All a b c d e f g h i j k l m n o p q r s t u v w x y z Other

Previous Page 104 Next

Displaying 2061 – 2080 of 2188

Showing per page

Uniformly stable mixed hp-finite elements on multilevel adaptive grids with hanging nodes

Friedhelm Schieweck (2008)

ESAIM: Mathematical Modelling and Numerical Analysis

We consider a family of quadrilateral or hexahedral mixed hp-finite elements for an incompressible flow problem with Qr-elements for the velocity and discontinuous P r - 1 -elements for the pressure where the order r can vary from element to element between 2 and an arbitrary bound. For multilevel adaptive grids with hanging nodes and a sufficiently small mesh size, we prove the inf-sup condition uniformly with respect to the mesh size and the polynomial degree.

Unique solvability and stability analysis of a generalized particle method for a Poisson equation in discrete Sobolev norms

Yusuke Imoto (2019)

Applications of Mathematics

Unique solvability and stability analysis is conducted for a generalized particle method for a Poisson equation with a source term given in divergence form. The generalized particle method is a numerical method for partial differential equations categorized into meshfree particle methods and generally indicates conventional particle methods such as smoothed particle hydrodynamics and moving particle semi-implicit methods. Unique solvability is derived for the generalized particle method for the...

Usage of modular scissors in the implementation of FEM

Frydrych, Dalibor (2010)

Programs and Algorithms of Numerical Mathematics

Finite Element Method (FEM) is often perceived as a unique and compact programming subject. Despite the fact that many FEM implementations mention the Object Oriented Approach (OOA), this approach is used completely, only in minority of cases in most real-life situations. For example, one of building stones of OOA, the interface-based polymorphism, is used only rarely. This article is focusing on the design reuse and at the same time it gives a complex view on FEM. The article defines basic principles...

Using successive approximations for improving the convergence of GMRES method

Jan Zítko (1998)

Applications of Mathematics

In this paper, our attention is concentrated on the GMRES method for the solution of the system ( I - T ) x = b of linear algebraic equations with a nonsymmetric matrix. We perform m pre-iterations y l + 1 = T y l + b before starting GMRES and put y m for the initial approximation in GMRES. We derive an upper estimate for the norm of the error vector in dependence on the m th powers of eigenvalues of the matrix T . Further we study under what eigenvalues lay-out this upper estimate is the best one. The estimate shows and numerical...

Validation of numerical simulations of a simple immersed boundary solver for fluid flow in branching channels

Keslerová, Radka, Lancmanová, Anna, Bodnár, Tomáš (2023)

Programs and Algorithms of Numerical Mathematics

This work deals with the flow of incompressible viscous fluids in a two-dimensional branching channel. Using the immersed boundary method, a new finite difference solver was developed to interpret the channel geometry. The numerical results obtained by this new solver are compared with the numerical simulations of the older finite volume method code and with the results obtained with OpenFOAM. The aim of this work is to verify whether the immersed boundary method is suitable for fluid flow in channels...

Variational approximation of flux in conforming finite element methods for elliptic partial differential equations : a model problem

Franco Brezzi, Thomas J. R. Hughes, Endre Süli (2001)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

We consider the approximation of elliptic boundary value problems by conforming finite element methods. A model problem, the Poisson equation with Dirichlet boundary conditions, is used to examine the convergence behavior of flux defined on an internal boundary which splits the domain in two. A variational definition of flux, designed to satisfy local conservation laws, is shown to lead to improved rates of convergence.

Variational characterization of eigenvalues of a non-symmetric eigenvalue problem governing elastoacoustic vibrations

Markus Stammberger, Heinrich Voss (2014)

Applications of Mathematics

Small amplitude vibrations of an elastic structure completely filled by a fluid are considered. Describing the structure by displacements and the fluid by its pressure field one arrives at a non-selfadjoint eigenvalue problem. Taking advantage of a Rayleigh functional we prove that its eigenvalues can be characterized by variational principles of Rayleigh, minmax and maxmin type.

Variational problems in domains with cusp points

Alexander Ženíšek (1993)

Applications of Mathematics

The finite element analysis of linear elliptic problems in two-dimensional domains with cusp points (turning points) is presented. This analysis needs on one side a generalization of results concerning the existence and uniqueness of the solution of a constinuous elliptic variational problem in a domain the boundary of which is Lipschitz continuous and on the other side a presentation of a new finite element interpolation theorem and other new devices.

Variational sensitivity analysis of parametric Markovian market models

Norbert Hilber, Christoph Schwab, Christoph Winter (2008)

Banach Center Publications

Parameter sensitivities of prices for derivative contracts play an important role in model calibration as well as in quantification of model risk. In this paper a unified approach to the efficient numerical computation of all sensitivities for Markovian market models is presented. Variational approximations of the integro-differential equations corresponding to the infinitesimal generators of the market model differentiated with respect to the model parameters are employed. Superconvergent approximations...

Viscous Shock Capturing in a Time-Explicit Discontinuous Galerkin Method

A. Klöckner, T. Warburton, J. S. Hesthaven (2011)

Mathematical Modelling of Natural Phenomena

We present a novel, cell-local shock detector for use with discontinuous Galerkin (DG) methods. The output of this detector is a reliably scaled, element-wise smoothness estimate which is suited as a control input to a shock capture mechanism. Using an artificial viscosity in the latter role, we obtain a DG scheme for the numerical solution of nonlinear systems of conservation laws. Building on work by Persson and Peraire, we thoroughly justify the...

Currently displaying 2061 – 2080 of 2188