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Marc Bonnet (ENSTA)04/02/2016 09:15In contrast with the vast existing literature on the mathematical aspects of boundary integral equations and their application to scattering by impenetrable obstacles characterized by Dirichlet, Neumann or impedant boundary conditions, comparatively few studies are available regarding the mathematical properties of volume integral equation (VIE) formulations. This communication addresses the...Aller à la page de la contribution
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Guillaume Sylvand (Airbus Group)04/02/2016 09:50For the numerical simulation of wave propagation in acoustics, Airbus Group Innovations relies on integral equations solved with the Boundary Elements Method. The advantages of this approach are well known: mainly accuracy, and simpler (surfacic) mesh. The main algorithm drawback is the need to cope with a dense matrix whose size can be quite large for wave propagation problems, where the...Aller à la page de la contribution
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Xavier Claeys (UPMC)04/02/2016 10:45In the context of time harmonic wave scattering by piecewise homogeneous penetrable objects, we present a new variant of the multi-trace boundary integral formulations (MTF). This new approach differs from the so-called "local" MTF by the presence of regularisation terms involving boundary integral operators and localised at junctions i.e. points where at least three subdomains abut. It lends...Aller à la page de la contribution
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Jérôme Simon (Onera Palaiseau)04/02/2016 11:20The Surface Integral Equation is one of the most used methods in the simulation of electromagnetic problems. Its implementation combined with a fast multipole algorithm (MLFMM) and iterative solvers leads efficient and accurate methods for the analysis of radar cross section (RCS) for a target.
Different methods (MLFMM, ACA, Domain Decomposition Method …) and formulations EFIE... Aller à la page de la contribution -
Christophe Geuzaine (Université de Liège)04/02/2016 11:55In terms of computational methods, solving three-dimensional time-harmonic acoustic or electromagnetic wave problems is known to be challenging, especially in the high frequency regime and in the presence of inhomogenous media. The brute-force application of the finite element method in this case leads to the solution of very large, complex and possibly indefinite linear systems....Aller à la page de la contribution
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Jean-Claude Nédélec (Ecole Polytechnique)04/02/2016 14:15
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Marion Darbas (Université de Picardie)04/02/2016 14:50The numerical solution of time-harmonic scattering problems remains challenging in the high frequency regime due to its specific computational bottlenecks. The techniques based on integral equations lead to the resolution of linear systems where the involved matrices are dense and usually badly conditioned. The improvement of these methods is a timely research area. One possibility to reduce...Aller à la page de la contribution
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Stephen Langdon (University of Reading)04/02/2016 15:25Linear wave scattering problems (e.g. for acoustic, electromagnetic and elastic waves) are ubiquitous in science and engineering applications. However, conventional numerical methods for such problems (e.g. FEM or BEM with piecewise polynomial basis functions) are prohibitively expensive when the wavelength of the scattered wave is small compared to typical lengthscales of the scatterer (the...Aller à la page de la contribution
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Catalin Turc (New Jersey Institute of Technology)04/02/2016 16:20We present a new Windowed Green Function (WGF) method for the numerical integral-equation solution of problems of electromagnetic scattering by obstacles in presence of dielectric or conducting half-planes. The WGF method, which is based on use of integral kernels that can be expressed directly in terms of the free-space Green function, does not require evaluation of expensive Sommerfeld...Aller à la page de la contribution
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Matthieu Aussal (Ecole Polytechnique)04/02/2016 16:55Fast convolution on unstructured grids have been developed for many applications (e.g. electrostatics, magnetostatics, acoustics, electro- magnetics, etc.). The goal is to reduce the complexity of matrix-vector products, from O(N^2) to O(N log N ). In this presentation, we describe a new efficient numerical method called Sparse Cardinal Sine Decomposition (SCSD), based on a suitable...Aller à la page de la contribution
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Simon N. Chandler-Wilde (University of Reading)05/02/2016 09:00In this talk we discuss the application of the unified transform method, due to A.S. Fokas and co-authors, to interior and exterior problems for time harmonic waves. Like integral equation methods, the method reduces to the solution of a problem on the boundary of the domain in question. We discuss numerical implementations, restricting the solution space to a finite-dimensional subspace, and...Aller à la page de la contribution
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Paul Soudais (Dassault Aviation)05/02/2016 09:35Impedance Boundary Conditions (IBC) are widely used in computational electromagnetics to model thin coatings on perfectly conducting (PEC) objects. The IBC is used to reduce drastically the number of unknowns of the integral equations models and to obtain a better conditioned linear system that can be more efficiently iteratively solved.
