676 research outputs found

    Residual equilibrium schemes for time dependent partial differential equations

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    Many applications involve partial differential equations which admits nontrivial steady state solutions. The design of schemes which are able to describe correctly these equilibrium states may be challenging for numerical methods, in particular for high order ones. In this paper, inspired by micro-macro decomposition methods for kinetic equations, we present a class of schemes which are capable to preserve the steady state solution and achieve high order accuracy for a class of time dependent partial differential equations including nonlinear diffusion equations and kinetic equations. Extension to systems of conservation laws with source terms are also discussed.Comment: 23 pages, 12 figure

    Parallelization of a relaxation scheme modelling the bedload transport of sediments in shallow water flow

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    In this work we are interested in numerical simulations for bedload erosion processes. We present a relaxation solver that we apply to moving dunes test cases in one and two dimensions. In particular we retrieve the so-called anti-dune process that is well described in the experiments. In order to be able to run 2D test cases with reasonable CPU time, we also describe and apply a parallelization procedure by using domain decomposition based on the classical MPI library.Comment: 19 page

    Modelling Shallow Water Flows by a High Resolution Riemann Solver

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    Shock-capturing methods originally developed for compressible gas dynamics has been applied to many other non-linear hyperbolic systems of conservation equations, like reactive flows, two-phase flow, porous media flow and finally shallow water flows, with applications to rivers, estuaries, dam break and in particular tsunami propagation resulting from earthquake and landslide. The basic ingredient of the proposed model for solving the shallow water equations is a finite volume Flux Vector Splitting Riemann Solver with a second order resolution scheme and implicit treatment of the source terms. The model includes entropy fix and step bed treatments, and finally shore line tracking, giving the ability to capture local discontinuities - like shock waves - and reducing numerical diffusion and unphysical viscosity effects which dominates in all finite difference methods. The numerical model has been validated in respect to different numerical test cases and comparisons with the exact solution of the Riemann problems are presented.JRC.G.7-Traceability and vulnerability assessmen

    Well-balanced positivity preserving central-upwind scheme on triangular grids for the Saint-Venant system

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    We introduce a new second-order central-upwind scheme for the Saint-Venant system of shallow water equations on triangular grids. We prove that the scheme both preserves “lake at rest” steady states and guarantees the positivity of the computed fluid depth. Moreover, it can be applied to models with discontinuous bottom topography and irregular channel widths. We demonstrate these features of the new scheme, as well as its high resolution and robustness in a number of numerical examples

    ICASE/LaRC Workshop on Adaptive Grid Methods

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    Solution-adaptive grid techniques are essential to the attainment of practical, user friendly, computational fluid dynamics (CFD) applications. In this three-day workshop, experts gathered together to describe state-of-the-art methods in solution-adaptive grid refinement, analysis, and implementation; to assess the current practice; and to discuss future needs and directions for research. This was accomplished through a series of invited and contributed papers. The workshop focused on a set of two-dimensional test cases designed by the organizers to aid in assessing the current state of development of adaptive grid technology. In addition, a panel of experts from universities, industry, and government research laboratories discussed their views of needs and future directions in this field
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