Results 1-20 of 292. Search equation: ((author:geuzaine) AND (author:christophe)) Sort: Author Title Issue date Filter: All documents types Scientific journals - Article - Short communication - Book review - Letter to the editor - Complete issue - OtherBooks - Book published as author, translator, etc. - Collective work published as editor or directorParts of books - Contribution to collective works - Contribution to encyclopedias, dictionaries... - Preface, postface, glossary...Scientific congresses and symposiums - Unpublished conference - Paper published in a book - Paper published in a journal - PosterScientific conference in universities or research centersReports - Expert report - Internal report - External report - OtherDissertations and theses - Master of advanced studies dissertation - Master's dissertation - Doctoral thesis - Post doctoral thesisLearning materials - Course notes - OtherPatentCartographic materials - Single work - Part of another publicationComputer developments - Textual, factual or bibliographical database - Software - OtherE-prints/Working papers - First made available on ORBi - Already available on another siteDiverses speeches and writings - Article for general public - Conference given outside the academic context - Speech - Other     Geometrical Validity of Curvilinear Finite ElementsJohnen, Amaury ; Remacle, J.-F.; Geuzaine, Christophe in Journal of Computational Physics (in press)In this paper, we describe a way to compute accurate bounds on Jacobian de- terminants of curvilinear polynomial finite elements. Our condition enables to guarantee that an element is geometrically valid ... [more ▼]In this paper, we describe a way to compute accurate bounds on Jacobian de- terminants of curvilinear polynomial finite elements. Our condition enables to guarantee that an element is geometrically valid, i.e., that its Jacobian determinant is strictly positive everywhere in its reference domain. It also provides an efficient way to measure the distortion of curvilinear elements. The key feature of the method is to expand the Jacobian determinant using a polynomial basis, built using B ́ezier functions, that has both properties of boundedness and positivity. Numerical results show the sharpness of our estimates. [less ▲]Detailed reference viewed: 63 (16 ULg) Geometrical Validity of High-Order Triangular Finite ElementsJohnen, Amaury ; Remacle, Jean-François; Geuzaine, Christophe in Engineering with Computers (in press)This paper presents a method to compute accurate bounds on Jacobian determinants of high-order (curvilinear) triangular nite elements. This method can be used to guarantee that a curvilinear triangle is ... [more ▼]This paper presents a method to compute accurate bounds on Jacobian determinants of high-order (curvilinear) triangular nite elements. This method can be used to guarantee that a curvilinear triangle is geometrically valid, i.e., that its Jacobian determinant is strictly positive everywhere in its reference domain. It also provides an e cient way to measure the quality the triangles. The key feature of the method is to expand the Jacobian determinant using a polynomial basis, built using B ezier functions, that has both properties of boundedness and positivity. Numerical results show the sharpness of our estimates. [less ▲]Detailed reference viewed: 64 (10 ULg) A Frontal Delaunay Quad Mesh Generator Using the L ∞  NormRemacle, J.-F.; Henrotte, F.; Carrier-Baudouin, T. et alin International Journal for Numerical Methods in Engineering (in press)Detailed reference viewed: 53 (12 ULg) An Energy-Based Variational Model of Ferromagnetic Hysteresis for Finite Element ComputationsFrançois-Lavet, Vincent; Henrotte, François; Stainier, Laurent et alin Journal of Computational & Applied Mathematics (2013), 246This paper proposes a macroscopic model for ferromagnetic hysteresis that is well-suited for finite element implementation. The model is readily vectorial and relies on a consistent thermodynamic ... [more ▼]This paper proposes a macroscopic model for ferromagnetic hysteresis that is well-suited for finite element implementation. The model is readily vectorial and relies on a consistent thermodynamic formulation. In particular, the stored magnetic energy and the dissipated energy are known at all times, and not solely after the completion of closed hysteresis loops as is usually the case. The obtained incremental formulation is variationally consistent, i.e., all internal variables follow from the minimization of a thermodynamic potential. [less ▲]Detailed reference viewed: 84 (22 ULg) Fifth International Conference on Advanced COmputational Methods in ENgineering (ACOMEN 2011)Béchet, Eric ; Dick, Erik; Geuzaine, Christophe et alin International Journal of Computational & Applied Mathematics (2013), 246Detailed reference viewed: 19 (8 ULg) Computational Homogenization for Laminated Ferromagnetic Cores in MagnetodynamicsNiyonzima, Innocent ; V