Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 16 of 16 for “"Riemann problem"”.
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On Shock Capturing for Liquid and Gas Media
… for internal energy is absent poses special problems. Classically, for gas dynamics the usual procedure is to employ a splitting scheme to remove the source terms from the Euler equations, then up-wind biased shock capturing algorithms are built around the Riemann problem for the system which …
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Multiphase Fluid-Material Interaction: Efficient Solution Algorithms and Shock-Dominated Applications
… multiphase fluid-material interaction problems. The first part of this dissertation is motivated by the extraordinary shock-resisting ability of elastomer coating materials (e.g., polyurea) under explosive loading conditions. Their performance, however, highly depends on their dynamic …
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On the formation of Friedlander waves in a compressed gas driven shock tube
… tests. The well-known initial structure of the Riemann problem eventually evolves into a shock structure resembling a Friedlander wave. In this thesis, we develop an analytical model to predict its key characteristics: location where the wave first forms, peak over-pressure, decay time and …
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Macroscopic Coupling Conditions with Partial Blocking for Highway Ramps
… modeled by an ODE. We define the solution to the Riemann problem at the junction using the supply and demand functions. The numerical approximation is carried out using a modified Godunov scheme, adjusted to take into account the effects of an emptying queue. Exact and numerical comparisons of the …
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Logaritminės eilės begalinio indekso nehomogeninis kraštinis Rymano uždavinys sričiai, apribotai begaliniu Dini – Lipšico kontūru /
In this work is formulated and studied boundary Riemann problem of logarithmic order α≥1 for the space bounded by the infinite Dini – Lipschitz contour. In this paper is used asymptotics of Cauchy type integrals with a logarithmic density. Basically differ functions Фα(z) and Фα*(z). In the first …
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Theoretical and numerical aspects of advection-pressure splitting for 1D blood flow models
… numerical methods for discretizing the ensuing problems. This study is inspired by the original flux splitting approach of Toro and Vázquez-Cendón (2012) originally developed for the conservative Euler equations of compressible gas dynamics. In this approach the flux vector in the conservative …
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Two-phase modelling of debris flow over composite topography: theoretical and numerical aspects
… flow events can produce serious problems to the population with possible casualties. On the other hand, the majority of these problems could be overcome with accurate hazard mapping, disaster prevention planning and mitigation structures (e.g. silt check dams, paved channels, …
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High resolution algorithms for the Navier Stokes equations for generalized descretizations
… interface states needed for the solution of a Riemann problem. The third reconstruction is used to evaluate the viscous fluxes. The gradient terms that appear in the viscous fluxes are formed by simply differentiating the polynomial. By selecting the appropriate cell control volumes, centered, …
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Large Time Step and Overlapping Grids for Conservation Laws
… method we propose here addresses both of these problems. We prove approximate solutions obtained are stable, and when convergent will always converge to a weak solution, regardless of relative grid cell sizes. Overlapping grids arise often in practice in order to discretized very complicated …
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Simulation of suspended sediment and contaminant transport in shallow water using two-dimensional depth-averaged model with unstructured meshes
… global populations and human activities, the problems of sediment transport and environmental hydraulics have been becoming more and more important and valued. Computational fluid dynamics is a very useful and powerful tool in those studies. In 2008, Dr. Liu developed a two-dimensional model …
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Chemical and Thermochemical Wave Behavior in Multiphase Fluid Flow Through Permeable Media: Wave-Wave Interactions
… of a nature not previously found under constant (Riemann) boundary conditions are formed. Through the nondimensionalization of the chemical-energy balance, we define six dimensionless parameters, and investigate the relative effects of these parameters on temperature and composition. One …
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A holistic multi-scale mathematical model of the murine extracellular fluid systems and study of the brain interactive dynamics
… new implicit solver for the junction-generalized Riemann problem. The resulting ADER scheme can deal with stiff source terms and can be applied to non-linear systems of hyperbolic balance laws in domains consisting of networks of one-dimensional sub-domains. Also, we design a novel one-dimensional …
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Long-term management and condition assessment of concrete culvert
… First, shock speed was studied by solving the Riemann Problem. After the piston stops, rarefaction will be generated and its speed is much faster than the shock. The interaction of rarefaction waves with shock waves was studied. The results show that when the rarefaction hits the shock, the …
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On the simulation and modeling for the reaction mechanism and solid state detonation phenomena in non-conventional explosives
… of numerical methods, including approximate Riemann solver, splitting method, higher-order interpolation and vacuum tracking method combined with the general equations of state. Our scheme can used for calculating TOA (Time of Arrival) of particles to the sensors in TOFMS and for …
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Multi-physics Diffuse Interface Methods For Computational Material Modelling
This thesis develops a novel numerical method for computational material modelling that is capable of incorporating a broad range of different materials and physical processes. Specifically, this work uses an Eulerian finite-volume diffuse interface scheme to examine high-Mach-number flows in a …
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Hadron production within a full transport approach with Statistical Hadronization Mechanism in Ultra-Relativistic Heavy Ion Collisions
La materia fortemente interagente è attualmente descritta, a livello fondamentale, dalla Cromodinamica Quantistica (QCD), che è parte del Modello Standard della fisica delle particelle. La teoria descrive l'interazione tra i quark come mediata dai gluoni e possiede due proprietà principali: la …