Дисертації з теми "Heat transfer problems"
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Jones, Alastair Stephen. "Convection heat transfer problems." Thesis, Keele University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267356.
Повний текст джерелаHussein, Mohammed Sabah. "Coefficient identification problems in heat transfer." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/12291/.
Повний текст джерелаBuckley, Donovan O. "Solution of Nonlinear Transient Heat Transfer Problems." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/302.
Повний текст джерелаCopiello, Diego <1980>. "Multiobjective genetic algorithms applied to heat transfer problems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1218/1/copiello_diego_tesi.pdf.
Повний текст джерелаCopiello, Diego <1980>. "Multiobjective genetic algorithms applied to heat transfer problems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2009. http://amsdottorato.unibo.it/1218/.
Повний текст джерелаChick, Eric. "Problems in forced and free convection." Thesis, Keele University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241449.
Повний текст джерелаValha, Jan. "Interfacial instability and spray heat transfer problems of two phase flow." Thesis, Middlesex University, 1996. http://eprints.mdx.ac.uk/6408/.
Повний текст джерелаGoktolga, Mustafa Ugur. "Simulation Of Conjugate Heat Transfer Problems Using Least Squares Finite Element Method." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614787/index.pdf.
Повний текст джерелаquadrilateral and triangular elements for two dimensional problems, hexagonal and tetrahedron elements for three dimensional problems were tried. However, since only the quadrilateral and hexagonal elements gave satisfactory results, they were used in all the above mentioned simulations.
Pinto, Francesco <1978>. "Application of evolutionary techniques to energy transfer efficiency in heat transfer problems and low consumption buildings." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/419/1/Pinto.pdf.
Повний текст джерелаPinto, Francesco <1978>. "Application of evolutionary techniques to energy transfer efficiency in heat transfer problems and low consumption buildings." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/419/.
Повний текст джерелаBrown, Murray J. (Murray Jeffrey). "A program for solving heat and mass transfer problems on a PC /." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60443.
Повний текст джерелаMoore, Travis J. "Application of Variation of Parameters to Solve Nonlinear Multimode Heat Transfer Problems." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4254.
Повний текст джерелаWells, Robert G. "Laminar flow with an axially varying heat transfer coefficient." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101333.
Повний текст джерелаM.S.
Köck, Helmut [Verfasser]. "Experimental and numerical study on heat transfer problems in microelectronic devices / Helmut Köck." Aachen : Shaker, 2013. http://d-nb.info/1049382048/34.
Повний текст джерелаDe, Lima e. Silva Waldyr. "A front-tracking boundary element formulation for heat transfer problems with phase change." Thesis, University of Portsmouth, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386081.
Повний текст джерелаSweet, Erik. "ANALYTICAL AND NUMERICAL SOLUTIONS OF DIFFERENTIALEQUATIONS ARISING IN FLUID FLOW AND HEAT TRANSFER PROBLEMS." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2585.
Повний текст джерелаPh.D.
Department of Mathematics
Sciences
Mathematics PhD
Orlowska, Anna H. "An investigation of some heat transfer and gas flow problems relevant to miniature refrigerators." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:6d7b19e5-71ad-439e-9d1c-f10129ac9949.
Повний текст джерелаOjeda, Steven Matthew. "A cut-cell method for adaptive high-order discretizations of conjugate heat transfer problems." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90783.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 143-151).
Heat transfer between a conductive solid and an adjacent convective fluid is prevalent in many aerospace systems. The ability to achieve accurate predictions of the coupled heat interaction is critical in advancing thermodynamic designs. Despite their growing use, coupled fluid-solid analyses known as conjugate heat transfer (CHT) are hindered by the lack of automation and robustness. The mesh generation process is still highly dependent on user experience and resources, requiring time-consuming involvement in the analysis cycle. This thesis presents work toward developing a robust PDE solution framework for CHT simulations that autonomously provides reliable output predictions. More specifically, the framework is comprised of the following components: a simplex cut-cell technique that generates multi-regioned meshes decoupled from the design geometry, a high-order discontinuous Galerkin (DG) discretization, and an anisotropic output-based adaptation method that autonomously adapts the mesh to minimize the error in an output of interest. An existing cut-cell technique is first extended to generate fully-embedded meshes with multiple sub-domains. Then, a coupled framework that combines separate disciplines is developed, while ensuring compatibility between the cut-cell and mesh adaptation algorithms. Next, the framework is applied to high-order discretizations of the heat, Navier-Stokes, and Reynolds-Averaged Navier-Stokes (RANS) equations to analyze the heat flux interaction. Through a series of numerical studies, high-order accurate outputs solved on autonomously controlled cut-cell meshes are demonstrated. Finally, the conjugate solutions are analyzed to gain physical insight to the coupled interaction.
by Steven Matthew Ojeda.
S.M.
Van, Cong Tuan Son. "Numerical solutions to some inverse problems." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/38248.
Повний текст джерелаDepartment of Mathematics
Alexander G. Ramm
In this dissertation, the author presents two independent researches on inverse problems: (1) creating materials in which heat propagates a long a line and (2) 3D inverse scattering problem with non-over-determined data. The theories of these methods were developed by Professor Alexander Ramm and are presented in Chapters 1 and 3. The algorithms and numerical results are taken from the papers of Professor Alexander Ramm and the author and are presented in Chapters 2 and 4.