Sabariego, Ruth; Dular, Patrick et alin IEEE Transactions on Magnetics (2013), 49(5), 2049-2052In this paper, we investigate the modeling of ferromagnetic multiscale materials. We propose a computational homogenization technique based on the heterogeneous multiscale method (HMM) that includes both ... [more ▼]In this paper, we investigate the modeling of ferromagnetic multiscale materials. We propose a computational homogenization technique based on the heterogeneous multiscale method (HMM) that includes both eddy-current and hysteretic losses at the mesoscale. The HMM comprises: 1) a macroscale problem that captures the slow variations of the overall solution; 2) many mesoscale problems that allow to determine the constitutive law at the macroscale. As application example, a laminated iron core is considered. [less ▲]Detailed reference viewed: 26 (2 ULg) A Computational Homogenization Method for the Evaluation of Eddy Current in Nonlinear Soft Magnetic CompositesNiyonzima, Innocent ; Vazquez Sabariego, Ruth ; Dular, Patrick et alin Proceeding of the 9th International Symposium on Electric and Magnetic Fields, EMF 2013 (2013, April 23)The use of the soft magnetic composite (SMC) in electric devices has increased in recent years. These materials made from a metallic powder compacted with a dielectric binder are a good alternative to ... [more ▼]The use of the soft magnetic composite (SMC) in electric devices has increased in recent years. These materials made from a metallic powder compacted with a dielectric binder are a good alternative to laminated ferromagnetic structures as their granular mesoscale structure allows to significantly reduce the eddy current losses. Furthermore unlike the laminated ferromagnetic structures, SMC exhibit isotropic magnetic properties what makes them good candidates for manufacturing machines with 3D flux paths. The isotropy of the thermal conductivity also allows for a more efficient heat dissipation. The use of classical numerical methods such as the finite element method to study the behavior of SMC is computational very expensive. Indeed a very fine mesh would be required in order to capture fine scale variations i.e. variations at level of metallic grains whence the use of multiscale methods for modelling SMC. The application of multiscale method to study the behaviour of SMC is relatively recent. In (A. Bordianu et al “A Multiscale Approach to Predict Classical Losses in Soft Magnetic Composites”, IEEE Trans. Mag., vol. 48, no. 4, 2012.), the authors used a homogenization technique to compute electrical and magnetic constitutive laws on a representative volume element (RVE). These laws were then used in finite element computations. Herein, the RVE has been chosen to account for the grain- grain contact that can occur in a actual SMC structure due to the compaction process and that can lead to the appearance of macroscale eddy currents. In this paper, we will extend the computational homogenization method success- fully used for modelling the behaviour of laminated ferromagnetic cores in mag- netodynamics (I. Niyonzima et al “Computational Homogenization for Laminated Ferromagnetic Cores in Magnetodynamics”, in Proc. of the 15th Biennal Confer- ence on Electromagnetic Field Computation, 2012) to the case of SMC. The method is based on the heterogeneous multiscale method (HMM) and couples two types of problems: a macroscale problem that captures the slow variations of the overall so- lution and many microscale problems that allow to determine the constitutive laws at the macroscale. The choice of RVE will also be discussed. [less ▲]Detailed reference viewed: 45 (8 ULg) Subproblem h-Conform Formulation for Accurate Thin Shell Models Between Conducting and Nonconducting RegionsDang, Quoc Vuong ; Dular, Patrick ; Vazquez Sabariego, Ruth et alin Proceeding of the 9th International Symposium on Electric and Magnetic Fields, EMF 2013 (2013, April 23)A subproblem method (SPM) with h-formulation is developed for correcting the inaccuracies near edges and corners that arise from using thin shell (TS) models to replace thin volume regions by surfaces ... [more ▼]A subproblem method (SPM) with h-formulation is developed for correcting the inaccuracies near edges and corners that arise from using thin shell (TS) models to replace thin volume regions by surfaces. The developed surface-to-volume correction problem is defined as a step of multiple SPs, with inductors and magnetic or conducting regions, some of them being thin. The TS model assumes that the fields in the thin regions are approximated by a priori 1-D analytical distributions along the shell thickness (C. Geuzaine et al., “Dual formulations for the modeling of thin electromagnetic shells using edge elements,” IEEE Trans. Magn., vol. 36, no. 4, pp. 799–802, 2000). Their interior is not meshed and ratherextracted from the studied domain, which is reduced to a zero-thickness double layer with interface conditions (ICs) linked