is an effective alternative to the expensive complete compressor simulation.
The deterministic stress model provides more information of rotor-stator interaction
and slightly better performance prediction than the mixing plane model, but
the benefits of the model is not significant when applied to low speed axial flow
compressors.
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ABRUNHOSA, JOSE DINIZ MESQUITA. "TURBULENT COMPLEX FLOW SIMULATION WITH CLASSICAL MODELING AND LARGE EDDY SIMULATION". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4346@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOUma investigação da capacidade de previsão de modelos de turbulência baseados na modelagem estatística clássica e de grandes escalas é apresentada. A modelagem estatística clássica de turbulência (média de Reynolds) foi analisada, através da solução de escoamentos complexos, como, por exemplo, o escoamento turbulento em degrau (backstep). Especial atenção foi dada aos modelos kapa-epsilon de baixo Reynolds e as variantes renormalizadas (RNG). O comportamento dos vários termos da equação da energia cinética turbulenta na região da parede foram analisados em detalhes, especialmente o termo de difusão de pressão. Avaliou-se a importância da correta modelagem do termo de difusão de pressão sobre as predições dos modelos de baixo número de Reynolds, nas regiões de recirculação. Alguns modelos, propostos na literatura para o termo de difusão de pressão, foram também avaliados teórica e numericamente. A capacidade de previsão da metodologia de simulação de grandes escalas (LES por Large Eddy Simulation) também foi realizada. O desempenho do modelo de Smagorinsky para prever escoamentos limitados por fronteiras sólidas foi avaliado do ponto de vista computacional. Utilizou-se o método de volumes finitos para integrar tanto as equações médias de Reynolds quanto as equações LES. O escoamento turbulento em canal foi resolvido de modo bidimensional e tridimensional. Já o escoamento em degrau (backstep) foi resolvido exclusivamente de modo bidimensional, enquanto o escoamento em um duto de seção quadrada foi simulado de modo tridimensional. Os resultados foram comparados com aqueles obtidos pelos modelos de baixo Reynolds, analisando-se a relação custo-benefício.
An investigation of turbulence models prediction capacity based on classical statistical modeling and large eddy simulation (LES) is presented. The classical statistical modeling (average of Reynolds) was analyzed, by investigating the solution of complex flows, as, for example, the turbulent flow past a backwardfacing- step (backstep). Special attention was given to low Reynolds number k-e models and models derived by renormalization group theory (RNG). The behavior of the different terms in the turbulent kinetic energy equation in the near wall region was examined in details, specially the pressure diffusion term. It was evaluated the importance of the correct modeling of the pressure diffusion term on the predictions of the low Reynolds number models, in recirculating flows. A few models, proposed in the literature for the pressure diffusion term, were also evaluated theoretically and numerically. The prediction capacity of large eddy simulation (LES) technique was also investigated. The ability of Smagorinsky model to predict complex limited wall flows was analyzed from a computational standpoint. The finite-volume method was employed to integrate both the Reynolds average and LES equations. The fully developed turbulent channel flow was solved in two- dimensional and three-dimensional numerical simulations. The turbulent flow over a backward-facing-step was computed exclusively in a twodimensional manner, while the fully developed turbulent flow in a straight square duct was simulated in a three-dimensional manner. The results were compared with those obtained by the low Reynolds models, analyzing the cost-benefit relation.
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Wang, Roy J. "Simulation based evaluation on the effects of jaywalking". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 77 p, 2009. http://proquest.umi.com/pqdweb?did=1885755931&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Farooq, Muhammad Asif. "Cartesian Grid Method for Compressible Flow Simulation". Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16538.
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The Cartesian grid method is an alternative to the existing methods to solve a physical problem governed by partial differential equations (PDEs) computationally. Researchers are interested in this method due to its simplicity of grid generation, less computational effort and ease of implementation into a computer code. One of the other options to solve a physical PDE problem is by the body-fitted grid method. In the body-fitted grid method, the boundary points are grid points. This is not the case with the Cartesian grid method where the body wall is embedded as a boundary into a Cartesian grid resultingin irregular cells near the embedded boundary. These irregular cells near the embedded boundary are known as cut-cells. Instead of using special treatmentsof the cut-cells or enforcing the presence of the embedded boundary by adding source terms at the Cartesian grid points near the boundary, the kinematic and other boundary conditions can be introduced in the Cartesian grid method via ghost points. Those grid points which lie inside the embedded boundary and are also a part of computation are called ghost points. Inactive grid points inside the embedded boundary are referred to as solid points. In the present Cartesian grid method, based on a ghost point treatment, local symmetry conditions are imposed at the embedded wall boundary. The ghost point treatments available in the literature are difficult to implement due to complex procedures. We are introducing a new approach to approximate the kinematics of the embedded boundary by a very simple ghost point treatment called the simplified ghost point treatment. In this approach, we consider the grid lines in the x- and y- directions as approximations of the lines normal to the embedded boundary depending on whether the angle between the normal and the x- or y-directions is closer. For 1D hyperbolic nonlinear systems of conservation laws, we use the moving normal shock wave as a test case for the 1D compressible Euler equations.For the 2D compressible Euler equations, we test the simplified ghost point treatment for an oblique shock wave generated by a wedge. Then, we verified our approach for slender bodies, namely for supersonic flow over a circular arc airfoil and for transonic flow over a circular arc bump in a channel. In a final problem, we applied the simplified ghost point treatment to blunt body flow and considered supersonic flows over a cylinder using the 2D compressible Euler and Navier-Stokes equations. The results are good or comparable to those found in the existing literature.
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Solomon, Luiza. "Learning and flow control in optimistic simulation". Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29475.
