Type of Document Dissertation Author Cui, Jintao Author's Email Address cui@math.lsu.edu URN etd-06182010-143907 Title Multigrid Methods for Maxwell's Equations Degree Doctor of Philosophy (Ph.D.) Department Mathematics Advisory Committee

Advisor Name Title Brenner, Susanne C. Committee Chair Madden, James Committee Member Sung, Li-yeng Committee Member Tom, Michael M. Committee Member Wan, Xiaoliang Committee Member Rai, Suresh Dean's Representative Keywords

- Maxwell's equations
- nonconforming finite element methods
- discontinuous Galerkin methods
- graded meshes
- multigrid algorithms
Date of Defense 2010-05-11 Availability unrestricted AbstractIn this work we study finite element methods for two-dimensional Maxwell's equations and their solutions by multigrid algorithms. We begin with a brief survey of finite element methods forMaxwell's equations. Then we review the related fundamentals, such as Sobolev spaces, elliptic regularity results, graded meshes, finite element methods for second order problems, and multigrid

algorithms. In Chapter 3, we study two types of nonconforming finite element methods on graded meshes for a two-dimensional curl-curl and grad-div problem that appears in electromagnetics.

The first method is based on a discretization using weakly continuous P1 vector fields. The second method uses discontinuous P1 vector fields. Optimal convergence rates (up

to an arbitrary positive epsilon) in the energy norm and the L2 norm are established for both methods on graded meshes. In Chapter 4, we consider a class of symmetric discontinuous Galerkin methods for a model Poisson problem on graded meshes that share many techniques with the nonconforming methods in Chapter 3. Optimal order error estimates are derived in both the energy norm and the L2 norm. Then we establish the

uniform convergence of W-cycle, V-cycle and F-cycle multigrid algorithms for the resulting discrete problems. In Chapter 5, we propose a new numerical approach for two-dimensional Maxwell's equations that is based on the Hodge decomposition for divergence-free vector fields. In this approach, an approximate solution for Maxwell's equations can be obtained by solving

standard second order scalar elliptic boundary value problems. We illustrate this new approach by a P1 finite element method. In Chapter 6, we first report numerical results for multigrid

algorithms applied to the discretized curl-curl and grad-div problem using nonconforming finite element methods. Then we present multigrid results for Maxwell's equations based on

the approach introduced in Chapter 5. All the theoretical results obtained in this dissertation are confirmed by numerical experiments.

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