Spelling suggestions: "subject:"particle hydrodynamic""
51 |
A Local Surface Reconstruction Algorithm for Surface Tension Simulation in Smoothed Particle HydrodynamicsLin, Yixin January 2020 (has links)
No description available.
|
52 |
Turbulence particle models for tracking free surfaces / Modèles particulaires turbulents pur suivre les surfaces libresShao, Songdong January 2005 (has links)
Two numerical particle models, the Smoothed Particle Hydrodynamics (SPH) and Moving Particle Semi-implicit (MPS) methods, coupled with a
sub-particle scale (SPS) turbulence model, are presented to simulate free surface flows. Both SPH and MPS methods have the advantages in that
the governing Navier¿Stokes equations are solved by Lagrangian approach and no grid is needed in the computation. Thus the free surface can be
easily and accurately tracked by particles without numerical diffusion. In this paper different particle interaction models for SPH and MPS methods
are summarized and compared. The robustness of two models is validated through experimental data of a dam-break flow. In addition, a series of
numerical runs are carried out to investigate the order of convergence of the models with regard to the time step and particle spacing. Finally the
efficiency of the incorporated SPS model is further demonstrated by the computed turbulence patterns from a breaking wave. It is shown that both
SPH and MPS models provide a useful tool for simulating free surface flows.
|
53 |
Design and numerical simulation of a linear shaped charge separation mechanism for first stage separation of the Ares I launch vehicleChambers, Nicholas Roy 02 May 2009 (has links)
This thesis developed a linear shaped charge (LSC) separation mechanism capable of severing the interstage skin for first stage separation of the Ares I launch vehicle. The derived LSC design solution was found using available data on Explosive Technology’s Jetcord LSC and from National Aeronautics and Space Administration (NASA) Marshall Space Flight Center’s (MSFC) desired characteristics. Mechanism components are designed after Minuteman III’s separation mechanism for first stage separation and NASA MSFC’s desired characteristics. Mechanism severance is verified through the use of the numerical method capability smoothed particle hydrodynamics that the hydrocode Autodyn offers. Three simulations are conducted to determine feasibility: the first of only the LSC exploding, to numerically validate the explosion process; the second of the LSC penetrating the target, to numerically validate the penetration process and failure mechanisms; and the last of the entire mechanism, to obtain information about the explosion, penetration, failure, and debris generated.
|
54 |
An MD-SPH Coupled Method for the Simulation of Reactive Energetic MaterialsWang, Guangyu 15 June 2017 (has links)
No description available.
|
55 |
Quantifying the Effects of Uncertainty in a Decentralized Model of the National Airspace SystemSherman, Stephanie Irene 08 June 2015 (has links)
The modernization of the National Air Traffic Control System is on the horizon, and with it, the possible introduction of autonomous air vehicles into the national airspace. Per the FAA Aerospace Forecast (FAA, 2013), U.S. carrier passenger traffic is expected to average 2.2 percent growth per year over the next 20 years with government statistics indicating that the average domestic load factor for airlines in 2014 was approximately 84.4 percent (US Department of Transportation, 2015). Adding to that demand, the potential introduction of unmanned and autonomous air vehicles motivates reconsideration of control schemes. One of the proposed solutions (Eby, 1994) would involve a decentralized control protocol. Equipping each aircraft with the information necessary to navigate safely through integrated airspace becomes an information sharing problem: how much information about other aircraft is required for a pilot to safely fly the gamut of a heavily populated airspace and what paradigm shifts may be necessary to safely and efficiently utilize available airspace? This thesis describes the development of a tool for testing alternative traffic management systems, centralized or decentralized, in the presence of uncertainty.