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This thesis has two main contributions. The first contribution is the development of a modular, easy-to-use Time Warp simulation engine targeted towards distributed-memory environments. The second contribution is the analysis and experimental verification of the performance of the flow control algorithm proposed by Choe in a distributed-memory environment.The Time Warp simulation engine TWSIM provides our laboratory with a research medium for Time Warp simulations in a distributed-memory environment such as a network of workstations. The modular design of TWSIM allows for easy integration of any new simulation application and for fast testing of optimizations and improvements to the Time Warp mechanism. Its compact size and object-oriented implementation using the C++ programming language result in a short learning curve for future users and developers.
The flow control algorithm proposed by Choe was implemented and analyzed with the aid of the TWSIM simulation engine. The algorithm makes use of stochastic learning automata to balance simulations loads by continuously regulating the flow of events between processors during the course of the simulation. Three different load metrics are considered: memory usage, virtual time, and a space-time product of the first two metrics. The algorithm was tested with two different simulation applications: a queuing network simulation and a Personal Communication Services (PCS) simulation. Results show that the flow control algorithm reduces the memory usage; the number of rollbacks and the number of antievents at the expense of the simulation time. As well, it becomes apparent that the behaviour of the flow control algorithm is not a consequence of learning.
Finally, we discuss a number of approaches to learning and flow control using the outlines of the flow control algorithm, and we consider the extent of the performance improvement to be expected from memory-based schemes for limiting Time Warp optimism in a distributed-memory environment.
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Carnevali, Emanuele. "Simulation of a viscoelastic Taylor-Couette flow". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Since the early stages of Computational Rheology the Taylor-Couette geometry received a lot of attention from researchers, up to becoming one of the benchmark problem of viscoleastic flows. In particular, the circular bounding geometry, together with the shear driven characteristic, allowed to gain relevant insight about the relation between the distortion of polymer conformation, and the arise of elastic instabilities.
The present document has the purpose of presenting the thesis project results, concerning the numerical investigation of a Taylor-Couette geometry through the newly developed viscoelastic toolbox Rheotool of OpenFOAM.
The simulations have been performed for increasing values of Weissemberg number, with the aim of detecting the effect of polymer stretching on the arise and development of particular fluid dynamic structures; furthermore, to understand the effect of space refinement on motion evolution, three different meshes have been used, exploiting also a new available stabilization technique based on stress-velocity coupling to avoid numerical breakdown.
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Gobert, Christian. "Large Eddy Simulation of particle-laden flow". kostenfrei, 2010. https://mediatum2.ub.tum.de/node?id=829484.
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Ou, Zhiliang. "Numerical simulation of flow around vertical cylinders". University of Western Australia. School of Civil and Resource Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0185.
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Local scour around bridge piers can cause serious damages and structural failure to the bridge. Correct prediction of the scour is an important criterion for the engineering design. Though the subject has been investigated for many decades, the theoretical developments have been very limited due to the complicated interaction of three-dimensional flow and the sediment transport. This thesis concerns the flow around a vertical bottom mounted cylinder exposed to currents and is considered as the initial phase of a study towards modeling local scour around vertical bottom-mounted structures. The aim of the present study is to obtain a better understanding of the complex three-dimensional flow and the mechanisms related to the scouring. The study started with the development of a three-dimensional numerical model to simulate flow around cylindrical structures. After validation of the model, the model was applied to investigate flow around an isolated rectangular cylinder. Unsteady flows around cylinders of a square cross section (A/D = 1) and a rectangular cross section (A/D = 2) were simulated to understand the flow properties around a cylinder other than a circular cross section. Three-dimensional flow patterns, pressure distribution, forces on the cylinder and vortex-shedding frequencies were discussed. It was found that the present numerical results generally agree well with the experimental data. Flow around a vertical cylinder mounted on a rigid bed was then investigated by the numerical model. A circular and a square cross sections were considered respectively. Flow structures of horseshoe vortex and the wake vortex which are the major mechanisms leading to the scouring around the base of the vertical cylinder were explored. The bed shear stress distributions that directly affect the scour processes were discussed. Finally the numerical model was applied to study the flow around a submerged square cylinder mounted on a bed, which has significant engineering relevance to the local scour around structures, such as bridge pier foundation itself, or a caisson placed underwater around the pier bottom for scour protection. The numerical calculations were carried out at different cylinder heights to investigate the effect of the cylinder height on the flow properties. It was found that for submerged cylinders with the height of less than one and a half of the cylinder side width the maximum bed shear stress amplification is about 60% of the value of an infinite long cylinder. The quantification of the shear stress reduction is important for scour protection design.
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Suicmez, Vural Sander. "Pore scale simulation of three-phase flow". Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441972.
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Stallard, Timothy J. "Simulation of unsteady viscous flow-structure interaction". Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418130.
