This paper is about the computation of the stresses on a rigid body from a knowledge of the far field velocities in exterior Stokes and Oseen flows. The surface of the body is assumed to be bounded and smooth, and the body is assumed to move with constant velocity. We give fundamental solutions and derive boundary integral equations for the stresses. As it turns out, these integral equations are singular, and their null space is spanned by the normal to the body. We then discretize the problem by replacing the body by an approximating polyhedron with triangular faces. Using a collocation method, each integral equation delivers a linear system. Since its matrix approximates a singular integral operator, the matrix is ill-conditioned, and the solution is unstable. However, since we know that the problem is uniquely solvable in the hyperspace orthogonal to the normal, we use regularization methods to get stable solutions and project them in the normal direction onto the hyperspace. / Graduation date: 1999

Graduation date: 1991

No description available.

No description available.

published_or_final_version / Mathematics / Master / Master of Philosophy

published_or_final_version / Mathematics / Master / Master of Philosophy

This thesis investigates the polynomial collocation method for the numerical solution of Cauchy type integral equations and the use of those equations and the related numerical techniques to solve two practical problem in Acoustics and Aerodynamics. Chapters I and II include the basic background material required for the development of the main body of the thesis. Chapter I discusses a number of practical problems which can be modelled as a singular integral equations. In Chapter II the theory of those equations is given in great detail. In Chapter III the polynomial collocation method for singular integral equations with constant coefficients is presented. A particular set of collocation points, namely the zeros of the first kind Chebyshev polynomials, is shown to give uniform convergence of the numerical approximation for the cases of the index K = 0. 1. The convergence rate for this method is also given. All these results were obtained under slightly stronger assumptions than the minimum required for the existence of an exact solution. Chapter IV contains a generalization of the results in Chapter III to the case of variable coefficients. In Chapter V an example of a practical problem which results in a singular integral equation and which is successfully solved by the collocation method is described in substantial detail. This problem consists of the interaction of a sound wave with an elastic plate freely suspended in a fluid. It can be modelled by a system of two coupled boundary value problems - the Helmholtz equation and the beam equation. The collocation method is then compared with asymptotic results and a quadrature method due to Miller. In Chapter VI an efficient numerical method is developed for solving problems with discontinuous right-hand sides. Numerical comparison with other methods and possible extensions are also discussed.

本論文旨在討論複空間上的特殊拉格朗日子流行的各種建構方法。這些方法主要自R. Harvey, B. Lawson, D. Joyce, R. Bryanl 以及M. Haskins這幾位數學家發展及研究. 本文側重於擁有不同類型對稱位的特殊拉格朗日子流行的結構方法, 其中包指於n維環面群及特殊正交群不變的例子，以及直紋特殊拉格朗日子流行。除此之外,本論文也會討論以上建構方法所給出的具體制子。最後, 本文亦會討論一種可以建構擁有高虧格鏈的特殊拉格朗日子流行的方法。 / This thesis gives a survey on constructions of special Lagrangian submanifolds in C[superscript n]. These construction methods are mainly studied by Harvey and Lawson, D. Joyce, R. Bryant and M. Haskins. We mainly focus on special Lagrangian submanifolds with different kinds of symmetries. These include local constructions of T[superscript n] --and SO(n)--invariant examples, and ruled examples. We also discuss explicit examples arose from those constructions. Besides local constructions, a global gluing construction of special Lagrangian submanifolds with high genus links is also discussed. / Detailed summary in vernacular field only. / Lam, Yi Chun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 97-99). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Chapter 1 --- Introduction --- p.6 / Chapter 2 --- Preliminaries --- p.17 / Chapter 2.1 --- Special Lagrangian Geometry --- p.17 / Chapter 2.2 --- Special Legendrian Links --- p.23 / Chapter 2.3 --- Harmonic Maps --- p.25 / Chapter 2.4 --- Moment Maps --- p.28 / Chapter 2.5 --- Evolution Equation --- p.30 / Chapter 2.6 --- Background Materials from Analysis --- p.33 / Chapter 3 --- T[superscript n] invariant Special Lagrangian Submanifolds --- p.36 / Chapter 3.1 --- Basic Example --- p.36 / Chapter 3.2 --- U(1)[superscript n-2] invariant Special Lagrangian Cones in C[superscript n] --- p.37 / Chapter 3.2.1 --- General Construction --- p.37 / Chapter 3.2.2 --- Reduction of O.D.E. System --- p.40 / Chapter 3.2.3 --- The 3--dimensional Case --- p.48 / Chapter 4 --- SO(n)--invariant Special Lagrangian Submanifolds --- p.52 / Chapter 4.1 --- Basic Example --- p.52 / Chapter 4.2 --- Special Lagrangian Submanifolds with Fixed Loci --- p.54 / Chapter 4.2.1 --- Reduction to P.D.E --- p.55 / Chapter 4.2.2 --- The 3--Dimensional Case --- p.63 / Chapter 5 --- Ruled Special Lagrangian Submanifolds --- p.65 / Chapter 5.1 --- Normal Bundle of a Submanifold --- p.65 / Chapter 5.2 --- Twisted Normal Bundles --- p.69 / Chapter 5.3 --- The 3Dimensional Case --- p.72 / Chapter 5.3.1 --- Construction of Special Lagrangian Ruled 3-folds --- p.71 / Chapter 5.3.2 --- Explicit Examples --- p.75 / Chapter 5.4 --- Twisted Special Lagrangian Cones --- p.78 / Chapter 6 --- Other Constructions --- p.81 / Chapter 6.1 --- Analysis on U(1)invariant Special Lagrangian submanifolds --- p.81 / Chapter 6.1.1 --- Non-singular Solutions --- p.83 / Chapter 6.1.2 --- Existence of Singular Solutions --- p.84 / Chapter 6.1.3 --- Properties of Singular Solutions --- p.86 / Chapter 6.2 --- Harmonic Maps and Minimal Immersions --- p.87 / Chapter 6.3 --- Construction of Special Lagrangian 3-folds with High Genus Links --- p.92 / Bibliography --- p.97