Applying a computational fluid dynamics-inspired approach to the problem creates a simulation tool to model both the movement of traffic within the airspace and also allows study of the effects of interactions between vehicles. By incorporating a Smoothed Particle Hydrodynamics (SPH) based model, discrete particle aircraft each carry a set of unique deterministic and stochastic properties. With this model, aircraft interaction can be studied to better understand how variations in the nondeterministic properties of the system affect its overall efficiency and safety. The tool is structured to be sufficiently flexible as to allow incorporation of different collision detection and avoidance rules for aircraft traffic management. / Master of Science
|
56 |
Resolução numérica de escoamentos compressíveis empregando um método de partículas livre de malhas e o processamento em paralelo (CUDA) / Numerical resolution of compressible flows employing a mesfree particle method and CUDAJosecley Fialho Góes 25 August 2011 (has links)
Os métodos numéricos convencionais, baseados em malhas, têm sido amplamente
aplicados na resolução de problemas da Dinâmica dos Fluidos Computacional.
Entretanto, em problemas de escoamento de fluidos que envolvem superfícies livres,
grandes explosões, grandes deformações, descontinuidades, ondas de choque etc., estes
métodos podem apresentar algumas dificuldades práticas quando da resolução destes
problemas. Como uma alternativa viável, existem os métodos de partículas livre de
malhas. Neste trabalho é feita uma introdução ao método Lagrangeano de partículas,
livre de malhas, Smoothed Particle Hydrodynamics (SPH) voltado para a simulação numérica
de escoamentos de fluidos newtonianos compressíveis e quase-incompressíveis.
Dois códigos numéricos foram desenvolvidos, uma versão serial e outra em paralelo,
empregando a linguagem de programação C/C++ e a Compute Unified Device Architecture
(CUDA), que possibilita o processamento em paralelo empregando os núcleos das
Graphics Processing Units (GPUs) das placas de vídeo da NVIDIA Corporation. Os resultados
numéricos foram validados e a eficiência computacional avaliada considerandose
a resolução dos problemas unidimensionais Shock Tube e Blast Wave e bidimensional
da Cavidade (Shear Driven Cavity Problem). / The conventional mesh-based numerical methods have been widely applied
to solving problems in Computational Fluid Dynamics. However, in problems involving
fluid flow free surfaces, large explosions, large deformations, discontinuities,
shock waves etc. these methods suffer from some inherent difficulties which limit
their applications to solving these problems. Meshfree particle methods have emerged
as an alternative to the conventional grid-based methods. This work introduces
the Smoothed Particle Hydrodynamics (SPH), a meshfree Lagrangian particle method
to solve compressible flows. Two numerical codes have been developed, serial and
parallel versions, using the Programming Language C/C++ and Compute Unified Device
Architecture (CUDA). CUDA is NVIDIAs parallel computing architecture that
enables dramatic increasing in computing performance by harnessing the power of
the Graphics Processing Units (GPUs). The numerical results were validated and the
speedup evaluated for the Shock Tube and Blast Wave one-dimensional problems and
Shear Driven Cavity Problem.
|
57 |
Desenvolvimento de um simulador numérico empregando o método Smoothed Particle Hydrodynamics para a resolução de escoamentos incompressíveis. Implementação computacional em paralelo (CUDA) / Numerical modelling of incompressible flows with the smoothed particles hydrodynamics method. Implementation of parallel numerical algorithms using CUDAMarciana Lima Góes 30 August 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho, foi desenvolvido um simulador numérico baseado no método
livre de malhas Smoothed Particle Hydrodynamics (SPH) para a resolução de escoamentos
de fluidos newtonianos incompressíveis. Diferentemente da maioria das versões
existentes deste método, o código numérico faz uso de uma técnica iterativa na determinação
do campo de pressões. Este procedimento emprega a forma diferencial de
uma equação de estado para um fluido compressível e a equação da continuidade a
fim de que a correção da pressão seja determinada. Uma versão paralelizada do simulador
numérico foi implementada usando a linguagem de programação C/C++ e a
Compute Unified Device Architecture (CUDA) da NVIDIA Corporation. Foram simulados
três problemas, o problema unidimensional do escoamento de Couette e os problemas
bidimensionais do escoamento no interior de uma Cavidade (Shear Driven Cavity
Problem) e da Quebra de Barragem (Dambreak). / In this work a numerical simulator was developed based on the mesh-free
Smoothed Particle Hydrodynamics (SPH) method to solve incompressible newtonian
fluid flows. Unlike most existing versions of this method, the numerical code uses an
iterative technique in the pressure field determination. This approach employs a differential
state equation for a compressible fluid and the continuity equation to calculate
the pressure correction. A parallel version of the numerical code was implemented
using the Programming Language C/C++ and Compute Unified Device Architecture
(CUDA) from the NVIDIA Corporation. The numerical results were validated and the
speed-up evaluated for an one-dimensional Couette flow and two-dimensional Shear
Driven Cavity and Dambreak problems.