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The design of slender structures such as longspan bridges, masts, offshore risers and cables is strongly influenced by their response behaviour when subjected to unsteady loads due to wind, waves and current. Simulation of the behaviour of a viscous flow past a structural cross section is of great importance to engineers concerned with the design of such structures. Offshore engineers are concerned with estimating the magnitude of structural forces induced by the most severe storm-induced wave events. Numerous studies have been conducted in an effort to estimate the structural forces induced by both regular and irregular waves. However, estimation of the maximum extreme wave-induced structural forces, particularly for relatively small diameter horizontal components, has received less attention. Since the most widely used method for estimating the force experienced by a bluff body subjected to wave loading is the empirical drag-inertia equation developed by Morison, O’ Brien, Johnson, and Schaaf (1950), it is important to determine whether this equation is adequate to describe the forces imposed by extremely large ocean waves. A method is presented for the simulation of incompressible viscous flow past acylinder using a stream function vorticity-transport formulation discretised on a cutcell quadtree mesh. A cut-cell technique is employed to provide accurate boundary representation and to facilitate the simulation of flow past a moving boundary. The finite volume discretisation consists of second-order accurate central difference approximations within uncut flow cells and a polynomial reconstruction technique within the cut-cells that are intersected by the solid boundary. Several preliminary validation tests concerned with flow past a circular cylinder are presented to confirm the accuracy of the numerical model. Firstly, the cut-cell discretisation is applied to the solution of the Euler equations and is shown to be almost second order accurate. Comparisons of wake geometry and force coefficients for steady and oscillatory flows at low Reynolds number are then made with existing results, and show satisfactory agreement. Preliminary tests are presented to assess the accuracy of a cut-cell based method for simulating flow past a circular body that moves across a background mesh. A series of experiments is also presented concerned with the measurement of theforce experienced by a circular cylinder undergoing a pre-defined two-dimensionalmotion within a still fluid. The cylinder trajectory is representative of the motionof a fluid particle beneath an idealised large ocean wave as defined by the NewWave formulation (Tromans et al. 1991). It is observed that, whilst the magnitude of high frequency vortex induced force fluctuations varies with the ratio of wave amplitude to cylinder diameter (A=D) and the wave spectrum shape, the overall shape of both x- and y-direction force time histories is very similar for all wave groups for which the underlying spectrum has the same shape. For all of the two-dimensional cylinder motions considered, the spectrum of both measured forces closely approximates the spectrum of uq (where u is a component of the velocity vector and q the absolute velocity) and, as a result, the vector form of the well known equation developed by Morison et al. (1950) is shown to provide a satisfactory estimate of the cartesian force components. The high frequency component of the force that is not captured by the Morison et al. equation is clearly identified as a lift-type force in the radial direction. For design purposes, a reasonable estimate of the magnitude of the peak force is obtained by neglecting inertial forces and employing a drag coefficient CD = 1.0.
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Clark, N. R. "Kinematic simulation of a turbulent channel flow". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597714.
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Kinematic simulation is a Lagrangian model of turbulence based on an underlying random Eulerian field. We detail a new method of generating kinematic simulation fields in a channel. We employ a new decomposition for kinematic simulation which ensures that the boundary conditions are automatically satisfied while preserving incompressibility. We impose statistics up to second order, including the Reynolds shear-stress and one-dimensional spectral densities. These fields are used as a Lagrangian model and the statistics of one particle, and particle pairs are calculated in a kinematic simulation of a fully developed stationary channel flow with a Reynolds number based on wall units, of 200. A dimensional analysis of the relative accelerations of particle pairs in the channel is presented. We argue that, in kinematic simulation, the relative acceleration correlation should be approximately stationary and that the variance should increase quadratically in time, for times much smaller than the Lagrangian integral time scales. This is used in an analysis of the second order moments of pair separation, and reltive velocity and compared to the simulation data. Finally we examine the flow structures present in the kinematic simulation fields, concentrating on the log region streak structures, and consider their effects upon the Lagrangian statistics.
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Sukirman, Y. "Petroleum reservoir simulation coupling flow and subsidence". Thesis, Swansea University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639129.
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A versatile numerical solution is presented for simulating a compacting oil reservoir and its subsidence at the surface. From a literature review, numerous studies related to this subject have been reported in various situations. Herein, a numerical model, based on the finite element method, was used for solving three dimensional, three immiscible and compressible fluids flowing in a deforming porous media. The mathematical formulation was derived based on Biot's self consistent theory which describes a fully coupled governing equation system for a saturated oil reservoir. It consists of the equilibrium and continuity equations for oil-, gas- and water-phases flowing in a porous media. The non-linearities due to mobility and accumulation terms were implicitly determined at each iteration level. In this thesis, these non-linear variables account for the effects of reservoir heterogeneity, relative permeability contrasts, rock and fluid compressibility factors, capillary pressure and other rock properties. An elastoplastic soil model, based on a Mohr Coulomb yield surface, was used for simulating the deformation behaviour of both reservoir and overburden/underburden formations. The Galerkin based finite element method was applied to obtain simultaneous solutions to the governing equation system where the displacement and the fluid pressures are the primary unknowns. The final discretized equations are solved by a direct solver using implicit procedures. A linear analysis was used to study the stability conditions of the present formulation and again showed that this implicit scheme is unconditionally stable. In the present simulation code, the convergence and mass balance checks are applied for monitoring an incremental numerical error within two different iteration calculations. Finally, several simulations were conducted in two different stages; firstly the validation and secondly an application of the present finite element code. A summary on future applications is also included.
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Gillespie, Jennifer L. "Modelling and computer simulation of patient flow". Thesis, Ulster University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.646847.
