Thesis (M.S.)--Boise State University, 2009. / Includes abstract. Includes bibliographical references (leaf 34).

Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 165-174).

Thesis (Ph. D.)--University of Hong Kong, 1989.

Thesis (Ph. D.)--University of Hong Kong, 1988.

Thesis (M.S.)--University of Florida, 2002. / Title from title page of source document. Document formatted into pages; contains xi, 84 p.; also contains graphics. Includes vita. Includes bibliographical references.

No description available.

published_or_final_version / Mathematics / Master / Master of Philosophy

For any given complex algebraic ordinary differential equation (ODE), one major task of both pure and applied mathematicians is to find explicit meromorphic solutions due to their extensive applications in science. In 2010, Conte and Ng in [12] proposed a new technique for solving complex algebraic ODEs. The method consists of an idea due to Eremenko in [20] and the subequation method of Conte and Musette, which was first proposed in [9]. Eremenko’s idea is to make use of the Nevanlinna theory to analyze the value distribution and growth rate of the solutions, from which one would be able to show that in some cases, all the meromorphic solutions of the studied differential equation are in a class of functions called “class W”, which consists of elliptic functions and their degenerates. The establishment of solutions is then achieved by the subequation method. The main idea is to build subequations which have solutions that also satisfy the original differential equation, hoping that the subequations will be easier to solve. As in [12], the technique has been proven to be very successful in obtaining explicit particular meromorphic solutions as well as giving complete classification of meromorphic solutions. In this thesis, the necessary theoretical background, including the Nevanlinna theory and the subequation method, will be developed. The technique will then be applied to obtain all meromorphic stationary wave solutions of the real cubic Swift-Hohenberg equation (RCSH). This last part is joint work with Conte and Ng and will appear in Studies in Applied Mathematics [13]. RCSH is important in several studies in physics and engineering problems. For instance, RCSH is used as modeling equation for Rayleigh- B?nard convection in hydrodynamics [43] as well as in pattern formation [16]. Among the explicit stationary wave solutions obtained by the technique used in this thesis, one of them appears to be new and could be written down as a rational function composite with Weierstrass elliptic function. / published_or_final_version / Mathematics / Master / Master of Philosophy

Navier-Stokes equations (NSE), the governing equations of incompressible ows, and rotational Navier-Stokes equations (RNSE), which model incompressible rotating ows, are of great importance in many industrial applications. In this thesis, several selected preconditioners for solving NSE are compared and analyzed. These preconditioners are then modified for applying to RNSE. Understanding the physics behind NSE and RNSE is essential when studying these two equations. The derivation of NSE from the law of conservation of mass and law of conservation of momentum is described. RNSE is obtained by changing the frame of reference of NSE to a rotational frame. The rotating effect leads to the extra Coriolis force term in RNSE. The equations are then scaled to dimensionless form to eliminate the effect of physical units. In practice, numerical solution of NSE instead of analytic solution is considered. To apply numerical solvers in this thesis, NSE is discretized by backward differentiation formula in time and finite element method in space. The non-linear term is linearized by extrapolation. The existence and uniqueness of the finite element solutions to NSE are shown in this thesis. Discretization and linearization result in a system of linear equations which is of saddle point type. Generalized minimum residual method (GMRES) is applied to solve the saddle point system so as to improve efficiency. GMRES is combined with preconditioning technique to enhance the convergence. In this thesis, three preconditioners, pressure convection-diffusion (PCD) [18], least squares commutator (LSC) [11] and relaxed dimensional factorization preconditioner (RDF) [4], for non-rotational problems are considered and investigated. The performance of preconditioners is compared in terms of time step dependency, mesh size dependency and Reynolds number (Re) dependency. It is found that PCD shows time step and mesh size independence for small Reynolds number (Re = 500). RDF is the most stable preconditioner among three preconditioners, but it costs slow convergence, which contrasts to the results in [4]. Preconditioners PCD, LSC and RDF are modi_ed to deal with the Coriolis force term in RNSE. Discrete projection method (DPM) [24], an algorithm designed for RNSE, is also considered. This algorithm can also be viewed as a preconditioned iterative method. The time step and Ekman number (Ek) dependency of modi_ed preconditioners and DPM are compared. The numerical results indicates that LSC is the best preconditioner against time step and Ek. DPM is only the second best although it is designed for RNSE. PCD is the worst preconditioner as it shows high Ek dependency. / published_or_final_version / Mathematics / Master / Master of Philosophy