|
58 |
Uma formulação implícita para o método Smoothed Particle Hydrodynamics / An implicit formulation for the Smoothed Particle Hydrodynamics MethodRicardo Dias dos Santos 17 February 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Em uma grande gama de problemas físicos, governados por equações diferenciais, muitas
vezes é de interesse obter-se soluções para o regime transiente e, portanto, deve-se empregar
técnicas de integração temporal. Uma primeira possibilidade seria a de aplicar-se métodos
explícitos, devido à sua simplicidade e eficiência computacional. Entretanto, esses métodos frequentemente
são somente condicionalmente estáveis e estão sujeitos a severas restrições na
escolha do passo no tempo. Para problemas advectivos, governados por equações hiperbólicas,
esta restrição é conhecida como a condição de Courant-Friedrichs-Lewy (CFL). Quando temse
a necessidade de obter soluções numéricas para grandes períodos de tempo, ou quando o
custo computacional a cada passo é elevado, esta condição torna-se um empecilho. A fim de
contornar esta restrição, métodos implícitos, que são geralmente incondicionalmente estáveis,
são utilizados. Neste trabalho, foram aplicadas algumas formulações implícitas para a integração
temporal no método Smoothed Particle Hydrodynamics (SPH) de modo a possibilitar o uso
de maiores incrementos de tempo e uma forte estabilidade no processo de marcha temporal.
Devido ao alto custo computacional exigido pela busca das partículas a cada passo no tempo,
esta implementação só será viável se forem aplicados algoritmos eficientes para o tipo de estrutura
matricial considerada, tais como os métodos do subespaço de Krylov. Portanto, fez-se um
estudo para a escolha apropriada dos métodos que mais se adequavam a este problema, sendo
os escolhidos os métodos Bi-Conjugate Gradient (BiCG), o Bi-Conjugate Gradient Stabilized
(BiCGSTAB) e o Quasi-Minimal Residual (QMR). Alguns problemas testes foram utilizados a
fim de validar as soluções numéricas obtidas com a versão implícita do método SPH. / In a wide range of physical problems governed by differential equations, it is often of
interest to obtain solutions for the unsteady state and therefore it must be employed temporal
integration techniques. One possibility could be the use of an explicit methods due to its
simplicity and computational efficiency. However, these methods are often only conditionally
stable and are subject to severe restrictions for the time step choice. For advective problems
governed by hyperbolic equations, this restriction is known as the Courant-Friedrichs-Lewy
(CFL) condition. When there is the need to obtain numerical solutions for long periods of time,
or when the computational cost for each time step is high, this condition becomes a handicap.
In order to overcome this restriction implicit methods can be used, which are generally unconditionally
stable. In this study, some implicit formulations for time integration are used in the
Smoothed Particle Hydrodynamics (SPH) method to enable the use of larger time increments
and obtain a strong stability in the time evolution process. Due to the high computational cost
required by the particles tracking at each time step, the implementation will be feasible only if
efficient algorithms were applied for this type of matrix structure such as Krylov subspace methods.
Therefore, we carried out a study for the appropriate choice of methods best suited to this
problem, and the methods chosen were the Bi-Conjugate Gradient (BiCG), the Bi-Conjugate
Gradient Stabilized (BiCGSTAB) and the Quasi-Minimal Residual(QMR). Some test problems
were used to validate the numerical solutions obtained with the implicit version of the SPH
method.