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The population of the United Kingdom is increasingly ageing and diseases, like cancer and stroke, are becoming more common in our society. This is having a detrimental affect on the performance of the National Health Service. Various schemes and services have been introduced to increase efficiency, and key performance indicators help to identify areas of best practice. By realistically modelling healthcare facilities with analytic and simulation models, based on queueing theory, we can provide detailed information to healthcare managers and clinicians. These models can help to identify issues and cost inefficiencies for early intervention. Analytic models are less data and computationally intensive, and provide results in a quick time frame compared to simulation models. However, they tend to be mathematically complex which means healthcare managers can find them difficult to understand, and are more reluctant to implement the solutions. Simulations are more data and computationally intensive compared to analytic models, but they are much easier to explain to healthcare managers when they are built in a user friendly environment. This means that managers tend to be more willing to introduce the results of the model into their department. Therefore, we use both analytic and simulation models in this work to utilise the benefits of both techniques. In this body of work a novel analytic cost model has been presented for a system which can be regarded as a network of M/M/∞ queues. The model considers the flow of patients through primary and secondary care, and is based on a mixture of Coxian phase-type models with multiple absorbing states. Costs are attached to each state of the model allowing the average cost per patient in the system to be calculated. We also provide a model which assesses whether the implementation of a new intervention is cost-effective. The model calculates the maximum cost the intervention can incur before the benefits no longer outweigh the cost of administering it. These analytic models have been applied to stroke patients deemed eligible for thrombolysis in order to assess the cost-effectiveness of thrombolytic therapy. We also present a novel simulation model for stroke patients, who are eligible for thrombolysis, in order to validate our analytic models. 'What-If' scenarios and Probabilistic Sensitivity Analysis have also been carried out to provide healthcare managers with more confidence in our models. An analytic model has been presented for a complex system of M / M / c queues in steady state. The model analyses the system to find bottlenecks and assesses whether the staff are being efficiently utilised. Two resource allocation models have then been defined: the first determines the minimum number of resources required within the department, and the second efficiently distributes the resources throughout the department. These resource allocation models have been applied to orthopaedic Integrated Clinical Assessment and Treatment Service (ICATS) data to reduce the current queues within the department. A novel simulation model has also been created for orthopaedic ICATS which includes extra variation and realistic features. This allows us to assess how robust and reliable our analytic models are, as the results are applied to our simulation model which has different assumptions. The novel analytic models provide very similar results to the simulation models built for each healthcare environment. This implies that our analytic models are robust and reliable even when applied to a department which includes different assumptions. Therefore, our analytic models will provide reliable results when healthcare managers need to make decisions in a short time frame. Simulation models have been found to be a good validation technique for analytic models, as healthcare managers understand them better. Extra components can also be easily included within a simulation model, such as complex distributions to represent the inter-arrival and service rate, and realistic features such as shift patterns.
21
UMEMURA, TOMONARI, RYO KOMIYAMA y KAZUHIRO YAMAMOTO. "NUMERICAL SIMULATION ON FLOW IN COLUMN CHROMATOGRAPHY". World Scientific Publishing, 2013. http://hdl.handle.net/2237/20053.
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Gunter, Simon. "Numerical simulation of non-isothermal flow problems". Thesis, Aberystwyth University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320936.
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Yang, Zhiyan. "Numerical simulation of incompressible and compressible flow". Thesis, University of Sheffield, 1989. http://etheses.whiterose.ac.uk/3485/.
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This thesis describes the development of a numerical solution procedure which is valid for both incompressible flow and compressible flow at any Mach number. Most of the available numerical methods are for incompressible flow or compressible flow only and density is usually chosen as a main dependent variable by almost all the methods developed for compressible flow. This practice limits the range of the applicability of these methods since density changes can be very small when Mach number is low. Even for high Mach number flows the existing time-dependent methods may be inefficient and costly when only the finial steady-state is of concern. The presently developed numerical solution procedure, which is based on the SIMPLE algorithm, solves the steady-state form of the Navier-stokes equations, and pressure is chosen as a main dependent variable since the pressure changes are always relatively larger than the density changes. This choice makes it possible that the same set of variables can be used for both incompressible and compressible flows. It is believed that Reynolds stress models would give better performance in some cases such as recirculating flow, highly swirling flow and so on where the widely used two equation k-e model performs poorly. Hence, a comparative study of a Reynolds stress model and the k-e model has been undertaken to assess their performance in the case of highly swirling flows in vortex throttles. At the same time the relative performance of different wall treatments is also presented. It is generally accepted that no boundary conditions should be specified at the outflow boundary when the outflow is supersonic, and all the variables can be obtained by extrapolation. However, it has been found that this established principle on the outflow boundary conditions is misleading, and at least one variable should be specified at the outflow boundary. It is also shown that the central differencing scheme should be used for the pressure gradient no matter whether it is subsonic or supersonic flow.
24
Ferrar, Mark David. "Simulation of packing and flow in composites". Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304986.
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Khobeiz, Mohamed Hussien. "Numerical simulation of viscous incompressible turbomachinery flow". Thesis, University of Sheffield, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338828.
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Zhang, Zhao Kang. "Downhole fluid flow simulation during tripping operations". Thesis, Robert Gordon University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364683.
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Batten, Paul. "Compressible flow simulation on a parallel computer". Thesis, University of Southampton, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358770.
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Jones, Dorian Phillip. "Parallel simulation of turbulent square duct flow". Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294548.
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James, Richard. "Numerical simulation of flow through fluidic flowmeters". Thesis, Cranfield University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282180.
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Geurts, Kevin Richard. "Stochastic simulation of non-Newtonian flow fields /". Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/9821.
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Al-Saad, Mohammed. "Blood flow simulation using smooth particle hydrodynamics". Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/105588/.
