Anoe Adaptive Multiscale Finite Element Model

A New Adaptive Multiscale Finite Element Method with Applications to High Contrast Interface Problems

In this thesis we show that the finite element error for the high contrast elliptic interface problem is independent of the contrast in the material coefficient under certain assumptions. The error estimate is proved using a particularly technical proof with construction of a specific function from the finite dimensional space of piecewise linear functions. We review the multiscale finite element method of Chu, Graham and Hou to give clearer insight. We present some generalisations to extend their work on a priori contrast independent local boundary conditions, which are then used to find multiscale basis functions by solving a set of local problems. We make use of their regularity result to prove a new relative error estimate for both the standard finte element method and the multiscale finite element method that is completely coefficient independent The analytical results we explore in this thesis require a complicated construction. To avoid this we present an adaptive multiscale finite element method as an enhancement to the adaptive local-global method of Durlofsky, Efendiev and Ginting. We show numerically that this adaptive method converges optimally as if the coefficient were smooth even in the presence of singularities as well as in the case of a realisation of a random field. The novel application of this thesis is where the adaptive multiscale finite element method has been applied to the linear elasticity problem arising from the structural optimisation process in mechanical engineering. We show that a much smoother sensitivity profile is achieved along the edges of a structure with the adaptive method and no additional heuristic smoothing techniques are needed. We finally show that the new adaptive method can be efficiently implemented in parallel and the processing time scales well as the number of processors increases. The biggest advantage of the multiscale method is that the basis functions can be repeatedly used for additional problems with the same high contrast material coefficient.

An Iteratively Adaptive Multiscale Finite Element Method with Application to Interface Problems

Multiscale Simulations for Electrochemical Devices

Environmental protection and sustainability are major concerns in today’s world, and a reduction in CO2 emission and the implementation of clean energy are inevitable challenges for scientists and engineers today. The development of electrochemical devices, such as fuel cells, Li-ion batteries, and artificial photosynthesis, is vital for solving environmental problems. A practical device requires designing of materials and operational systems; however, a multidisciplinary subject covering microscopic physics and chemistry as well as macroscopic device properties is absent. In this situation, multiscale simulations play an important role. This book compiles and details cutting-edge research and development of atomistic, nanoscale, microscale, and macroscale computational modeling for various electrochemical devices, including hydrogen storage, Li-ion batteries, fuel cells, and artificial photocatalysis. The authors have been involved in the development of energy materials and devices for many years. In each chapter, after reviewing the calculation methods commonly used in the field, the authors focus on a specific computational approach that is applied to a realistic problem crucial for device improvement. They introduce the simulation technique not only as an analysis tool to explain experimental results but also as a design tool in the scale of interest. At the end of each chapter, a future perspective is added as a guide for the extension of research. Therefore, this book is suitable as a textbook or a reference on multiscale simulations and will appeal to anyone interested in learning practical simulations and applying them to problems in the development of frontier and futuristic electrochemical devices.