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Title:	Nystrom methods for high-order CQ solutions of the wave equation in two dimensions
Author:	Wind-Andersen, Erli
View Online:	njit-etd2022-030 (xiii, 90 pages ~ 11.4 MB pdf)
Department:	Department of Mathematical Sciences
Degree:	Doctor of Philosophy
Program:	Mathematical Sciences
Document Type:	Dissertation
Advisory Committee:	Turc, Catalin C. (Committee co-chair) Petropoulos, Peter G. (Committee co-chair) Afkhami, Shahriar (Committee member) Shirokoff, David (Committee member) Perez Arancibia, Carlos (Committee member)
Date:	2022-05
Keywords:	Aucoustic scattering Electromagnetic scattering Integral equation Numerical analysis Partial differential equations Scientific computing
Availability:	Unrestricted
Abstract:	An investigation of high order Convolution Quadratures (CQ) methods for the solution of the wave equation in unbounded domains in two dimensions is presented. These rely on Nystrom discretizations for the solution of the ensemble of associated Laplace domain modified Helmholtz problems. Two classes of CQ discretizations are considered: one based on linear multistep methods and the other based on Runge-Kutta methods. Both are used in conjunction with Nystrom discretizations based on Alpert and QBX quadratures of Boundary Integral Equation (BIE) formulations of the Laplace domain Helmholtz problems with complex wavenumbers. CQ in conjunction with BIE is an excellent candidate to eventually explore numerical homogenization to replace a chaff cloud by a dispersive lossy dielectric that produces the same scattering. To this end, a variety of accuracy tests are presented that showcase the high-order in time convergence (up to and including fifth order) that the Nystrom CQ discretizations are capable of delivering for a variety of two dimensional single and multiple scatterers. Particular emphasis is given to Lipschitz boundaries and open arcs with both Dirichlet and Neumann boundary conditions.