Riemann Problems
Mostrando 1-12 de 14 artigos, teses e dissertações.
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1. Problemas de Riemann para um Sistema Simétrico de Duas Leis de Conservação / Riemann Problems for a Symmetrical System of Two Conservation Laws
Nesta dissertação determinamos as soluções do problema de Riemann para um sistema de duas leis de conservação escrito na forma normal segundo a classificação de Schaeffer-Shearer, em [9]. Através de mudanças de variáveis, Schaeffer-Shearer determinaram a forma normal para um sistema não linear de duas leis de conservação com um ponto umbílico
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 09/04/2010
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2. An unstructured grid implementation of high-order spectral finite volume schemes
The present work implements the spectral finite volume scheme in a cell centered finite volume context for unstructured meshes. The 2-D Euler equations are considered to represent the flows of interest. The spatial discretization scheme is developed to achieve high resolution and computational efficiency for flow problems governed by hyperbolic conservation
Journal of the Brazilian Society of Mechanical Sciences and Engineering. Publicado em: 2010-12
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3. A comparison of hyperbolic solvers II: ausm-type and Hybrid Lax-Wendroff-Lax-Friedrichs methods for two-phase flows
Riemann-solver based schemes are difficult and sometimes impossible to be applied for complex flows due to the required average state. Other methods that do not use Riemann-solvers are best suited for such cases. Among them, AUSM+, AUSMDV and the recently proposed Hybrid Lax-Friedrichs-Lax-Wendroff (HLFW) have been extended to two-phase flows. The eigenstruc
Brazilian Journal of Chemical Engineering. Publicado em: 2010-03
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4. Riemann Problems for a Symmetrical System of Two Conservation Laws / Problemas de Riemann para um Sistema Simétrico de Duas Leis de Conservação
In this dissertation we describe the solutions to the Riemann problem for a system of two conservation laws written in the normal from according to classification of Schaeffer-Shearer in [9]. Through changes of variables Schaeffer-Shearer determined the normal form for a nonlinear system of two conservation laws with an isolated umbilical point in state spac
Publicado em: 2010
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5. Central schemes for porous media flows
We are concerned with central differencing schemes for solving scalar hyperbolic conservation laws arising in the simulation of multiphase flows in heterogeneous porous media. We compare the Kurganov-Tadmor (KT) [3] semi-discrete central scheme with the Nessyahu-Tadmor (NT) [27] central scheme. The KT scheme uses more precise information about the local spee
Computational & Applied Mathematics. Publicado em: 2009
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6. The "upwind" scheme to the conservation laws and their application in simulation of 2D and 3D incompressible laminar and turbulent flows with free surfaces / Um esquema "upwind" para leis de conservação e sua aplicação na simulação de escoamentos incompressíveis 2D e 3D laminares e turbulentos com superfícies livres
Althought the PDEs that model conservation laws and fluid dynamics problems are well established, their numerical solutions have presented a continuing challenge. In particular, there are two challenges associated with the computation and the understanding of these problems, namely, formation of shocks and turbulence. Both challenges can be attributed to the
Publicado em: 2009
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7. Corda vibrante e telegrafo : estudo analitico de problemas modelados por equações diferenciais / Vibrating string and telegraphe : an analytical study of problems by differential equations
Efetua-se um estudo sistemático das equações diferenciais parciais, lineares, de segunda ordem e do tipo hiperbólico, isto é, aquelas equações que estão associadas com o problema envolvendo a propagação de ondas. Como uma aplicação, discute-se o problema de ondas de corrente e ondas de tensão, através da chamada equação do telégrafo, também
Publicado em: 2008
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8. Uma nova abordagem numérica para a injeção de traçadores em reservatórios de petróleo / A new numerical approach for the injection of tracers in petroleum reservoirs
The injection of tracers are used in the investigation of ows in heterogeneous porous media, in studies related to the simulation of miscible dispacements in petroleum reservoirs and the dispersion of contaminants in aquifers. In this work we present new algorithms for the numerical approximation of tracer injection problems. We discuss recent developments o
Publicado em: 2008
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9. A limit-method for solving period problems on minimal surfaces / Metodo limite para solução de problemas de periodos em superficies minimas
In this work we present the study and construction of minimal surfaces through an exclusive method. In 1762, Lagrange introduced the Minimal Surfaces Diferential Equation through the Calculus of Variations, and today the theory of such surfaces builds up an active and broad research area. We obtain new families of minimal surfaces based upon the Reverse Cons
Publicado em: 2007
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10. A note on the Riemann problem for the random transport equation
We present an explicit expression to the solution of the random Riemann problem for the 1D random linear transport equation. We show that the random solution is a similarity solution and the statistical moments have very simple expressions. Furthermore, we verify that the mean, the variance, and the 3rd central moment agree quite well with Monte Carlo simula
Computational & Applied Mathematics. Publicado em: 2007
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11. Ondas de Choques Transicionais Para Modelos Quadráticos de Duas Leis de Conservação / Transitional shocks waves for quadratic models of two conservation laws
Transitional shock waves arises in solution of initial values problems for non linear systems of conservation laws that are not strictly hyperbolic. These waves are discontinuous solutions that posses viscous profile but do not conform to the Lax characteristic criterion, where inequalities between the shock propagation speed and the characteristic speeds mu
Publicado em: 2007
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12. Transitional shocks waves for quadratic models of two conservation laws / Ondas de Choques Transicionais Para Modelos Quadráticos de Duas Leis de Conservação
Transitional shock waves arises in solution of initial values problems for non linear systems of conservation laws that are not strictly hyperbolic. These waves are discontinuous solutions that posses viscous profile but do not conform to the Lax characteristic criterion, where inequalities between the shock propagation speed and the characteristic speeds mu
Publicado em: 2007