An Overset Mesh Framework for the Hybridizable Discontinuous Galerkin Finite Element Method


Book Description

Computational simulations contain discretizations of both a physical domain and a mathematical model. In this dissertation, an overset mesh framework is used to discretize the physical domain, and the hybridizable discontinuous Galerkin (HDG) finite element method is used to discretize the mathematical model. It is proposed that using an overset mesh framework for the HDG method enables stable solutions to be computed for complex geometries and dynamic meshes. Overset mesh methods are chosen because they are efficient at decomposing geometrically complex domains. The HDG method was chosen because it provides solutions that are arbitrarily high-order accurate, reduces the size of the global discrete problem, and has the ability to solve elliptic, parabolic, and/or hyperbolic problems with a unified form of discretization. An overset mesh method can utilize an inherent property of the HDG method, the decomposition of the solution into global (face) and local (volume) parts. The global solution exists only on the cell boundaries; while, the local solution exists in the interior of each cell and is decoupled between neighboring cells. This decomposition introduces face-volume coupling in the weak form for degrees of freedom on cell boundaries, which is used as the foundation for the overset communication between subdomains.Ultimately, the goal of this work is to simulate full-scale hydrodynamic and fluid-structure interaction (FSI) problems. To achieve these simulations, the necessary building blocks must first be verified and validated in the overset-HDG framework. The building blocks demonstrated in this dissertation are steady convection-diffusion, linear elasticostatics, and pseudo-compressible Navier-Stokes in both Eulerian and arbitrary Lagrangian-Eulerian frames. Computational simulations are performed to demonstrate the applicability and accuracy of the overset-HDG algorithm.




hp-Version Discontinuous Galerkin Methods on Polygonal and Polyhedral Meshes


Book Description

Over the last few decades discontinuous Galerkin finite element methods (DGFEMs) have been witnessed tremendous interest as a computational framework for the numerical solution of partial differential equations. Their success is due to their extreme versatility in the design of the underlying meshes and local basis functions, while retaining key features of both (classical) finite element and finite volume methods. Somewhat surprisingly, DGFEMs on general tessellations consisting of polygonal (in 2D) or polyhedral (in 3D) element shapes have received little attention within the literature, despite the potential computational advantages. This volume introduces the basic principles of hp-version (i.e., locally varying mesh-size and polynomial order) DGFEMs over meshes consisting of polygonal or polyhedral element shapes, presents their error analysis, and includes an extensive collection of numerical experiments. The extreme flexibility provided by the locally variable elemen t-shapes, element-sizes, and element-orders is shown to deliver substantial computational gains in several practical scenarios.




An Invitation to the Theory of the Hybridizable Discontinuous Galerkin Method


Book Description

This monograph requires basic knowledge of the variational theory of elliptic PDE and the techniques used for the analysis of the Finite Element Method. However, all the tools for the analysis of FEM (scaling arguments, finite dimensional estimates in the reference configuration, Piola transforms) are carefully introduced before being used, so that the reader does not need to go over longforgotten textbooks. Readers include: computational mathematicians, numerical analysts, engineers and scientists interested in new and computationally competitive Discontinuous Galerkin methods. The intended audience includes graduate students in computational mathematics, physics, and engineering, since the prerequisites are quite basic for a second year graduate student who has already taken a non necessarily advanced class in the Finite Element method.




Discontinuous Galerkin Finite Element Methods for Shallow Water Flow


Book Description

This research has laid the groundwork for a robust computational infrastructure in the context of DG FEM that will significantly cut computational cost by applying fast and efficient state-of-the-art algorithms. The promising results provide motivation for future model development within the framework of a mixed element approach as well as the derivation of higher order numerical integration rules for triangular prism domains.



















Higher-Order Finite Element Methods


Book Description

The finite element method has always been a mainstay for solving engineering problems numerically. The most recent developments in the field clearly indicate that its future lies in higher-order methods, particularly in higher-order hp-adaptive schemes. These techniques respond well to the increasing complexity of engineering simulations and