Sweet, Erik. "Analytical and numerical solutions of differential equations arising in fluid flow and heat transfer problems." Orlando, Fla. : University of Central Florida, 2009. http://purl.fcla.edu/fcla/etd/CFE0002889.
Повний текст джерелаBetencurte, da Silva Wellington. "Aplicação de filtros de partículas para a assimilação de dados em problemas de fronteira móvel." Phd thesis, Toulouse, INPT, 2012. http://oatao.univ-toulouse.fr/11752/1/betencurte.pdf.
Повний текст джерелаGorgulu, Ilhan. "Numerical Simulation Of Turbine Internal Cooling And Conjugate Heat Transfer Problems With Rans-based Turbulance Models." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615000/index.pdf.
Повний текст джерелаmodel, Shear Stress Transport k-&omega
model, Reynolds Stress Model and V2-f model, which became increasingly popular during the last few years, have been used at the numerical simulations. According to conducted analyses, despite a few unreasonable predictions, in the majority of the numerical simulations, V2-f model outperforms other first-order turbulence models (Realizable k-&epsilon
and Shear Stress Transport k-&omega
) in terms of accuracy and Reynolds Stress Model in terms of convergence.
Pratt, Brittan Sheldon. "An assessment of least squares finite element models with applications to problems in heat transfer and solid mechanics." Texas A&M University, 2008. http://hdl.handle.net/1969.1/85941.
Повний текст джерелаHasan, Hayder M. "Novel semi-implicit locally conservative Galerkin SILCG solvers : applications to one dimensional human circulation, heat transfer and ageing problems." Thesis, Swansea University, 2018. https://cronfa.swan.ac.uk/Record/cronfa48065.
Повний текст джерелаZhang, Huaibao. "HIGH TEMPERATURE FLOW SOLVER FOR AEROTHERMODYNAMICS PROBLEMS." UKnowledge, 2015. https://uknowledge.uky.edu/me_etds/64.
Повний текст джерелаHashim, Sithy Aysha Fazlie. "Heat transfer between two arbitrary shaped bodies in the jump regime with one body enclosed inside the other : a numerical study /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9953863.
Повний текст джерелаSilieti, Mahmood. "INVERSE BOUNDARY ELEMENT/GENETIC ALGORITHM METHOD FOR RECONSTRUCTION O." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3325.
Повний текст джерелаPh.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
PIZZOLATO, ALBERTO. "Topology optimization for energy problems." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2710567.
Повний текст джерелаPaipuri, Mahendra. "Comparison and coupling of continuous and hybridizable discontinuous Galerkin methods : application to multi-physics problems." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/471530.
Повний текст джерелаNeste trabalho é proposta uma formulação para acoplar os modelos continuous e hybridizable discontinuous Galerkin a fim de analisar problemas conjugados de transferência de calor. Este modelo é então usado para estudar a resposta térmica de perfis pultrudidos de secção tubular em polímero reforçado com fibras de vidro (GFRP) sob a acção do fogo. O primeiro passo desta tese é comparar a eficiência computacional dos métodos Continuous Galerkin (CG) e Hybridizable Discontinuous Galerkin (HDG) de elevada ordem para problemas de escoamento de fluidos incompressíveis para valores reduzidos do número Reynolds. Apenas exemplos bidimensionais e métodos directos são considerados no presente trabalho. Uma comparação exaustiva em termos de tempo de CPU e precisão para ambos os métodos de discretização é efectuada sob uma plataforma comum. Os resultados apresentados sugerem que, em termos do tempo de CPU requerido, o HDG pode ser mais eficiente que o CG, para um determinado grau. A estabilidade do HDG e CG é estudada usando uma solução fabricada que produz uma abrupta descontinuidade, confirmando que o HDG fornece soluções convergentes e suaves na presença de descontinuidades, enquanto o CG não conseguiu convergir devido à presença de oscilações numéricas. Em seguida, a solução do problema acoplado Navier-Stokes/convecção-difusão, utilizando a aproximação de Boussinesq, é formulada no contexto HDG e analisada usando soluções de referência. Uma estratégia de acoplamento entre os métodos HDG e CG é proposta no âmbito de operadores elípticos de segunda ordem. A formulação acoplada é implementada e suas propriedades de convergência são estabelecidas numericamente usando soluções fabricadas. Finalmente, a formulação acoplada proposta entre HDG e CG para a equação do calor é combinada com as equações acopladas de Navier-Stokes/convecção-difusão para formular um novo modelo de CG-HDG para resolver problemas de transferência de calor conjugado. Exemplos de referência são resolvidos usando o modelo proposto e validados com valores de literatura. A parte final da tese aplica a formulação proposta CG-HDG acoplada para prever a resposta térmica de uma secção transversal tubular de GFRP. A equação de radiosidade que governa a radiação interna é adicionada ao modelo acoplado CG-HDG. Os erros de discretização são calculados para estabelecer os intervalos de confiança para quantidades de interesse. Resultados considerando a geometria circular dos cantos da cavidade são apresentados. Estes estão dentro do intervalo de incerteza estimado. Os tempos de CPU requeridos para resolver os sistemas de equações lineares sugerem que o modelo proposto CG-HDG é mais eficiente do que o modelo CG-CG em todos os casos considerados.