Zhou, Qianwen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 80-87). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

這篇論文將對三維不可壓納維 - 斯托克斯方程的軸對稱解的正則性理論作綜述。 / 在第一章會先重溫一些經典的正則性結果，例如用於 Leray-Hopf 弱解上的Serrin類條件和用於適當弱解上的Caffarelli-Kohn-Nirenberg 類理論。 / 第二章會處理假設為無漩的軸對稱解，由 Uchovskii 和Ladyzhenskaya 提出的整體正則解的唯一存在的結果將包含在其中。 / 從第三章起，解的漩將不再被假設為零，在這熱門的研究領域中，一些值得注意的結果會包含在論文之中。 / In this thesis, a survey on the regularity theory for axisymmetric solutions to the 3D incompressible Navier-Stokes equations is conducted. / In chapter 1, some classical results such as the Serrin-type criteria on the Leray-Hopf weak solutions and the Ca arelli-Kohn-Nirenberg partial regularity theory on the suitable weak solutions to the equations are reviewed. / Chapter 2 deals with the axisymmetric solutions of the equations assuming the unknown velocity has no swirl. The existence result on the unique regular global-in-time solution by Uchovskii and Ladyzhenskaya is included. / In chapter 3, the swirl component of the unknown velocity is no longer assumed to be zero and some remarkable results on this hot research area are presented and discussed in the thesis. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lau, Tsz Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 49-51). / Abstracts also in Chinese. / Chapter 1 --- Classical Results on the 3D Incompressible Navier-Stokes Equations --- p.3 / Chapter 1.1 --- Introduction --- p.3 / Chapter 1.1.1 --- Backgrounds of the Equations --- p.3 / Chapter 1.1.2 --- A Boundary Value Problem on Pressure --- p.4 / Chapter 1.1.3 --- The Helmholtz-Leray Decomposition --- p.5 / Chapter 1.1.4 --- The Energy Equality --- p.6 / Chapter 1.1.5 --- The Leray-Hopf Weak Solution --- p.8 / Chapter 1.1.6 --- Foreword to the Regularity Problem --- p.9 / Chapter 1.2 --- Serrin's Regularity Result --- p.10 / Chapter 1.2.1 --- The Vorticity Form --- p.11 / Chapter 1.2.2 --- Regularity of the Vorticity --- p.12 / Chapter 1.2.3 --- The Biot-Savart Law and Parabolic Regularity --- p.13 / Chapter 1.2.4 --- Later Developments --- p.14 / Chapter 1.3 --- CKN Partial Regularity Theory --- p.14 / Chapter 1.3.1 --- Backgrounds and the Main Result --- p.14 / Chapter 1.3.2 --- A Local Conditions for Regularity of u --- p.16 / Chapter 1.3.3 --- The Blow-up Estimate --- p.19 / Chapter 1.3.4 --- Estimating the Singular Set --- p.22 / Chapter 1.3.5 --- Later Developments --- p.23 / Chapter 2 --- On Axially Symmetric Flows Without Swirl --- p.25 / Chapter 2.1 --- Introduction and the Main Result --- p.25 / Chapter 2.2 --- A Local-in-time Existence Result --- p.26 / Chapter 2.3 --- A Priori Estimate --- p.27 / Chapter 2.4 --- Proving the Global Existence Result --- p.31 / Chapter 3 --- On Axially Symmetric Flows with Non-zero Swirl --- p.32 / Chapter 3.1 --- Serrin's Type Regularity Conditions --- p.32 / Chapter 3.1.1 --- Backgrounds and the Main Result --- p.32 / Chapter 3.1.2 --- A Brief Discussion on the Proof --- p.33 / Chapter 3.1.3 --- Later Developments --- p.36 / Chapter 3.2 --- Lower Bound on the Blow-up Rate --- p.37 / Chapter 3.2.1 --- Backgrounds and the Main Result --- p.37 / Chapter 3.2.2 --- Construction of Suitable Weak Solutions --- p.38 / Chapter 3.2.3 --- Idea of the Proof --- p.40 / Chapter 3.2.4 --- Later Developments --- p.42 / Chapter 3.3 --- An Alternative Proof on Slow Blow-up --- p.43 / Chapter 3.3.1 --- Backgrounds and the Main Result --- p.43 / Chapter 3.3.2 --- Liouville Type Theorems --- p.44 / Chapter 3.3.3 --- The Re-scaling Procedure --- p.46 / Chapter 3.3.4 --- Later Developments --- p.47