Topology Optimization of Convective Cooling System Designs

This research investigates an approach to finding the optimal geometry of convective cooling system structures for the enhancement of cooling performance. To predict the cooling effect of convective heat transfer, flow analysis is performed by solving the Brinkman-penalized Navier-Stokes equation, and the temperature profile is obtained from the homogenized thermal-transport equation. For accurate and cost-effective analysis, stabilized finite element methods (FEM) and the adjoint sensitivity method for the multiphysics system are implemented. Several stabilization methods with different definitions of their stabilization tensors and the Newton-Raphson iteration method are introduced to solve the governing equations. This study investigates numerical instabilities, such as velocity and pressure oscillation at the fluid-solid interfaces, which result from the fact that the non body-conforming mesh for the topology optimization method fails to capture the sharp change in velocity gradient with a high Reynolds number flow. These oscillations are not problematic at the system analysis level, but prevent the design from converging to an optimized shape at the design optimization level, creating element-scale cavities near the solid boundaries. Several stabilization methods are examined for their ability to alleviate the instabilities. The Galerkin/least-square method produces less oscillation in most cases but it is insufficient in resolving the convergence issue. The density and sensitivity filters do not effectively suppress the cavities at the design optimization level, while a move-limit scheme easily prevents this instability without significant increase in computational cost. The topology optimization method is applied to the convective cooling system design, by using the same configuration that was successfully used in designing the Navier-Stokes flow system. The main design purpose is to design a flow channel to maximize cooling efficiency. A numerical issue concerning the behavior of the Brinkman penalization is presented with example designs. The optimizer frequently ignores the Brinkman penalization and creates infeasible designs. To resolve this issue, a multi-objective function that also minimizes pressure drop is suggested. As design examples, 2D and 3D cooling channels are designed by the multi-objective function, and the effect of Reynolds and Prandtl number change is discussed.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91462/1/kjun_1.pd

Inovação auxiliada por computador (CAI): uma análise bibliométrica de artigos publicados entre 2004 e 2013

In recent decades, innovation has come to be seen as a crucial factor for the competitiveness of organizations. From a process little orderly, innovation has come to be systematized, with the establishment of tools, methodologies and theories. A variety of computer programs have been created to support innovation, giving rise to a new category of tools, which is being called Computer Aided Innovation (CAI). This exploratory research seeks to understand more precisely the concept of CAI, as well as identify key publications, authors, institutions and regions in which it has been developed, besides seeking to identify gaps and trends of the topics covered in the area. Given the purpose of the research, it was decided to use bibliometrics, which allows obtaining the information indicated from the analysis of the main databases related to CAI. The research consists of 217 articles, published between 2004-2013. The methodological procedures to develop the research involved the following steps: a) raise the state of the art regarding the Computed Aided Innovation; b) Survey and data collection of scientific papers on CAI; c) categorization and bibliometric analysis and d) classify and analyze the topics covered. The results obtained through the bibliometric analysis revealed that there were 378 different authors, and authors have increased an average of 34.7% from 2004 to 2013. When checking the adhesion of the Lotka´s law to the field of CAI, It was observed that 72.8% of the authors had only one publication, 15% more than proposed by Lotka, than the area of CAI does not adjust to this law. The most productive authors were Runhua Tan (complete count) and Noel Leon (direct counting). The most cited author was Gaetano Cascini. The most productive country in the world is China, with 41% of publications, as well as having the largest number of researchers (42% of total) and the largest number of institutions. However, the country with the greatest relevance is France, because the French articles had 30.4% of the citations. The more productive institution is Hebei Universi ty of Technology, China, with 16% of the articles. The institution most frequently cited is INSA Strasbourg, France. By analyzing the topics covered, it was realized that the "Idea Management" category is more developed and the category "Management Patent" is the one with the least amount of work. It is considered that this research has contributed to give visibility to researchers, institutions and countries that have contributed to the development of CAI, besides recognizing the theoretical core that serves as the foundation of knowledge of the area. The theme CAI is extremely important for the improvement of the innovation process, enabling to innovate more efficiently and effectively.Nas últimas décadas, a inovação passou a ser vista como um fator crucial para a competitividade das organizações. De um processo pouco ordenado, a inovação tem passado a ser sistematizada, com o estabelecimento de ferramentas, metodologias e teorias. Uma variedade de programas computacionais têm sido criadas para apoiar a inovação, dando origem a uma nova categoria de ferramentas, que vem sendo denominada Computer Aided Innovation (CAI), ou Inovação Auxiliada por Computador. Esta pesquisa, de característica exploratória, busca compreender com maior exatidão o conceito de CAI, bem como identificar as principais publicações, autores, instituições e regiões nas quais o assunto tem sido desenvolvido, além de buscar identificar as lacunas e tendências dos temas abordados na área. Dada a finalidade da pesquisa, decidiu-se pelo uso da bibliometria e da análise de conteúdo para alcançar os objetivos estabelecidos. O universo da pesquisa constitui -se de 217 artigos, publicados no período de 2004 a 2013. Os procedimentos metodológicos para desenvolver a pesquisa envolveram os seguintes passos: a) levantar o estado da arte no que se refere a Inovação Auxiliada por Computador; b) levantar e coletar os dados dos artigos científicos em CAI; c) categorizar e fazer análise bibliométrica e d) classificar e analisar os temas abordados. Os resultados obtidos, por meio da análise bibliométrica, revelaram que houve 378 autores diferentes, e que a média de autores aumentou em 30,4% de 2004 a 2013. Ao verificar a aderência da lei de Lotka à área de CAI, observou-se que 72,8% dos autores tiveram apenas uma publicação, sendo 15% a mais do que o proposto por Lotka, ou seja, a área de CAI não se ajusta a esta lei. Os autores mais produtivos foram Runhua Tan (contagem completa) e Noel León (contagem direta). O autor mais citado foi Gaetano Cascini. O país mais produtivo do mundo é a China, com 41% das publicações, além de possuir o maior número de pesquisadores (42% do total) e o maior número de instituições. No entanto, o país com a maior relevância é a França, pois os artigos franceses tiveram 30,4% das citações. A instituição mais produtiva é Hebei University of Technology da China, com 16% dos artigos. A instituição mais citada é INSA Strasbourg, França. Ao analisar os temas abordados, percebeu-se que a categoria “Gestão de Ideias” é mais desenvolvida e a categoria “Gestão de Patentes” é a que possui a menor quantidade de trabalhos. Considera-se que esta pesquisa contribuiu para dar visibilidade aos pesquisadores, instituições e países que tem contribuído para o desenvolvimento do CAI, além de reconhecer o núcleo teórico que serve de alicerce do conhecimento da área. O tema CAI é de suma importância para a melhoria do processo de inovação, possibilitando inovar com mais eficiência e eficácia

Marine Engines Performance and Emissions

This book contains a collection of peer-review scientific papers about marine engines’ performance and emissions. These papers were carefully selected for the “Marine Engines Performance and Emissions” Special Issue of the Journal of Marine Science and Engineering. Recent advancements in engine technology have allowed designers to reduce emissions and improve performance. Nevertheless, further efforts are needed to comply with the ever increased emission legislations. This book was conceived for people interested in marine engines. This information concerning recent developments may be helpful to academics, researchers, and professionals engaged in the field of marine engineering