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We solve acoustic scattering problems by means of the isogeometric boundary integral equation method. In order to avoid spurious modes, we apply the combined field integral equations for either sound-hard scatterers or sound-soft…

Numerical Analysis · Mathematics 2023-06-21 Jürgen Dölz , Helmut Harbrecht , Michael Multerer

We present a hybrid continuous and discontinuous Galerkin spectral element approximation that leverages the advantages of each approach. The continuous Galerkin approximation is used on interior element faces where the equation properties…

Numerical Analysis · Mathematics 2020-12-14 David A. Kopriva , Gregor J. Gassner

An elliptic partial differential equation Lu=f with a zero Dirichlet boundary condition is converted to an equivalent elliptic equation on the unit ball. A spectral Galerkin method is applied to the reformulated problem, using multivariate…

Numerical Analysis · Mathematics 2011-06-20 Kendall Atkinson , David Chien , Olaf Hansen

In this paper we propose an algorithm for the formation of matrices of isogeometric Galerkin methods. The algorithm is based on three ideas. The first is that we perform the external loop over the rows of the matrix. The second is that we…

Numerical Analysis · Mathematics 2017-04-05 Francesco Calabrò , Giancarlo Sangalli , Mattia Tani

In the frame of isogeometric analysis, we consider a Galerkin boundary element discretization of the hyper-singular integral equation associated with the 2D Laplacian. We propose and analyze an adaptive algorithm which locally refines the…

Numerical Analysis · Mathematics 2020-03-03 Gregor Gantner , Dirk Praetorius , Stefan Schimanko

Isogeometric analysis with the boundary element method (IGABEM) has recently gained interest. In this paper, the approximability of IGABEM on 3D acoustic scattering problems will be investigated and a new improved BeTSSi submarine will be…

Numerical Analysis · Mathematics 2022-04-21 Jon Vegard Venås , Trond Kvamsdal

This work extends the high-resolution isogeometric analysis approach established for scalar transport equations to the equations of gas dynamics. The group finite element formulation is adopted to obtain an efficient assembly procedure for…

Numerical Analysis · Mathematics 2018-10-01 Matthias Möller , Andrzej Jaeschke

The recent development of spectral method has been praised for its high-order convergence in simulating complex physical problems. The combination of embedded boundary method and spectral method becomes a mainstream way to tackle…

Numerical Analysis · Mathematics 2018-03-08 Po-Yi Wu , Cheng-Hong Robert Kao , Tony Wen-Hann Sheu

The isogeometric formulation of Boundary Element Method (BEM) is investigated within the adaptivity framework. Suitable weighted quadrature rules to evaluate integrals appearing in the Galerkin BEM formulation of 2D Laplace model problems…

Numerical Analysis · Mathematics 2022-05-06 Antonella Falini , Carlotta Giannelli , Tadej Kanduc , Maria Lucia Sampoli , Alessandra Sestini

A coupled hybridizable discontinuous Galerkin (HDG) and boundary integral (BI) method is proposed to efficiently analyze electromagnetic scattering from inhomogeneous/composite objects. The coupling between the HDG and the BI equations is…

Computational Engineering, Finance, and Science · Computer Science 2023-06-21 Ran Zhao , Ming Dong , Liang Chen , Jun Hu , Hakan Bagci

This thesis aims at investigating the first steps toward an unconditionally stable space-time isogeometric method, based on splines of maximal regularity, for the linear acoustic wave equation. The unconditional stability of space-time…

Numerical Analysis · Mathematics 2023-03-29 Sara Fraschini

Generalized Locally Toeplitz (GLT) matrix sequences arise from large linear systems that approximate Partial Differential Equations (PDEs), Fractional Differential Equations (FDEs), and Integro-Differential Equations (IDEs). GLT sequences…

Numerical Analysis · Mathematics 2024-07-25 V. B. Kiran Kumar , N. S. Sarathkumar

The polynomial spline collocation method is proposed for solution of Volterra integral equations of the first kind with special piecewise continuous kernels. The Gauss-type quadrature formula is used to approximate integrals during the…

Numerical Analysis · Mathematics 2021-11-24 A. Tynda , S. Noeiaghdam , D. Sidorov

In this paper, we develop a local multiscale model reduction strategy for the elastic wave equation in strongly heterogeneous media, which is achieved by solving the problem in a coarse mesh with multiscale basis functions. We use the…

Numerical Analysis · Mathematics 2022-07-12 Zhongqian Wang , Shubin Fu , Zishang Li , Eric Chung

Isogeometric approach applied to Boundary Element Methods is an emerging research area. In this context, the aim of the present contribution is that of investigating, from a numerical point of view, the Symmetric Galerkin Boundary Element…

Numerical Analysis · Mathematics 2022-04-07 A. Aimi , M. Diligenti , M. L. Sampoli , A. Sestini

The main goal of this thesis is to show the crucial role that plays the symbol in analysing the spectrum the sequence of matrices resulting from PDE approximation and in designing a fast method to solve the associated linear problem. In the…

Numerical Analysis · Mathematics 2022-06-13 Ryma Imene Rahla

In this paper, we develop multigrid solvers for the biharmonic problem in the framework of isogeometric analysis (IgA). In this framework, one typically sets up B-splines on the unit square or cube and transforms them to the domain of…

Numerical Analysis · Mathematics 2019-06-18 Jarle Sogn , Stefan Takacs

In this work we address the complexity problem of the isogeometric Boundary Element Method by proposing a collocation scheme for practical problems in linear elasticity and the application of hierarchical matrices. For mixed boundary value…

Numerical Analysis · Computer Science 2014-06-12 Jürgen Zechner , Benjamin Marussig , Gernot Beer , Thomas-Peter Fries

We propose a new discontinuous Galerkin Isogeometric Analysis (IgA) technique for the numerical solution of elliptic diffusion problems in computational domains decomposed into volumetric patches with non-matching interfaces. Due to an…

Numerical Analysis · Mathematics 2015-11-19 Christoph Hofer , Ulrich Langer , Ioannis Toulopoulos

We present W-cycle multigrid algorithms for the solution of the linear system of equations arising from a wide class of $hp$-version discontinuous Galerkin discretizations of elliptic problems. Starting from a classical framework in…

Numerical Analysis · Mathematics 2013-12-02 P. F. Antonietti , M. Sarti , M. Verani