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Blood flow rheology is a complex phenomenon, and the study of blood flow in the human body system under normal and pathological conditions are considered to be of great importance in biomedical engineering. Consequently, it is important to identify the key parameters that influence the flow behaviour of blood. The characterisation of blood flow will also enable us to understand the flow parameters associated with physiological conditions such as atherosclerosis. Thrombosis plays a crucial role in stopping bleeding when a blood vessel is injured. Developing tools that can successfully study the influences of hemodynamics on thrombus formation in arteries and vessels are considered to be essential. This thesis describes the steps taken to develop computational tools that focus on using the meshless particle-based Lagrangian numerical technique, which is named the smoothed particle hydrodynamic (SPH) method, to study the flow behaviour of blood and to explore flow condition that induces the formation of thrombus in blood vessels. A weakly-compressible SPH method is used here to simulate blood flow inside vessels. The basic governing equations solved in the SPH are the mass and momentum conservation equations. Due its simplicity and effectiveness, the SPH method is employed here to simulate the process of thrombogenesis under the influence of various blood flow parameters. In the present SPH simulation, blood is modelled by particles that have the characteristics of plasma and platelets. To simulate a 3-dimensional coagulation of platelets which form a thrombus, the adhesion and aggregation process of platelets are modelled by an effective inter-particle force model. With these models, platelet motion in the flowing blood and platelet adhesion and aggregation are effectively coupled with viscous blood flow. In this study, the adhesion and aggregation of blood particles are performed inside vessels with various geometries and with different flow velocity scenarios. The capabilities of this strategy were evaluated by comparing the simulation results with existing numerical and experimental results. All of these cases realistically model the formation of thrombus including thrombus collapse and partial separation. This thesis is considered to be the first work that is dedicated to the SPH simulation of thrombus formation inside blood vessels with various geometries and under different flow conditions.
32
Zhang, Jie. "Numerical Simulation of Flow in Ozonation Process". Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5161.
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In the last two decades, Computational Fluid Dynamics (CFD) has shown great potential as a powerful and cost-efficient tool to troubleshoot existing disinfection contactors and improve future designs for the water and wastewater treatment utilities.
In the first part of this dissertation two CFD simulation methodologies or strategies for computing turbulent flow are evaluated in terms of the predicted hydraulic performance of contactors. In the LES (large eddy simulation) methodology, the more energetic, larger scales of the turbulence are explicitly computed or resolved by the grid. In the less computationally intensive RANS (Reynolds-averaged Navier-Stokes) methodology, only the mean component of the flow is resolved and the effect of the unresolved turbulent scales is accounted for through a turbulence model. For baffled contactors, RANS performs on par with the LES in predicting hydraulic performance indices. In this type of contactors, hydraulic performance is primarily determined by quasi-steady recirculating (dead) zones within the contactor chambers which are well-resolved in both RANS and LES. Testing of the RANS methodology is also performed for a wastewater stabilization pond leading to prediction of hydraulic performance indices in good agreement with field measurements. However, for column contactors, LES performs better than RANS due to the ability of the LES to resolve unsteady or unstable flow structure associated with spatial transition to turbulence which is important in the determination of the hydraulic performance of the contactor.
In the second part of this dissertation the RANS methodology is adapted in order to develop a novel modeling framework for ozone disinfection of drinking water. This framework is unique as it combines CFD with kinetics-based reaction modeling to predict disinfection performance and bromate formation for the first time. Bromate, a human health hazard, is an undesired by-product of the disinfection of drinking water via ozonation. The modeling framework is validated via application to a full-scale ozone contactor. Predictions of ozone and bromate concentrations are consistent with data from physical experiments.
33
Dong, Bonian. "Numerical simulation of two-dimensional lifting flow". Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/101182.
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The panel method is reviewed, in which linear polynomials are used to approximate the vorticity distribution on the surface of a body. Two new panel methods are developed, in which quadratic and cubic polynomials are used in an attempt to make the derivative of the velocity continuous along the surface of the body. But the results are not better than those obtained by choosing the linear polynomials as the interpolations. After the three interpolation schemes are critically evaluated, numerical examples, based on the linear scheme, are presented to illustrate some applications of the method. The flow around an airfoil in a wind tunnel is calculated, the separation of the laminar boundary layer is determined by solving the boundary-layer equations with a finite-difference scheme, and the stability of the boundary layer is investigated. It is found that the walls of the wind tunnel do not affect the separation and stability of the boundary layer significantly. Finally, the interaction of a fee vortex core with an airfoil near the ground is modeled. When the free vortex core passes the airfoil along a lower trajectory the airfoil experiences a very large thrust and suction. When along a upper trajectory, the lift and drag vary in a much smaller range. No significant effect of the ground on the airfoil is observed.M.S.
34
Yaacob, Zulkefli. "Modelling and simulation of transient gas flow". Thesis, University of Salford, 1996. http://usir.salford.ac.uk/26975/.
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One of the objectives of this research was to develop mathematical models for transient flow in a gas transmission system. Models were developed from the continuity and the momentum equations. Different approximations in the equations result in the formulation of two different sets of partial differential equations, and these are the hyperbolic and the parabolic models. The Partial Differential Equations were numerically solved by an implicit finite difference technique. A Four Point Scheme was use to approximate the pressures, flows and their partial derivatives. With this scheme a second order accuracy for both spatial and time variables was achieved for both hyperbolic and parabolic models. The nonlinear equation sets from the finite differences discretization process are solved by using a Newton-Raphson iterative procedure. This procedure resulted in the formation of a sparse Jacobian Matrix. This large matrix was then compacted algebraically to reduce the time of the numerical solution. Although an implicit finite difference approximation was used in simulating the models, the important of the correct choice of the magnitude of the temporal and spatial steps should not be overlooked, particularly for high frequency disturbances 'Aliasing' problems will occur if temporal or spatial steps which are too large relative to the frequency of disturbance are used. Comparisons between the response of the hyperbolic and the parabolic models with different input boundary conditions were performed. As a result, recommendations are made on how the different models should be used in simulating real pipeline systems.
35
Le, Roux Frederick Nicolaas. "The CFD simulation of an axial flow fan". Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4344.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The purpose of this project is to investigate the method and accuracy of simulating axial ow fans with three-dimensional axisymmetric CFD models. Two models are evaluated and compared with experimental fan data. Veri cation data is obtained from a prototype fan tested in a facility conforming to the BS 848 standards. The ow eld over the blade surfaces is investigated further with a visualization experiment comprising of a stroboscope and wool tufts. Good correlation is found at medium to high ow rates and recommendations are made for simulation at lower ow rates as well as test guidelines at the fan test facility. The results and knowledge gained will be used to amend currently used actuator disc theory for axial ow fan simulation.
