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1	Fourth order Multi-Time-Stepping Adams-Bashforth (MTSAB) scheme for NASA Glenn Research Center’s Broadband Aeroacoustic Stator Simulation (BASS) Code Allampalli, Vasanth 14 June 2010 (has links) No description available. Mechanical Engineering Multi-Time Step Adams-Bashforth scheme BASS code Fourth order
2	Contractivity-Preserving Explicit 2-Step, 6-Stage, 6-Derivative Hermite-Birkhoff–Obrechkoff Ode Solver of Order 13 Alzahrani, Abdulrahman January 2015 (has links) In this thesis, we construct a new optimal contractivity-preserving (CP) explicit, 2-step, 6-stage, 6-derivative, Hermite--Birkhoff--Obrechkoff method of order 13, denoted by HBO(13) with nonnegative coefficients, for solving nonstiff first-order initial value problems y'=f(t,y), y(t_0)=y_0. This new method is the combination of a CP 2-step, 6-derivative, Hermite--Obrechkoff of order 9, denoted by HO(9), and a 6-stage Runge-Kutta method of order 5, denoted by RK(6,5). The new HBO(13) method has order 13. We compare this new method, programmed in Matlab, to Adams-Bashforth-Moulton method of order 13 in PECE mode, denoted by ABM(13), by testing them on several frequently used test problems, and show that HBO(13) is more efficient with respect to the CPU time, the global error at the endpoint of integration and the relative energy error. We show that the new HBO(13) method has a larger scaled interval of absolute stability than ABM(13) in PECE mode. Contractivity preserving Adams-Bashforth–Moulton method omparing ODE solvers N-body simulation
3	Simulação em variáveis primitivas de escoamento incompressíveis com atualizacao direta e explícita para pressão Platte, Rodrigo Barcelos January 1998 (has links) No presente trabalho estudam-se diferentes técnicas explícitas, em diferenças finitas, no emprego de algoritmos do tipo velocidade-pressão para simulação de escoamentos incompressíveis. O método de resolução da pressão de maneira direta e explícita, introduzido por Bravo e Claeyssen [BRA 97a], é analisado. Faz-se uma aproximação para o erro causado por esta técnica, e verifica-se como isto afeta a equação da continuidade. As simulações são realizadas na cavidade quadrada, comparando-se os diferentes métodos e validando as aproximações realizadas no estudo do método de resolução da pressão. Além disso, simula-se o escoamento em cavidades profundas e rasas, observandose a formação de vórtices e distribuição de energia cinética. Simulações do escoamento na cavidade cúbica também são apresentadas. / In this work different explicit technics in finite defferences in the application of velocity-pressure algorithm to simulate incompressible flows have been studied. The direct and explicit method of pressure resolution, introduced by Bravo anel Claeyssen [BRA 97a] is analyzed. An approximation to the error caused by this method is made, anel how this affects the continuity equation is verified. The simulations are maele in a square cavity, comparing the differents methoels anel valielating the approximations maele in the study of the pressure resolution method. Besieles this, flow in eleep and shallow cavities is simulateel, observing the formation of vortices and kinetic energy distribution. Simulations of the flow in the cubical cavity are also considered.
4	Simulação em variáveis primitivas de escoamento incompressíveis com atualizacao direta e explícita para pressão Platte, Rodrigo Barcelos January 1998 (has links) No presente trabalho estudam-se diferentes técnicas explícitas, em diferenças finitas, no emprego de algoritmos do tipo velocidade-pressão para simulação de escoamentos incompressíveis. O método de resolução da pressão de maneira direta e explícita, introduzido por Bravo e Claeyssen [BRA 97a], é analisado. Faz-se uma aproximação para o erro causado por esta técnica, e verifica-se como isto afeta a equação da continuidade. As simulações são realizadas na cavidade quadrada, comparando-se os diferentes métodos e validando as aproximações realizadas no estudo do método de resolução da pressão. Além disso, simula-se o escoamento em cavidades profundas e rasas, observandose a formação de vórtices e distribuição de energia cinética. Simulações do escoamento na cavidade cúbica também são apresentadas. / In this work different explicit technics in finite defferences in the application of velocity-pressure algorithm to simulate incompressible flows have been studied. The direct and explicit method of pressure resolution, introduced by Bravo anel Claeyssen [BRA 97a] is analyzed. An approximation to the error caused by this method is made, anel how this affects the continuity equation is verified. The simulations are maele in a square cavity, comparing the differents methoels anel valielating the approximations maele in the study of the pressure resolution method. Besieles this, flow in eleep and shallow cavities is simulateel, observing the formation of vortices and kinetic energy distribution. Simulations of the flow in the cubical cavity are also considered.