|
59 |
Desenvolvimento de um simulador numérico empregando o método Smoothed Particle Hydrodynamics para a resolução de escoamentos incompressíveis. Implementação computacional em paralelo (CUDA) / Numerical modelling of incompressible flows with the smoothed particles hydrodynamics method. Implementation of parallel numerical algorithms using CUDAMarciana Lima Góes 30 August 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho, foi desenvolvido um simulador numérico baseado no método
livre de malhas Smoothed Particle Hydrodynamics (SPH) para a resolução de escoamentos
de fluidos newtonianos incompressíveis. Diferentemente da maioria das versões
existentes deste método, o código numérico faz uso de uma técnica iterativa na determinação
do campo de pressões. Este procedimento emprega a forma diferencial de
uma equação de estado para um fluido compressível e a equação da continuidade a
fim de que a correção da pressão seja determinada. Uma versão paralelizada do simulador
numérico foi implementada usando a linguagem de programação C/C++ e a
Compute Unified Device Architecture (CUDA) da NVIDIA Corporation. Foram simulados
três problemas, o problema unidimensional do escoamento de Couette e os problemas
bidimensionais do escoamento no interior de uma Cavidade (Shear Driven Cavity
Problem) e da Quebra de Barragem (Dambreak). / In this work a numerical simulator was developed based on the mesh-free
Smoothed Particle Hydrodynamics (SPH) method to solve incompressible newtonian
fluid flows. Unlike most existing versions of this method, the numerical code uses an
iterative technique in the pressure field determination. This approach employs a differential
state equation for a compressible fluid and the continuity equation to calculate
the pressure correction. A parallel version of the numerical code was implemented
using the Programming Language C/C++ and Compute Unified Device Architecture
(CUDA) from the NVIDIA Corporation. The numerical results were validated and the
speed-up evaluated for an one-dimensional Couette flow and two-dimensional Shear
Driven Cavity and Dambreak problems.
|
60 |
Resolução numérica de escoamentos compressíveis empregando um método de partículas livre de malhas e o processamento em paralelo (CUDA) / Numerical resolution of compressible flows employing a mesfree particle method and CUDAJosecley Fialho Góes 25 August 2011 (has links)
Os métodos numéricos convencionais, baseados em malhas, têm sido amplamente
aplicados na resolução de problemas da Dinâmica dos Fluidos Computacional.
Entretanto, em problemas de escoamento de fluidos que envolvem superfícies livres,
grandes explosões, grandes deformações, descontinuidades, ondas de choque etc., estes
métodos podem apresentar algumas dificuldades práticas quando da resolução destes
problemas. Como uma alternativa viável, existem os métodos de partículas livre de
malhas. Neste trabalho é feita uma introdução ao método Lagrangeano de partículas,
livre de malhas, Smoothed Particle Hydrodynamics (SPH) voltado para a simulação numérica
de escoamentos de fluidos newtonianos compressíveis e quase-incompressíveis.
Dois códigos numéricos foram desenvolvidos, uma versão serial e outra em paralelo,
empregando a linguagem de programação C/C++ e a Compute Unified Device Architecture
(CUDA), que possibilita o processamento em paralelo empregando os núcleos das
Graphics Processing Units (GPUs) das placas de vídeo da NVIDIA Corporation. Os resultados
numéricos foram validados e a eficiência computacional avaliada considerandose
a resolução dos problemas unidimensionais Shock Tube e Blast Wave e bidimensional
da Cavidade (Shear Driven Cavity Problem). / The conventional mesh-based numerical methods have been widely applied
to solving problems in Computational Fluid Dynamics. However, in problems involving
fluid flow free surfaces, large explosions, large deformations, discontinuities,
shock waves etc. these methods suffer from some inherent difficulties which limit
their applications to solving these problems. Meshfree particle methods have emerged
as an alternative to the conventional grid-based methods. This work introduces
the Smoothed Particle Hydrodynamics (SPH), a meshfree Lagrangian particle method
to solve compressible flows. Two numerical codes have been developed, serial and
parallel versions, using the Programming Language C/C++ and Compute Unified Device
Architecture (CUDA). CUDA is NVIDIAs parallel computing architecture that
enables dramatic increasing in computing performance by harnessing the power of
the Graphics Processing Units (GPUs). The numerical results were validated and the
speedup evaluated for the Shock Tube and Blast Wave one-dimensional problems and
Shear Driven Cavity Problem.
|
Page generated in 0.1254 seconds