AFRIKAANSE OPSOMMING: Die doel van hierdie projek is om die metode en akkuraatheid om aksiaalvloeiwaaiers met drie-dimensionele BVM modelle te simuleer, te ondersoek. Twee modelle word geëvalueer en met eksperimentele waaiertoetse vergelyk. Veri- kasie data is verkry vanaf 'n prototipe waaier wat in 'n fasiliteit getoets is en wat aan die BS 848 standaarde voldoen. Die vloeiveld oor die lemoppervlaktes word ondersoek met 'n visualisering eksperiment wat uit 'n stroboskoop en wolletjies bestaan. Goeie korrelasie word gevind vir medium tot hoë massavloeie en aanbevelings word gemaak vir die simulasie by laer massavloeie met riglyne vir toetswerk in die toets-fasiliteit. Die resultate en kennis opgedoen sal gebruik word in die verbetering van huidige aksieskyfteorie vir numeriese aksiaalvloeiwaaier simulasies.
36
Oner, Erdinc. "A SIMULATION APPROACH TO MODELING TRAFFIC IN CONSTRUCTION ZONES". Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1108146637.
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Seyedein, Seyed Hossein. "Simulation of fluid flow and heat transfer in impingement flows of various configurations". Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69587.
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Results of numerical simulation of two-dimensional flow field and heat transfer impingement due to laminar and turbulent single as well as multiple slot jets discharging normally into a confined channel are presented. Both low-Reynolds and high-Reynolds number versions of $k - epsilon$ models were used to model the turbulent jet flow. A control volume-based finite difference method was employed to solve the governing mass, momentum, turbulent kinetic energy, turbulent kinetic energy dissipation rate and energy equations in the turbulent impinging jet cases. A separate program was written based on a body-fitted coordinate system to predict the transport characteristics of multiple laminar jets impinging on a plate surface with an inclined upper confinement surface. The parameters studied include: the jet Reynolds number, nozzle-to-impingement surface spacing and for the inclined confinement surface cases, the angle of inclination of the upper surface. From the low-Reynolds number model studied it was found that models presented by Lam-Bremhorst and Launder-Sharma to be applicable to single turbulent jet impingement heat transfer predictions. Inclination of the confined surface so as to accelerate the exhaust flow was found to level the Nusselt number distribution on the impingement surface.
38
Pittard, Matthew Thurlow. "Large Eddy Simulation Based Turbulent Flow-induced Vibration of Fully Developed Pipe Flow". Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd295.pdf.
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Pittard, Matthew T. "Large eddy simulation based turbulent flow-induced vibration of fully developed pipe flow /". Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd295.pdf.
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Cai, Mingchao. "Modeling and numerical simulation for the coupling of surface flow with subsurface flow /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MATH%202008%20CAI.
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Koc, Gencer. "Simulation Of Flow Transients In Liquid Pipeline Systems". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12609018/index.pdf.
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ABSTRACT
SIMULATION OF FLOW TRANSIENTS IN LIQUID PIPELINE SYSTEMS
Koç, Genç
er M.S., Department of Mechanical Engineering Supervisor: Prof. Dr. O. Cahit Eralp November 2007, 142 pages In liquid pipeline systems, transient flow is the major cause of pipeline damages. Transient flow is a situation where the pressure and flow rate in the pipeline rapidly changes with time. Flow transients are also known as surge and Waterhammer which originates from the hammering sound of the water in the taps or valves. In liquid pipelines, preliminary design parameters are chosen for steady state operations, but a transient check is always necessary. There are various types of transient flow situations such as valve closures, pump trips and flow oscillations. During a transient flow, pressure inside the pipe may increase or decrease in an unexpected way that cannot be foreseen by a steady state analysis. Flow transients should be considered by a complete procedure that simulates possible transient flow scenarios and by the obtained results, precautions should be taken. There are different computational methods that can be used to solve and simulate flow transients in computer environment. All computational methods utilize basic v flow equations which are continuity and momentum equations. These equations are nonlinear differential equations and some mathematical tools are necessary to make these equations linear. In this thesis a computer program is coded that utilizes &ldquo
Method of Characteristics&rdquo
which is a numerical method in solving partial differential equations. In pipeline hydraulics, two partial differential equations, continuity and momentum equations are solved together, in order to obtain the pressure and flow rate values in the pipeline, during transient flow. In this thesis, MATLAB 7.1 is used as the programming language and obtained code is converted to a C# language to be able to integrate the core of the program with a user friendly Graphical User Interface (GUI). The Computer program is verified for different scenarios with the available real pipeline data and results of various reputable agencies. The output of the computer program is the tabulated pressure and flow rate values according to time indexes and graphical representations of these values. There are also prompts for users warning about possible dangerous operation modes of the pipeline components.
42
Wu, Wen-Yu y 吳文瑜. "Flow Simulation of Electrophoresis". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/51754661512241243850.
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碩士國立成功大學
機械工程學系
86
Electrophoresis is a technology of the separation of different charged particles. Particles suspended in an electrolyte, under the influence of an applied electric field, tend to migrate toward the electrode which has oppositesign of the particle charge. Moving particles in the electrolyte are alsosubjected to drag force. So the terminal velocity of a particle is determinedby its charge-to-mass ratio. Time consuming of detection, large size of the capillary and limited efficiency are the major drawbacks of the traditional electrophoresis apparatus. The latest trend of the electrophoresis is to combine with MEMS technology, which minimizes the size of the capillary and saves the cost and time of detection. In this paper, the mathematical models of electrophoretic separation are reviewed to help the determination of theelectrophoretic parameters. The influence of bending capillary on theefficiency of electrophoretic separation is also investigated. It is shownthat the efficiency of separation is reduced by the presence of bending capillary.
