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A similarity solution of the Navier-Stokes equations for two-dimensional flow in a porous-walled channelCox, Stephen Michael January 1989 (has links)
No description available.
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Predictions of wave and tidally induced oscillatory flows with Reynolds stress turbulence modelsWaywell, M. N. January 1995 (has links)
No description available.
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Boundary condition approximations for the Lax-Wendroff methodWarren, M. D. January 1986 (has links)
No description available.
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Viscous flow near a stationary contact lineAsadulla, M. January 1986 (has links)
No description available.
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A theoretical investigation of an averaged-structure eddy viscosity model applied to turbulent shear flowsKhossousi, A. A. January 1987 (has links)
No description available.
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A flow equation approach to semi-classical approximations : a comparison with the WKB methodThom, Jacobus Daniel 12 1900 (has links)
Thesis (MSc (Physics))--University of Stellenbosch, 2006. / The aim of this thesis is the semi-classical implementation of Wegner’s flow equations
and comparison with the well-established Wentzel-Kramers-Brillouin method. We do this
by converting operators, in particular the Hamiltonian, into scalar functions, while an
isomorphism with the operator product is maintained by the introduction of the Moyal
product. A flow equation in terms of these scalar functions is set up and then approximated
by expanding it to first order in ~. We apply this method to two potentials, namely the
quartic anharmonic oscillator and the symmetric double-well potential. Results obtained
via the flow equations are then compared with those obtained from the WKB method.
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Non-perturbative flow equations from continuous unitary transformationsKriel, Johannes Nicolaas 12 1900 (has links)
Thesis (MSc (Physics))--University of Stellenbosch, 2005. / The goal of this thesis is the development and implementation of a non-perturbative solution
method for Wegner’s flow equations. We show that a parameterization of the flowing Hamiltonian
in terms of a scalar function allows the flow equation to be rewritten as a nonlinear partial
differential equation. The implementation is non-perturbative in that the derivation of the PDE
is based on an expansion controlled by the size of the system rather than the coupling constant.
We apply this method to the Lipkin model and obtain very accurate results for the spectrum,
expectation values and eigenstates for all values of the coupling and in the thermodynamic limit.
New aspects of the phase structure, made apparent by this non-perturbative treatment, are
also investigated. The Dicke model is treated using a two-step diagonalization procedure which
illustrates how an effective Hamiltonian may be constructed and subsequently solved within this
framework.
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An Accelerated Method for Mean Flow Boundary Conditions for Computational AeroacousticsSamani, Iman January 2018 (has links)
No description available.
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Hosting Capacity for Renewable Generations in Distribution GridsJanuary 2018 (has links)
abstract: Nowadays, the widespread introduction of distributed generators (DGs) brings great challenges to the design, planning, and reliable operation of the power system. Therefore, assessing the capability of a distribution network to accommodate renewable power generations is urgent and necessary. In this respect, the concept of hosting capacity (HC) is generally accepted by engineers to evaluate the reliability and sustainability of the system with high penetration of DGs. For HC calculation, existing research provides simulation-based methods which are not able to find global optimal. Others use OPF (optimal power flow) based methods where
too many constraints prevent them from obtaining the solution exactly. They also can not get global optimal solution. Due to this situation, I proposed a new methodology to overcome the shortcomings. First, I start with an optimization problem formulation and provide a flexible objective function to satisfy different requirements. Power flow equations are the basic rule and I transfer them from the commonly used polar coordinate to the rectangular coordinate. Due to the operation criteria, several constraints are
incrementally added. I aim to preserve convexity as much as possible so that I can obtain optimal solution. Second, I provide the geometric view of the convex problem model. The process to find global optimal can be visualized clearly. Then, I implement segmental optimization tool to speed up the computation. A large network is able to be divided into segments and calculated in parallel computing where the results stay the same. Finally, the robustness of my methodology is demonstrated by doing extensive simulations regarding IEEE distribution networks (e.g. 8-bus, 16-bus, 32-bus, 64-bus, 128-bus). Thus, it shows that the proposed method is verified to calculate accurate hosting capacity and ensure to get global optimal solution. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2018
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A Unitary Perturbation Theory Approach to Real-Time Evolution in the Hubbard ModelKreye, Manuel 23 October 2019 (has links)
No description available.
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