En esta tesis se propone una formulación acoplada del método de los elementos finitos clásico (CG) y el método Hybridizable Discontinuous Galerkin (HDG) para la a solución de problemas térmicos conjugados. El modelo se utiliza para determinar la respuesta al fuego de Polímeros Reforzados con Fibras de Vidrio (GFRP) con sección tubular. El primer paso de la tesis es la comparación de la eficiencia computacional de CG y HDG de alto orden para problemas de flujo incompresible para número de Reynolds (Re) bajo. Se consideran sólo ejemplos 2D y métodos de resolución de sistemas lineales directos. Se presenta una comparación en términos de tiempo de CPU y precisión en la solución para ambas discretizaciones, bajo la misma plataforma de implementación. Los resultados sugieren que HDG puede ser más eficiente computacionalmente que CG en tiempo de CPU, para un grado fijado. La estabilidad de HDG y CG para Re alto se estudia con una solución manufacturada que produce un frente pronunciado, confirmando que HDG proporciona soluciones convergidas suaves en presencia de frentes verticales, en casos en que las oscilaciones numéricas de CG no permiten llegar a convergencia. A continuación, se plantea la solución del problema acoplado Navier-Stokes/convección-difusión, con la aproximación de Boussinesq, en el contexto del método HDG, y se analiza con experimentos numéricos. Se propone una formulación acoplada HDG-CG para la ecuación del calor. Se comprueban numéricamente las propiedades de convergencia del método propuesto. Finalmente, se combina la formulación acoplada propuesta para la ecuación del calor con el acoplamiento con la ecuaciones de Navier-Stokes en el dominio del fluido, creando una nueva formulación CG-HDG para problemas térmicos conjugados. Se consideran tests clásicos para validar los resultados comparando con la literatura existente. La parte final de la tesis aplica la formulación acoplada CG-HDG propuesta a la predicción de la respuesta térmica de secciones tubulares de GFRP, incluyendo radiosidad interna en el modelo. Se calculan estimas de los errores de discretización para determinar intervalos de confianza para las cantidades de interés. Se presentan resultados con geometría con esquinas curvas en la cavidad mostrando resultados dentro de los intervalos de incertidumbre estimados. El tiempo de CPU para la resolución de sistemas sugiere que el modelo CG-HDG propuesto es más eficiente que el clásico método CG-CG en todos los casos considerados.
This thesis proposes a coupled continuous and hybridizable discontinuous Galerkin formulation to solve conjugate heat transfer problems. This model is then used to find the thermal response of Glass Fiber Reinforced Polymer (GFRP) tubular cross-section under fire. The first step of this thesis is to compare the computational efficiency of high-order Continuous Galerkin (CG) and Hybridizable Discontinuous Galerkin (HDG) methods for incompressible fluid flow problems in low Reynolds number regimes. Only 2-D examples and direct solvers are considered in the present work. A thoroughly comparison in terms of CPU time and accuracy for both discretization methods is made under the same platform. Various results presented suggests that HDG can be more efficient than CG when the CPU time, for a given degree, is considered. The stability of HDG and CG is studied using a manufactured solution that produces a sharp boundary layer, confirming that HDG provides smooth converged solutions in the presence of sharp fronts whereas, CG failed to converge due to the presence of numerical oscillations. Following, the solution of the coupled Navier–Stokes/convection-diffusion problem, using Boussinesq approximation, is formulated within the HDG framework and analysed using numerical experiments and benchmark problems. A coupling strategy between HDG and CG methods is proposed in the framework of second-order elliptic operators. The coupled formulation is implemented and its convergence properties are established numerically by using manufactured solutions. Finally, the proposed coupled formulation between HDG and CG for heat equation is combined with the coupled Navier–Stokes/convection diffusion equations to formulate a new CG-HDG model for solving conjugate heat transfer problems. Benchmark examples are solved using the proposed model and validated with literature values. The final part of the thesis applies the proposed CG-HDG coupled formulation to predict the thermal response of the GFRP tubular cross-section. The radiosity equation that governs the internal radiation is added to the CG-HDG coupled model. Estimates of the discretization errors are computed in order to establish the confidence intervals for quantities of interest. Results with the geometry having curved corners in the cavity are presented and shown to be within the estimated uncertainty intervals. CPU times for the linear solver suggests that the proposed CG-HDG model is more efficient than CG-CG model in all the cases considered
Neste trabalho é proposta uma formulação para acoplar os modelos continuous e hybridizable discontinuous Galerkin a fim de analisar problemas conjugados de transferência de calor. Este modelo é então usado para estudar a resposta térmica de perfis pultrudidos de secção tubular em polímero reforçado com fibras de vidro (GFRP) sob a acção do fogo. O primeiro passo desta tese é comparar a eficiência computacional dos métodos continuous Galerkin (CG) e Hybridizable Discontinuous Galerkin (HDG) de elevada ordem para problemas de escoamento de fluidos incompressíveis para valores reduzidos do número Reynolds. Apenas exemplos bidimensionais e métodos directos são considerados no presente trabalho. Uma comparação exaustiva em termos de tempo de CPU e precisão para ambos os métodos de discretização é efectuada sob uma plataforma comum. Os resultados apresentados sugerem que, em termos do tempo de CPU requerido, o HDG pode ser mais eficiente que o CG, para