43
Ahmed, Forhad. "Simulation of puddle flow in planar flow casting". 2005. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=370368&T=F.
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Fortin, Michael. "Interactive Simulation of Fluid Flow". Thesis, 2011. http://spectrum.library.concordia.ca/7276/1/Fortin_MCompSc_S2011.pdf.
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The simulation of fluid flow on rectangular grids using a discretized version of the Navier Stokes Equations for incompressible fluid flow can be simultaneously described as an aesthetically pleasing and computationally intensive embarrassingly parallel problem.
Ideally, the aesthetics of the fluid simulation should, given some set of parameters, feel natural despite the synthetic nature of the underlying grids. This natural feel, paramount to the success of the system, should fool a person into believing that they are interacting with a real fluid.
The number of calculations and data accesses increases with the number of cells present in the rectangular grid upon which the fluid is simulated. An increased number of calculations are required for augmented accuracy, different external forces, and additional dimensions. Since it is a trivial task to increase the complexity of the simulation, interactivity becomes a challenge of balancing accuracy, stability, and detail against speed of execution.
A simple solution is to throw more processing power through increased instruction execution speeds or additional cores. Throwing additional cores at the problem strains the memory bus making it the point that slows down the simulation. Therefore for a given algorithm, respecting data locality and processor peculiarities can be used to minimize execution times.
This document introduces a means of caching corrected velocity fields, a task scheduler that attempts to maximize the usage of the cache on multi-core processors, and a na\"ive compression algorithm based on run-length encoding.
45
Cheng, Kuang-Jung y 鄭光榮. "Simulation of Turbulent Step Flow". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/57438274623924823285.
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碩士淡江大學
水資源及環境工程學系
86
Title of Thesis: Simulation of Turbulent Step Flow Total Pages: 55Key Word: turbulent, step flow, finite analytic methodName of Institute: Graduate Institute of Water Resources and Environment Engineering, Tamkang UniversityGraduate Date: June, 1998 Degree Conferred: Master of ScienceName of Student: Cheng Kuang-Jung Advisor: Dr. Luke Chen 鄭 光 榮 陳 俊 成 博士Abstract: This research uses Finite Analytic Method to simulate the Two-DimensionTurbulent Step Flow under the circumstances of low Reynold Number. We apply for K-ε-E model in the turbulent flow and uses Wall- Function near the wallsto simulate boundary sub-layer. By changing the Two- Dimension turbulent Step Flow geometry coefficient (Expansion Ratio) and Reynold Number to find out the location of its vortex center and Reattachement length. The results are: 1.When using Finite Analytic Method, we correctly use boundary profile inorder to respond to the real world. 2.The characteristics of laminar sub-layer can be showed when using Wall-function in the Non-separation Zone and computing time can also be reduced. 3.When the geometry coefficient E=1.5, and the Reynold Number is between 5000and 11000, its reattachment length(XＲ/h) is about 4.8. 4.When the geometry coefficient E=2.0, and the Reynold Number is between 5000and 11000, its reattachment length XＲ/h) is about 4.9.5.When the geometry coefficient E=3.0, and the Reynold Number is between 5000and 11000, its reattachment length(XＲ/h) is around 3.9.
46
Carlsson, Victor, Philip Isaac y Persson Adina. "Simulation of Viscosity-Stratified Flow". Thesis, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-413537.
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The aim of this project is to study the viscous Burgers' equation for the case where the viscosity is constant, but also when it contains a jump in viscosity. In the first case where the viscosity is constant, Burgers' is simply solved on a singular domain. For the case with jump in viscosity, Burgers' is solved on multiple domains with different viscosity. The different domains are then connected by applying inner boundary conditions at an interface in order to produce a singular solution. The inner boundary conditions are imposed using three different methods; simultaneous approximation term (SAT), projection and hybrid method, where the hybrid method is a combination of both the SAT and projection method. These methods are used in combination with a stable and high-order accurate summation by parts (SBP) finite difference approximation in MATLAB. The three methods are then compared to each other with respect to the least square error and the corresponding convergence rate to determine which method is the most preferable to use. The methods resulting in the highest convergence rates are the projection and the hybrid methods. These methods manage to live up to the expected convergence rates for all operators with different orders of accuracy and are therefore both good methods to use. However, the best method to use is the projection method since it is much simpler to implement than the two other methods but still achieves just as good convergence rates as the hybrid method.
47
Fang, Hsun-He y 方巽禾. "Simulation of Cross-flow Microfiltration by Multiphase Flow Model". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/06675461103661323109.
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碩士淡江大學
化學工程與材料工程學系碩士班
95
The study simulates cross-flow microfiltration by multiphase flow model. In order to discuss cake property and fouling mechanism, we experiment on cross-flow microfiltration. The data can be compared with simulation results and realize the property of cross-flow microfiltration. A filter membrane, made of mixed cellulose ester, with a mean pore size of 0.1 μm is used to filter 0.8 μm PMMA particles. On two-phase flow while varying suspension concentration and cross-flow velocity, we show that filtration rate is lowered with higher suspension concentration and lower cross-flow velocity, while average porosity is lowered as well. Also, we use Computational Fluid dynamics, CFD, software FLUENT6.2’s multiphase flow model to estimate cake growth and use force analysis to figure out fouling mechanism. Lastly, using results obtained from dynamic experiment, we know that cake average porosity is lower with filtration time, however, cake resistance is higher.