5	Simulação em variáveis primitivas de escoamento incompressíveis com atualizacao direta e explícita para pressão Platte, Rodrigo Barcelos January 1998 (has links) No presente trabalho estudam-se diferentes técnicas explícitas, em diferenças finitas, no emprego de algoritmos do tipo velocidade-pressão para simulação de escoamentos incompressíveis. O método de resolução da pressão de maneira direta e explícita, introduzido por Bravo e Claeyssen [BRA 97a], é analisado. Faz-se uma aproximação para o erro causado por esta técnica, e verifica-se como isto afeta a equação da continuidade. As simulações são realizadas na cavidade quadrada, comparando-se os diferentes métodos e validando as aproximações realizadas no estudo do método de resolução da pressão. Além disso, simula-se o escoamento em cavidades profundas e rasas, observandose a formação de vórtices e distribuição de energia cinética. Simulações do escoamento na cavidade cúbica também são apresentadas. / In this work different explicit technics in finite defferences in the application of velocity-pressure algorithm to simulate incompressible flows have been studied. The direct and explicit method of pressure resolution, introduced by Bravo anel Claeyssen [BRA 97a] is analyzed. An approximation to the error caused by this method is made, anel how this affects the continuity equation is verified. The simulations are maele in a square cavity, comparing the differents methoels anel valielating the approximations maele in the study of the pressure resolution method. Besieles this, flow in eleep and shallow cavities is simulateel, observing the formation of vortices and kinetic energy distribution. Simulations of the flow in the cubical cavity are also considered.
6	Vliv přesnosti aritmetických operací na přesnost numerických metod / Numerical Methods Accuracy vs Precision of Arithmetic Kluknavský, František January 2012 (has links) Thesis is dedicated to evaluation of roundoff impact on numerical integration methods accuracy and effectivity. Contains theoretical expectations taken from existing literature, implementation of chosen methods, experimental measurement of attained accuracy under different circumstances and their comparison with regard to time complexity. Library contains Runge-Kutta methods to order 7 and Adams-Bashforth methods to order 20 implemented using C++ templates which allow optional arbitrary-precision arithmetic. Small models with known analytic solution were used for experiments.
7	Numerical methods for a four dimensional hyperchaotic system with applications Sibiya, Abram Hlophane 05 1900 (has links) This study seeks to develop a method that generalises the use of Adams-Bashforth to solve or treat partial differential equations with local and non-local differentiation by deriving a two-step Adams-Bashforth numerical scheme in Laplace space. The resulting solution is then transformed back into the real space by using the inverse Laplace transform. This is a powerful numerical algorithm for fractional order derivative. The error analysis for the method is studied and presented. The numerical simulations of the method as applied to the four-dimensional model, Caputo-Lu-Chen model and the wave equation are presented. In the analysis, the bifurcation dynamics are discussed and the periodic doubling processes that eventually caused chaotic behaviour (butterfly attractor) are shown. The related graphical simulations that show the existence of fractal structure that is characterised by chaos and usually called strange attractors are provided. For the Caputo-Lu-Chen model, graphical simulations have been realised in both integer and fractional derivative orders. / Mathematical Sciences / M. Sc. (Applied Mathematics) Chaotic system Hyperchaotic system Ordinary differential equation Initial value problem Laplace transform Adams-Bashforth Fractional calculus Atangana-Baleanu Partial differential equation Fractional differential equation 518.4 Initial value problems Laplace transformation Fractional calculus Differential equations, Partial Fractional differential equations
8	A Fractional Step Zonal Model and Unstructured Mesh Generation Frame-work for Simulating Cabin Flows Tarroc Gil, Sergi January 2021 (has links) The simulation of physical systems in the early stages of conceptual designs has shown to be a key factor for adequate decision making and avoiding big and expensive issues downstream in engineering projects. In the case of aircraft cabin design, taking into account the thermal comfort of the passengers as well as the proper air circulation and renovation can make this difference. However, current numerical fluid simulations (CFD) are too computationally expensive for integrating them in early design stages where extensive comparative studies have to be performed. Instead, Zonal Models (ZM) appear to be a fast-computation approach that can provide coarse simulations for aircraft cabin flows. In this thesis, a Zonal Model solver is developed as well as a geometry-definition and meshing framework, both in Matlab®, for performing coarse, flexible and computationally cheap flow simulations of user-defined cabin designs. On one hand, this solver consists of a Fractional Step approach for coarse unstructured bi-dimensional meshes. On the other, the cabin geometry can be introduced by hand for simple shapes, but also with Computational Aided Design tools (CAD) for more complex designs. Additionally, it can be chosen to generate the meshes from scratch or morph them from previously generated ones. / <p>The presentation was online</p> Zonal Model Thermal Comfort Fluid Simulation Aircraft Cabin Design NURBS Morphing Radial Basis Functions Meshing Co-located Mesh Unstructured Mesh Mesh Quality Mesh Smoothing Enlarged Orientation Theorem Fractional Step Method Boussinesq Adam Bashforth Helmholtz-Hodge Theorem Rhie and Chow Difference Schemes Gradient Evaluation Differential Heated Cavity Driven Cavity Draught Rate Aerospace Engineering Rymd- och flygteknik Fluid Mechanics and Acoustics Strömningsmekanik och akustik

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