um determinado grau. A estabilidade do HDG e CG é estudada usando uma solução fabricada que produz uma abrupta descontinuidade, confirmando que o HDG fornece soluções convergentes e suaves na presença de descontinuidades, enquanto o CG não conseguiu convergir devido à presença de oscilações numéricas. Em seguida, a solução do problema acoplado Navier-Stokes/convecção-difusão, utilizando a aproximação de Boussinesq, é formulada no contexto HDG e analisada usando soluções de referência. Uma estratégia de acoplamento entre os métodos HDG e CG é proposta no âmbito de operadores elípticos de segunda ordem. A formulação acoplada é implementada e suas propriedades de convergência são estabelecidas numericamente usando soluções fabricadas. Finalmente, a formulação acoplada proposta entre HDG e CG para a equação do calor é combinada com as equações acopladas de Navier-Stokes/convecção-difusão para formular um novo modelo de CG-HDG para resolver problemas de transferência de calor conjugado. Exemplos de referência são resolvidos usando o modelo proposto e validados com valores de literatura. A parte final da tese aplica a formulação proposta CG-HDG acoplada para prever a resposta térmica de uma secção transversal tubular de GFRP. A equação de radiosidade que governa a radiação interna é adicionada ao modelo acoplado CG-HDG. Os erros de discretização são calculados para estabelecer os intervalos de confiança para quantidades de interesse. Resultados considerando a geometria circular dos cantos da cavidade são apresentados. Estes estão dentro do intervalo de incerteza estimado. Os tempos de CPU requeridos para resolver os sistemas de equações lineares sugerem que o modelo proposto CG-HDG é mais eficiente do que o modelo CG-CG em todos os casos considerados.
En esta tesis se propone una formulación acoplada del método de los elementos finitos clásico (CG) y el método Hybridizable Discontinuous Galerkin (HDG) para la a solución de problemas térmicos conjugados. El modelo se utiliza para determinar la respuesta al fuego de Polímeros Reforzados con Fibras de Vidrio (GFRP) con sección tubular. El primer paso de la tesis es la comparación de la eficiencia computacional de CG y HDG de alto orden para problemas de flujo incompresible para número de Reynolds (Re) bajo. Se consideran sólo ejemplos 2D y métodos de resolución de sistemas lineales directos. Se presenta una comparación en términos de tiempo de CPU y precisión en la solución para ambas discretizaciones, bajo la misma plataforma de implementación. Los resultados sugieren que HDG puede ser más eficiente computacionalmente que CG en tiempo de CPU, para un grado fijado. La estabilidad de HDG y CG para Re alto se estudia con una solución manufacturada que produce un frente pronunciado, confirmando que HDG proporciona soluciones convergidas suaves en presencia de frentes verticales, en casos en que las oscilaciones numéricas de CG no permiten llegar a convergencia. A continuación, se plantea la solución del problema acoplado Navier-Stokes/conveccióndifusión, con la aproximación de Boussinesq, en el contexto del método HDG, y se analiza con experimentos numéricos. Se propone una formulación acoplada HDG-CG para la ecuación del calor. Se comprueban numéricamente las propiedades de convergencia del método propuesto. Finalmente, se combina la formulación acoplada propuesta para la ecuación del calor con el acoplamiento con la ecuaciones de Navier-Stokes en el dominio del fluido, creando una nueva formulación CG-HDG para problemas térmicos conjugados. Se consideran ejemplos clásicos para validar los resultados comparando con la literatura existente. La parte final de la tesis aplica la formulación acoplada CG-HDG propuesta a la predicción de la respuesta térmica de secciones tubulares de GFRP, incluyendo radiosidad interna en el modelo. Se calculan estimas de los errores de discretización para determinar intervalos de confianza para las cantidades de interés. Se presentan resultados con geometría con esquinas curvas en la cavidad mostrando resultados dentro de los intervalos de incertidumbre estimados. El tiempo de CPU para la resolución de sistemas sugiere que el modelo CG-HDG propuesto es más eficiente que el clásico método CG-CG en todos los casos considerados.
Yau, Xavier. "Modélisation numérique instationnaire pour la simulation du soudage TIG avec couplage plasma / bain de fusion." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0059/document.
Повний текст джерелаIn order to ensure total safety during maintenance operations within nuclear power plants, it is mandatory to preserve the optimal quality of the internal weld beads. To this end, we use Computational Magnetohydrodynamics to simulate adjacent phenomena within the plasma and the weld pool in order to improve the knowledge of welding operating process. One of the difficulties is to take into account the effects induced by the thermal gradient and the variations of surfactant element concentrations on the weld pool surface known as the Marangoni effect. In order to take into account all the physical phenomena at the plasma / weld pool interface, we use an interface tracking method (Arbitrary Lagrangian-Eulerian) to improve the simulation of weld pool with free surfaces. Subsequently, it enables to capture more precisely the interfacial forces such as the Marangoni effect, the arc pressure and the gravity, and improve vertical welding simulation. Thus, this work is part of the development of a tridimensional unsteady two-way coupling in order to overcome the Gaussian boundary condition used to model the heat transfer from plasma torch towards the work piece surface. Ultimately, we could obtain an unified model for an optimal welding process simulation
Anflor, Carla Tatiana Mota. "Otimização evolucionária e topológica em problemas governados pela equação de Poisson empregando o método dos elementos de contorno." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/17714.