48
Yang, Deng-Shun y 楊登順. "Thermal-Flow Simulation of Plastics Extrusion Flow Distributor Design". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ex4kyb.
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碩士國立雲林科技大學
機械工程系
106
The traditional bottle process is produced by injection blow molding. Recently, an automatic production method which plastic is transported by continuous extrusion integrated rotary injection blow-molding has been proposed. It is distributed to multiple cavities through an extrusion distributor. However, these manufacturing process problems, including heater power, flow imbalance, uneven shear, temperature inhomogeneity and heat distortion, must be solved. This study begins with initial heater power simulations which we compare with actual power tests. These comparisons include temperature distribution and heat distortion. In-depth simulations to improve the average temperature of each flow channel, optimize the average temperature, and minimize the effect of temperature on flow. Finally, the flow balance analysis was performed to investigate factors other than temperature discrepancies between flow channels. The results show that the mold configuration and uncertain factors must be considered. However, comparisons of the temperature distribution simulations with the measurements reveal discrepancies mainly due to uncertainty in air convention conditions. Comparisons between simulations and measurements suggest different thermal convection coefficients for each location. Heat distortion measurements of the lower part reveal discrepancies with estimated value due to temperature inhomogeneity. A comparison between a heat distortion measurement of the whole distributor and estimated value shows that the heat distortion discrepancy of the distribution plate dues to different temperature between flow channels and measuring points. The temperature discrepancies between flow channels are mainly due to the heater configuration in the upper distribution cover and in the distribution plate. Fine tuning of the configuration was needed to further improve the simulation. The temperature discrepancies after this fine adjustment of the distribution plate configuration was further reduced by 5~6 ̊C. The flow imbalance is due to uneven shear rate, causing discrepancies of about 2%. Keywords: plastics extrusion, die transient heat transfer analysis, die heat distortion, die flow distributor design, die flow balancing, extrusion dies
49
Chen, Li —. Wen y 陳麗雯. "Laboratory In-Vehicle Guidance Simulator with Integrated Traffic Flow Simulation". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/22780879023431425367.
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碩士淡江大學
運輸管理學系
89
Recent development in Dynamic Route Guidance System (as a subsystem of Advanced Travel Information System) has called for more studies in the subject of users’ compliance behavior, which affect the effectiveness of the provided in-vehicle roue guidance information. Although field test may be promising in a long run, large initiated capital investment will be involved and may not be appropriate in the early stage of system development. Laboratory experiment provides an economical alternative approach to handle this particular issue with great flexibility. A prototype of laboratory simulator has therefore been established from previous studies in this institute under Dr. Tong''s supervision as a dedicated tool of controlled experiment to collect such observations due to economical and practical considerations. This simulator is a computer based simulation system to mimic the basic functions of a DRGS of which provides traffic condition, navigation, and route guidance information through screen display. This particular design (SIM 1.0) includes five modulus components: a display module, a record module, a data base module, a computation module and a user operation interface module, and has proven its capability from a series of completed experiments. The objective of this thesis is to modify and to extend the flexibility of the prototype simulator. Two major modifications needed are (1) to add the network selection function instead of a fixed (default) experiment network, and (2) to integrate a traffic simulation program onto this original prototype system to substitute original survey-based fixed-timed traffic data base. These two modifications will allow the further studies to in-cop with experiment design technique to investigate more in-depth issues regarding the trilateral interactions of user/traffic network/information with DRGS. Accomplished in this thesis are three tasks. Firstly, a preliminary survey was conducted to explore the role of traffic network characteristic (which we found that was largely ignored by transportation related research articles). Secondly, analysis of the original simulator program and the selection/decomposition of the specific traffic simulation program were performed in order to realize the integration with programs in different computer languages. Finally, a series of tests were carried out to ensure seamless integration Results of this study have clearly demonstrated the justification of the issue of network characteristic within a DRGS context and the successful limited modification to current simulator with a selected traffic simulation program DYNASMART. Possible full-scale integration issues were also presented in this thesis which leads to more challenges for further studies
50
(10709238), Yuanpei Zhao. "A Comparison of Air Flow Simulation Techniques in Architectural Design". Thesis, 2021.
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The fluid simulation in computer generates realistic animations of fluids by solving Navier-Stokes equation. The methods of simulation are divided into two types. The grid-based methods and particle-based methods. The former one is wildly used for scientific computation because of its precision of simulation while the latter one is used in visual effects, games and other areas requiring real-time simulation because of the less computation time it has.
The indoor airflow simulations with HVAC system in construction design is one specific application in scientific computation and uses grid-based simulation as the general-purpose simulation does. This study addresses the problem that this kind of airflow simulations in construction design using grid-based methods are very time consuming and always need designers to do pretreatment of the building model, which takes time, money, and effort. On the other hand, the particle-based methods would have less computation time with an acceptable accuracy in indoor airflow simulations because this kind of simulation does not require very high precision.
Then this study conducts a detailed and practical comparison of different fluid simulation algorithms in both grid-based methods and particle-based ones. This study's deliverable is a comparison between particle-based and grid-based methods in indoor airflow simulations with HVAC system.
The overall methodology used to arrive at the deliverables of this study will need two parts of work. The benchmark data is gathered from a CFD software simulation using FVM with a decent grid resolution. The particle-based data will be generated by simulation algorithms over the same set of room and furniture models implemented by OpenGL and CUDA. After the benchmark FVM simulation being conducted in a CFD software, the temperature field of airflow will be measured. After simulation, the temperature field are gained on each one of 4 particle-based simulation. A comparison standard is set and data will be analyzed to get the conclusion. The result shows that in a short simulation time period, after finding a proper number of particles, the particle-based method will achieve acceptable accuracy of temperature and velocity field while using much less time.