Semester

Spring

Date of Graduation

2026

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Mathematics

Committee Chair

Qingtian Zhang

Committee Co-Chair

Charis Tsikkou

Committee Member

Dening Li

Committee Member

Adrian Tudorascu

Committee Member

Weichao Tu

Abstract

                                                       ABSTRACT

                   Global Weak Solutions of Optical Variational Wave System

                                        Shahrazad Hamed Mahal Alnafie

The coupling of a variational wave equation with Maxwell’s equations gives rise to the optical variational wave system, a hyperbolic PDE system that models the director field of the nematic liquid crystals. This system presents unique analytical challenges that have not been addressed in the existing literature. In this dissertation, we study the one-dimensional case of this system.

We establish the global existence of conservative weak solutions to the associated Cauchy problem. The hyperbolic system is derived using the energy variational method. Through a sequence of suitable coordinate transformations, we reformulate the system while preserving its hyperbolicity. Due to degeneracy arising from the change of variables, we construct a non-degenerate approximate sequence of solutions, prove local well-posedness, and establish pre-compactness of the approximate solution sequence. This allows us to pass to the limit in the original coordinates and prove the global existence of conservative weak solutions.

This result highlights the analytical significance of the optical variational wave system in liquid crystal theory and provides a rigorous foundation for future analytical work on this model in higher spatial dimensions.

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