Повний текст джерелаThis work presents the computational development and implementation of topology optimization techniques for problems governed by the Poisson equation. The boundary element method was the numerical technique chosen to solve the equations. Three different methodologies were developed aiming this objective. The first methodology is directed to the application of genetic algorithms to investigate how a domain previously populated with randomly placed cavities evolves during the optimization process, and to verify the resemblance of the final solution with a optimal design. The external boundaries remain fixed during the process, while the location and dimension of the cavities are optimized in order to extremize a given cost function. The performance of the proposed algorithm is verified with a number of examples and the results are discussed. The second methodology presents a numerical algorithm for topology optimization based on the evaluation of topological derivatives, using the total potential energy as the cost function. This procedure is an alternative to the traditional optimization techniques, avoiding design solutions containing intermediary material densities. Solids with anisotropic constitutive behavior are studied under Robin, Neumann and Dirichlet boundary conditions. A linear coordinate transformation approach is used to map the original problem into an isotropic one, where the optimization is carried out. The final solution is then mapped back to the original coordinate system. The proposed method was found to be an attractive way to solve this class of problems, since no interior mesh is necessary, which reduces significantly the computational cost of the analysis. In the last part of the present work the topological derivative approach was further developed to deal with the optimization of problems under simultaneous heat and mass transfer. Since the sensitivities for each differential equation are different, a weighting factor was used to evaluate the final sensitivities of the coupled problem. This allows the imposition of different priorities for each problem Several examples are presented and their results are compared with the literature, when available, in order to validate the proposed formulations.
Silva, Frank Werley Xavier da. "Análise da transferência simultânea de calor e massa nos processos de absorção de vapor em soluções binárias via GITT." Universidade Federal da Paraíba, 2010. http://tede.biblioteca.ufpb.br:8080/handle/tede/5424.
Повний текст джерелаCoordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The simultaneous heat and mass transfer phenomenon presents on the absorbers of the absorption refrigeration machine was studied by Generalized Integral Transform Technique GITT, for three practical interest cases with growing degree of difficulty in your mathematical formulation. The two first occur over an inclined flat plane with laminar flow regime. It is considered the fully developed flow and obtained the explicit velocity profile with constant thickness film. The adiabatic and isothermal wall is analyzed. The third case, that represent a real condition of operation occur over external surface of a single tube. It models the falling film on a tube where the thickness of the film varies along the perimeter. The phenomenon studied, classified like diffusion problem coupled, presents a strong couplement on the liquid-vapor interface and so, the energy and concentration equations are simultaneously solved. The solutions are obtained from two auxiliary eigenvalues problems for concentration and energy problems. Following the GITT formalism, a hybrid analyticnumerical solution to the potentials is described. Results of practical interest are found such as Sherwood and Nusselt numbers, mass flux in the interface and average potentials.
O fenômeno da transferência simultânea de calor e massa presente nos absorvedores das máquinas de refrigeração por absorção foi estudado pela Técnica da Transformada Integral Generalizada, do inglês Generalized Integral Transform Technique GITT, para três casos de interesse prático com crescente grau de dificuldade em sua formulação matemática. Os dois primeiros se referem a uma placa plana inclinada com escoamento em regime laminar, com perfil de velocidades conhecido e com a espessura da película constante ao longo do escoamento. Esta situação é examinada para as condições limites: parede adiabática e parede isotérmica. O terceiro caso, mais próximo da condição real de operação, modela o escoamento sobre um tubo onde a espessura da película varia ao longo do perímetro. O fenômeno, classificado como problema de difusão acoplado, apresenta um forte acoplamento na interface líquido-vapor e com isso as equações que representam as distribuições de energia e concentração da película líquida durante o escoamento, não podem ser solucionadas separadamente. A solução é construída com base em dois problemas auxiliares: um para a energia e outro para a concentração. Seguindo o formalismo da GITT, os potenciais são obtidos de forma híbrida analítico-numérico. Resultados de interesse práticos são obtidos como números de Sherwood e de Nusselt, bem como o fluxo de massa na interface e os potenciais médios.
Maia, Neto Alfredo dos Santos. "Simulação computacional do processo de soldagem MIG de uma junta de topo de chapas de aço inoxidável da série 304 com deposição de material." Universidade Federal de Uberlândia, 2014. https://repositorio.ufu.br/handle/123456789/14780.