Integral equations models can be built that... Aller à la page de la contribution -
Marc Bakry, Sébastien Pernet (Onera Toulouse)05/02/2016 10:10A posteriori error estimates are tools which enable a measure of the numerical error. They are required to be equivalent to the norm of the error and to be locally computable. They are norms of values which can be computed from the numerical solution and the problem parameters. In the context of BEM, there is a loss of locality of the norms and therefore of the estimates. Standard localization...Aller à la page de la contribution
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Edouard Demaldent (CEA)05/02/2016 11:05Electromagnetic testing is widely used for the characterization of a medium as to the detection of defects. In particular, the eddy current non-destructive testing of tubes in steam generators is determinant to diagnose the integrity of heat exchangers in nuclear industry. A valuable support to the mastering of these processes is brought by modeling and the finite boundary element method (BEM)...Aller à la page de la contribution
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Abderrahmane Bendali (INSA Toulouse)05/02/2016 11:40We first briefly present the dispersion phenomenon and show how it damages the numerical solution of wave problems over large distances of propagation. We then introduce a Trefftz Discontinuous Galerkin (TDG) symmetric formulation for the Helmholtz equation with piecewise constant coefficients. Recall that Trefftz methods are discretization processes based on the use of exact interior either...Aller à la page de la contribution
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Ralf Hiptmair (ETH Zürich)05/02/2016 14:00For second-order linear transmission problems involving a single closed interface separating two homogeneous materials, a well-posed second-kind boundary integral formulation has been known for a long time. It arises from a straightforward combination of interior and exterior Calderon identities. Apparently, this simple approach cannot be extended to "composite" settings involving more than...Aller à la page de la contribution
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Toufic Abboud (IMACS)05/02/2016 14:35Electromagnetic Compatibility (EMC) modelling is a major issue in aeronautic industry, with applications like Lightning Indirect Effects, High-Intensity Radiated Fields, antenna coupling, wifi… These simulations represent many challenges for the numerical solvers: very large frequency band (starting from DC), need for local models (wires, slots, equipment…), low levels of currents and fields...Aller à la page de la contribution
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Francesco Andriulli (Télécom Bretagne)05/02/2016 15:10Integral equation solvers are widely used for simulating electromagnetic scattering and radiation from metallic and penetrable objects. Long popular in academic circles, these solvers have been in recent years incorporated into several commercial electromagnetic analysis and design tools, after the advent of fast multipole and related algorithms. The effectiveness of these solvers...Aller à la page de la contribution
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Prof. Olaf Steinbach05/02/2016 16:05In this talk we consider direct and indirect boundary integral formulations for the solution of electro– and magnetostatic field computations in industrial applications. Particular interest is on the use of floating potentials in a multi–dielectric setting with high permittivity.
This talk summarizes joint work with A. Blaszczyk and Z. Andjelic (ABB), and with D. Amann, G. Of, and... Aller à la page de la contribution -
Dr Stéphanie Chaillat05/02/2016 16:40The main advantage of the Boundary Element Method (BEM) is that only the domain boundaries are discretized leading to a drastic reduction of the total number of degrees of freedom.
In traditional BE implementation the dimensional advantage with respect to domain discretization methods is offset by the fully-populated nature of the BEM coefficient matrix. In the present work, we... Aller à la page de la contribution
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