Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, MathematicsSubject: search.filters.subject.Numerical solutions

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Now showing 1 - 5 of 5
  • Master Thesis
    Numerical Solution Methods for Boundary Value Problems for the Laplace Equation in Semi-Infinite Domains
    (01. Izmir Institute of Technology, 2023) Plattürk, Sabahat Defne; Tanoğlu, Gamze
    The essential purpose of this thesis is to get numerical solutions of the Laplace Equation Boundary Value Problems subject to Dirichlet and Mixed boundary conditions on doubly connected semi-infinite domains, namely the upper half plane and semi-infinite strips, using boundary integral equations. Conformal maps served as a tool to transform the doubly connected semi-infinite domains into a doubly connected bounded domain. Images of boundary conditions are evaluated and the accuracy of the conformal maps are investigated. Then each problem is reduced to a system of linear boundary integral equations by representing the solution to the boundary value problems as combinations of double- and single-layer potentials. In the case of Dirichlet boundary conditions, we used a modification that ensures the unique solvability of the system of Fredholm Integral Equations of the second kind. However, in the case of mixed boundary conditions, such a modification is not needed. After the investigations of uniqueness and existence of solutions to the constructed systems of integral equations of the second kind, the systems of equations are solved by using the Nyström method, based on quadrature rules. For the numerical integration of integral operators with continuous kernels, the trapezoidal rule is used. For the numerical integration of the kernels with logarithmic singularity, we first split off the singularity and apply an extremely accurate quadrature rule for the improper integrals. Error analysis for both numerical integration techniques are given in details and the accuracy of Nyström Method which depend on the quadrature method is explained. Different test cases are considered to check the accuracy of the method and the order of convergence and error results are illustrated by numerical examples.
  • Master Thesis
    A Compact Finite Difference Method of Lines for Solving Non-Linear Partial Differential Equations
    (01. Izmir Institute of Technology, 2022) Ismoilov, Shodijon; Tanoğlu, Gamze; Gürarslan, Gürhan
    In this thesis, an efficient numerical method is proposed for the numerical solution of the chemical reaction-diffusion model governed by a non-linear system of partial differential equations known as a Brusselator model. The method proposed is based on a combination of higher-order Compact Finite Difference schemes and stable time integrator known as an adaptive step-size Runge-Kutta method. The performance of adaptive step-size Runge-Kutta formula of fifth-order accurate in time and Compact Finite Difference scheme of sixth-order in space are investigated. The method is implemented to solve three test problems and reveals that the method is capable of achieving high efficiency, accuracy and reliability. The results obtained are sufficiently accurate compared to some available results in the literature.
  • Master Thesis
    Computation of the Convection Diffusion Equation by the Fourth Order Compact Finite Difference Method
    (Izmir Institute of Technology, 2015) Bajellan, Asan Ali Akbar Fatah; Tayfur, Gökmen
    This dissertation aims to develop various numerical techniques for solving the one dimensional convection–diffusion equation with constant coefficient. These techniques are based on the explicit finite difference approximations using second, third and fourth-order compact difference schemes in space and a first-order explicit scheme in time. The suggested scheme has been seen to be very accurate and a relatively flexible solution approach in solving the contaminant transport equation for Pe ≤ 5. For the solution, the combined technique has been used instead of conventional solution techniques. The accuracy and validity of the numerical model are verified. The computed results showed that the use of the current method in the simulation is very applicable for the solution of the convection-diffusion equation. The technique is seen to be alternative to existing techniques. This dissertation is divided into six chapters: The derivation of the convective diffusion equation is given in Chapter 2. The main idea behind the higher order finite difference technique is given in Chapter 3. The numerical approximations to CDE described with ten different explicit schemes are introduced in Chapter 4. The results of numerical experiments using second, third and fourth-order compact difference schemes are presented in Chapter 5. Chapter 6 is devoted to a brief conclusion. Finally the references are introduced at the end.
  • Master Thesis
    Convergence Analysis and Numerical Solutions of the Fisher's and Benjamin-Bono Equations by Operator Splitting Method
    (Izmir Institute of Technology, 2014) Zürnacı, Fatma; Tanoğlu, Gamze
    This thesis is concerned with the operator splitting method for the Fisher’s and Benjamin-Bono-Mahony type equations. We showthat the correct convergence rates inHs(R) space for Lie- Trotter and Strang splitting method which are obtained for these equations. In the proofs, the new framework originally introduced in (Holden, Lubich, and Risebro, 2013) is used. Numerical quadratures and Peano Kernel theorem, which is followed by the differentiation in Banach space are discussed In addition, we discuss the Sobolev space Hs(R) and give several properties of this space. With the help of these subjects, we derive error bounds for the first and second order splitting methods. Finally, we numerically check the convergence rates for the time step ∆t.
  • Master Thesis
    Uniformly Convergent Approximation on Special Meshes
    (Izmir Institute of Technology, 2007) Bingöl, Özgür; Neslitürk, Ali İhsan
    We consider finite difference methods for the approximation of one-dimensional convection-diffusion problem with a small parameter multiplying the diffusion term. An analysis of the centered difference and upwind difference schemes on equidistant meshes shows that these methods are not uniformly convergent in the discrete maximum norm. However, we show that the upwind method over a set of suitably distributed mesh points produce uniformly convergent approximations in the discrete maximum norm. We further investigate the upwind difference method for the approximation of the convection-diffusion problem with a point source. Theoretical findings are supported with the numerical results.