Повний текст джерелаThis work presents a 3D computational/mathematical model to solve the heat diffusion equation with phase change, considering addition of material and complex geometry. The finite volume method was used and the computational code was implemented in C++, using Borland compiler. Experimental tests were carried out for validation of the model in question. It was used a material whose thermal properties, varying with temperature, are well known: the stainless steel AISI 304. In addition, an inverse technique based on Golden Section was implemented to estimate the heat flux supplied to the sample. Experimental temperatures were measured using thermocouples type J - in a total of 07 (seven) - all connected to the metal sheet and the Agilent 34970A datalogger. The metal had a \"V\" Groove of 45°. In this location was conducted the deposition of material on only one welding pass and the dimensions (width and height) were measured after welding. The thermal model was validated from comparisons between measured and calculated temperatures. The results were consistent and validated the computational/mathematical model proposed. An innovation presented in this work consists in the calculation and visualization of the dimensions of the welding pool during welding. The complex geometry obtained proves that more studies are needed and new models must be designed to clarify and explain the formation of welding pool during welding of metal sheet.
Desenvolve-se, neste trabalho, um modelo matemático/computacional 3D (tridimensional) de difusão de calor com mudança de fase, acréscimo de material e geometria complexa. O método de volumes finitos foi implementado em linguagem C, utilizando o compilador Borland. Foram realizados testes experimentais para a validação do modelo em questão. Usou-se um material cujas propriedades térmicas, variando com a temperatura, são bem conhecidas: o aço inox AISI 304. Além do modelo direto já citado, foi implementada uma técnica inversa para o cálculo do fluxo de calor. Utilizou-se neste caso a amplamente conhecida Seção Áurea: técnica que exige uma simplificação, fluxo de calor constante ao longo do tempo de soldagem. As temperaturas na chapa foram medidas utilizando termopares do tipo J - em um total de 07 (sete) - todos ligados ao datalogger Agilent 34970A. As medições foram feitas do lado oposto à tocha de soldagem. A chapa metálica possuía um chanfro em V de 45º. Neste local foi realizada a deposição de material (reforço) em somente um passe de soldagem. As dimensões da geometria do reforço (largura e altura) foram medidas depois da realização da soldagem. Em relação aos resultados, além da comparação entre as temperaturas medidas e calculadas, foi também determinada a eficiência térmica da soldagem. Os resultados foram consistentes e validaram o modelo matemático/computacional proposto. Uma inovação apresentada neste trabalho consiste no cálculo e visualização gráfica tridimensional da poça de fusão ao longo do tempo. A complexa geometria obtida comprova que mais estudos se fazem necessários e que novos modelos devem ser concebidos para esclarecer e explicar a formação da poça de fusão durante a soldagem de chapas metálicas.
Doutor em Engenharia Mecânica
Souccar, Adham W. "Heat Transfer and Mass Transfer with Heat Generation in Drops at High Peclet Number." University of Toledo / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1177603981.
Повний текст джерелаKilic, Ilker. "Heat And Mass Transfer Problem And Some Applications." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614140/index.pdf.
Повний текст джерелаWebster, Robert Samuel. "A numerical study of the conjugate conduction-convection heat transfer problem." Diss., Mississippi State : Mississippi State University, 2001. http://library.msstate.edu/etd/show.asp?etd=etd-04102001-144805.
Повний текст джерелаMbiock, Aristide. "Radiative heat transfer in furnaces : elliptic boundary value problem." Rouen, 1997. http://www.theses.fr/1997ROUEA002.
Повний текст джерелаMorales, Rebellon Juan Carlos. "Radiation exchange within enclosures of diffuse gray surfaces : the inverse problem /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаGaspar, Jonathan. "Fluxmétrie et caractérisation thermiques instationnaires des dépôts des composants face au plasma du Tokamak JET par techniques inverses." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4739/document.
Повний текст джерелаThis work deals with the successive resolution of two inverse heat transfer problems: the estimation of surface heat flux on a material and equivalent thermal conductivity of a surface layer on that material. The direct formulation is bidimensional, orthotropic (real geometry of a composite material), unsteady, non-linear and solved by finite elements. The studied materials are plasma facing components (carbon-carbon composite tiles) from Tokamak JET. The searched heat flux density varies with time and one dimension in space. The surface layers conductivity varies spatially and can vary with time during the experiment (the other thermophysical properties are temperature dependent). The two inverse problems are solved by the conjugate gradient method with the adjoint state method for the exact gradient calculation. The experimental data used for the first inverse problem resolution (surface heat flux estimation) is the thermogram provided by an embedded thermocouple. The second inverse problem uses the space and time variations of the surface temperature of the unknown surface layer (infrared thermography) for the conductivity identification. The confidence calculations associated to the estimated values are done by the Monte Carlo approach. The method developed during this thesis helps to the understanding of the plasma-wall interaction dynamic, as well as the kinetic of the surface carbon layer formation on the plasma facing components, and will be helpful to the design of the components of the future machines (WEST, ITER)
Rivale, Stephanie Dawn. "An expert study in heat transfer." Thesis, 2010. http://hdl.handle.net/2152/23491.
Повний текст джерелаtext
Kang, Guo-Jhang, and 康國章. "Study of Special Problems in Microscale Heat Transfer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/43444834700615912253.
Повний текст джерела逢甲大學
航空工程所
93
First of all, the thermal wave model is used in this study. Conventional Fourier conduction was modified by a relaxation time �鄛 between heat flux and temperature gradient. Micro-scale heat conduction in both a three dimensional orthotropic body and a two dimensional anisotropic body were studied in this study. Two coordinate transformation methods were applied to transform the orthotropic body and anisotropic body into isotropic body. Then the temperature solution in the isotropic body was obtained by the Green’s function solution method. The temperature distributions in both an orthotropic body and an anisotropic body were then available by the inverse coordinate transformation. The effect of thermal conductivity ratio in x1, x2, and, x3 directions on temperature distribution in an orthotropic body was investigate for different thermal Mach number. Furthermore, the effect of thermal conductivity ratio of k1, k2, and k12 on temperature solutions was also examined for different Mach numbers The numerical results were shown that both the speed of heat source and the thermal conductivity ratio had crucial impact on temperature distributions in the above mentioned bodies. The mechanism of four type of micro-scale heat conduction model, i.e., CV, dual-phase-lag (DPL), T-wave, and �鄛2-�賏2 models were examined. Will they violate the thermodynamic laws when the boundaries of one-dimensional slab are subjected to sudden heating or sudden cooling. These models were solved by the Laplace transform method and the Riemann sum approximation. The effect of �鄛2 and ����2 on temperature distributions in slab was studied. Finally, the numerical results were shown that the CV, T-wave, and �鄛2-�賏2 models violate the thermodynamic laws in certain cases.
Chun-TeLu and 盧峻德. "Hyperbolic Phase-Change Heat Transfer Problems By Using Hybrid Laplace Transfer Method." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/12947344385476329622.
Повний текст джерела國立成功大學
工程科學系碩博士班
100
As technology advances, the heat transfer behavior on a micro scale has graduallybeen taken seriously. There is not muchresearch about the micro-scale non-Fourier phase change heat transfer problems.The main focus of this paper is to use the hybrid Laplace transform method to investigate Fourier and non-Fourier phase change heat transfer problems. Hybrid Laplace transform method is used in the research, with one using Riemann sum approximation based on inverse Laplace transform method and the other using the same Riemann sum approximation and control volume method.The temperature recovery method is applied to solve numerical problem of latent heat in phase-change.To solve non-Fourier heat transfer laser problems, study focuses on the application of hybrid numerical method and the instability ensued from iteration. ∂θ(δ,0)/∂β and (∂^2 θ(δ,0))/(∂^2 δ)can lead to unstable numerical results.As a result, Laplace transform methodis applied alone with control volume method and the finite difference method to acquire modified differential term. Then comes the iteration that effectively resolves the oscillated problem. Without the oscillation, the more complicated laser heat source issue can be addressed. Using the proposed method of this thesis to calculate the non –Fourier heat transfer problems can obtain anaccurate result and solve more complicated non-Fourier phase change problem.Applying the hybrid Laplace transform method together with temperature recovery method can solve the Steven problemaccurately. The non-Fourier dual phase laser heat source phase change problem involves two processes: the melting and solidification.In melting, part of the laser energy is absorbed by latent heat, making a relatively higher point in temperature than the point that does not consider phase change.On the other hand, in solidification, the release of latent heat mitigates the thermal diffusion. That makes a relatively higher point in temperature than the point that does not consider phase change.
Chiang, Jaw-Yeong, and 江照勇. "Application of Grey Prediction to Inverse Heat Transfer Problems." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/66221404697119960269.
Повний текст джерела國立成功大學
機械工程學系碩博士班
96
This article applies Grey Prediction Method of Grey System Theory to improve the problem of errors in inverse operation due to the error of temperature measurement when analyze Inverse Heat Transfer Problems (IHTP) with Reversed Matrix Method. For IHTP, this research adopted Revered Matrix Method with Linear Least-squares Error Method to construct a linear inverse model. With finite difference method, we discretized governing equation that is designed to solve IHTP to construct a linear matrix equation. Through the re-arrangement of matrix equation, the unknown conditions (such as initial conditions, boundary conditions, thermal property or geometrical shape) could be demonstrated clearly and independently. Then substitute a small amount of successive measuring points temperature into the linear inverse model and solve the problems by Linear Least-squares Error Method. The process of inverse operation only need to measure a small amount points temperature to estimate the solution of IHTP, but in practical measurement of temperature, the errors of measurement of temperature are inevitable. Such errors will affect the accuracy of estimation value of inverse operation or even lead to an erroneous results. One of improvement method is to increase the number of temperature measurement points. Certainly, more accurate results of inverse operation we want to obtain, the number of measurement points we should increase. Therefore, this research uses the Grey Prediction Method to improve the defect with a hope that significant reduction of the number of practical temperature measurement points could also obtain the same accurate results of inverse operation. The small amount of direct temperature measurement points can increase to more amount of temperature points by Grey Prediction Method, and the temperatures of those increased points could still keep the correlations with previous temperatures from direct measurement. The increased number of temperature points could replace the number of temperature points that is necessary to increase for inverse operation. In other words, Grey Prediction Method could significantly reduce the number of practical temperature measurement points while keep the same accuracy as the results of inverse operation using a great number of direct temperature measurement points.
Syu, Liang-Chung, and 許亮中. "Parallel Computing Analysis of Solidification and Heat Transfer Problems." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/79299099581045961983.
Повний текст джерела國立成功大學
工程科學系碩博士班
93
There are many researches worked on solidification and heat transfer problems, such as the casting of sand mold, the fabrication of poly-Si thin films by using an excimer laser, the crystal growth of GaAs. When solving these problems with a single CPU computer, it may take a great deal of computing time or the node number is too big to solve the problems. The purpose of this paper is to use the parallel computing to solve the solidification and heat-transfer problem by dividing the computing domain. The numerical method is the finite difference method. To verify the feasibility of the parallel programs for solving the solidification and heat transfer problems set up in this work, firstly the one-dimensional and extended two-dimensional Stefan problems are applied. The linear system of difference equations for the two-dimensional problems is solved by using the sweep by line and Jacobi methods. After the computing results are analyzed, an optimum data-transfer mode between computers is proposed. Secondly, the Rathjen problem is utilized to prove that the parallel program and the data transfer mode can work for different boundary conditions. Finally, the computing method used in this paper is applied to the problem of the crystal growth of GaAs, which has a large node number and needs a great deal of computing time. From the computing results of the testing and practical problems, it can be verified that the parallel computing program with the proposed data-transfer mode is a feasible and appropriate way to solve a huge solidification and heat-transfer problem for different working conditions, such as different boundary conditions, numerical solvers, node numbers, etc. And the results of this study can be referred to in the future research.
Lin, Jae-Yuh, and 林傑毓. "A New Numerical Method for Transient Heat Transfer Problems." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/83234466129091307938.
Повний текст джерелаYao-HongWang and 王耀鋐. "Analysis of Solidification and Heat Transfer Problems with COMSOL." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/94132543508238850758.
Повний текст джерела國立成功大學
工程科學系碩博士班
100
Abstract This study is to use the software package COMSOL Multiphysics to analyze the nonlinear solidification or phase-change problems, the natural convection problems, the coupling of convection and solidification problems and the thermal problems in the designed Susceptor. The accuracy of COMSOL for solving nonlinear and discontinuous interface problems and that of the practical design problem are compared and analyzed. First, the Stefan and Rathjen solidification problems with exact solutions are investigated by using COMSOL. Furthermore, COMSOL is employed to study the natural convection problems and the convection and solidification problems in which the temperature and flow fields are coupled with each other. Finally, COMSOL is applied to the heater design of a Susceptor for obtaining the uniform temperature distribution. Inverse calculation is utilized to acquire the design parameters from the experimental data of the previously designed Susceptor. The heater design is modified by the COMSOL analysis. From the analysis results, it can be found that COMSOL works very well for the heater design of the Susceptor and for solving the coupling problems. However, the location prediction of the solid/liquid interface of a solidified problem is not very accurate.
Hsiang-WenTzeng and 曾相文. "Finite Element Analysis on Solidification and Heat Transfer Problems." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/24619717817468357692.
Повний текст джерела國立成功大學
工程科學系碩博士班
101
Phase-change in a solidification process is a very important physical phenomenon, in which the latent-heat effect cannot be ignored. In the thesis, the finite element method with different numerical schemes of handling the latent-heat effect is used to analyze the temperature distributions of phase-change heat transfer problems. In the work, the one-dimensional Stefan and the two-dimensional Rathjen problems are numerically studied. The effective specific heat and the specific heat/enthalpy methods are employed to deal with the latent-heat effect and the accuracy and CPU time of these schemes are compared and analyzed. From the results, it can be found that the latter method could solve the problems more accurately and faster than the former one. With different integration methods and numbers of integration points, the rectangle and triangle elements are utilized to study the phase-change problems. The total error is used to compare the solution accuracies of these schemes. The closed-form integration formula is not a good way applied to solve the solidification problems. The rectangle element could have the more accurate result than the triangle one.
Tsai, Pi-Fei, and 蔡璧妃. "Estimation of transient heat transfer coefficient for 2-D inverse heat conduction problems." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/53418219955040193227.
Повний текст джерела國立成功大學
機械工程學系碩博士班
95
The study applies the method of Laplace transform and the finite difference method in conjunction with the least-squares methods, the cubic spline and the measured temperature inside the test material to predict the transient heat transfer coefficient on the boundary for the two-dimensional transient inverse heat conduction problems. For the inverse algorithm of the study, the functional form of the heat transfer coefficient is unknown a priori. The whole spatial domain is first divided into p sub-intervals. A series of connected cubic polynomial functions in space and a linear function in time are then introduced to simulate the distribution of the unknown surface heat flux over space and time for the transient inverse heat conduction problem. The study investigates into the effects of p value, the initial guesses of the unknown coefficient, the measurement locations and the measurement errors on the estimated results. The results show that when there is no temperature measurement error, a good estimation on the surface heat flux and the heat transfer coefficient can be derived with the inverse algorithm. The estimated results seem to be not very sensitive to the initial guesses, the measurement locations and the p value. Nevertheless, the predictions agree with the correct results perfectly even if there exist measurement errors, except for the long time estimations. It means that the inverse algorithm of the study presents a good accuracy.
CHEN, ZE-MING, and 陳澤明. "New hybrid laplace transform/finite element method applied to transient heat transfer problems." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/39743621203490277757.
Повний текст джерелаKai-LunTseng and 曾楷倫. "Non-Fourier Phase-Change Heat Transfer Problems By Using Hybrid Laplace Transfer Method." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/16546756973882144080.
Повний текст джерела