to 1-D analytical distributions that however neglect end and curvature effects. This leads to inaccuracies near edges and corners that increase with the thickness. To cope with these difficulties, the authors have recently proposed a SPM based on the h-formulation for a thin region located between non-conducting regions (Vuong Q. Dang et al., “Subproblem Approach for Thin Shell Dual Finite Element Formulations”, IEEE Trans. Magn., vol. 48, no. 2, pp. 407–410, 2012). The magnetic field h is herein defined in nonconducting regions by means of a magnetic scalar potential , i.e. h = -grad{\phi} , with discontinuities of through the TS. In this paper, the SPM is extended to account for thin regions located between conducting regions or between conducting and nonconducting regions, in the general case of multiply connected regions. In these regions, the potential is not defined anymore on both sides of the TS and the problem has to be expressed in terms of the discontinuities of h, possibly involving on one side only, to be strongly defined via an IC through the TS. In the proposed SP strategy, a reduced problem with only inductors is first solved on a simplified mesh without thin and volume regions. Its solution gives surface sources (SSs) as ICs for added TS regions, and volume sources (VSs) for possible added volume regions. The TS solution is further improved by a volume correction via SSs and VSs that overcome the TS assumptions, respectively suppressing the TS model and adding the volume model. Each SP has its own separate mesh, which increases the computational efficiency. Details on the proposed method will be given in the extended paper, with practical applications. [less ▲]Detailed reference viewed: 26 (3 ULg) Dual Formulations for Accurate Thin Shell Models in a Finite Element Subproblem MethodDang, Quoc Vuong ; Dular, Patrick ; Vazquez Sabariego, Ruth et alin Proceeding of the 19th COMPUMAG Conference on the Computation of Electromagnetic Fields, 2013 (2013, April 01)A subproblem finite with dual finite element magnetostatic and magnetodynamic formulations is developed for correcting the inaccuracies near edges and corners coming from thin shell models, that replace ... [more ▼]A subproblem finite with dual finite element magnetostatic and magnetodynamic formulations is developed for correcting the inaccuracies near edges and corners coming from thin shell models, that replace thin volume regions by surfaces. The surface-to-volume correction problem is defined as one of the multiple subproblems applied to a complete problem, considering successive additions of inductors and magnetic or conducting regions, some of these being thin regions. Each SP requires a proper adapted mesh of its regions, which facilitates meshing and increases computational e ciency. [less ▲]Detailed reference viewed: 21 (3 ULg) Homogenisation of Windings and Laminations in Time-Domain Finite-Element Modeling of Electrical MachinesGyselinck, Johan; Geuzaine, Christophe ; Vazquez Sabariego, Ruth in Proceedings of the 15th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2012) (2012, November)This paper deals with time-domain homogenisation of multi-turn windings and laminated cores in 2D and 3D finite- element (FE) modelling of rotating electrical machines. Herein the number of additional ... [more ▼]This paper deals with time-domain homogenisation of multi-turn windings and laminated cores in 2D and 3D finite- element (FE) modelling of rotating electrical machines. Herein the number of additional degrees of freedom (auxiliary field variables) in the homogenised regions can be fixed depending on the extent of the eddy current effects and on the desired accuracy. The homogenisation technique is illustrated and validated by means of a 2D model of a switched reluctance motor. Global quantities, such as the phase impedance, converge very well to those produced by a precise but very expensive 3D model. [less ▲]Detailed reference viewed: 36 (4 ULg) Computational Homogenization for Laminated Ferromagnetic Cores in MagnetodynamicsNiyonzima, Innocent ; Vazquez Sabariego, Ruth ; Henrotte, François et alin Proceedings of the 15th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2012) (2012, November)In this paper, we investigate the modeling of fer- romagnetic multiscale materials. We propose a computational homogenization method based on the heterogeneous multiscale method (HMM) that includes eddy ... [more ▼]In this paper, we investigate the modeling of fer- romagnetic multiscale materials. We propose a computational homogenization method based on the heterogeneous multiscale method (HMM) that includes eddy currents and hysteretic losses at the mesoscale. The HMM comprises: 1) a macroscale problem that captures the slow variations of the overall solution; 2) many microscale problems that allow to determine the constitutive law at the macroscale. As application example, a laminated iron core is considered. [less ▲]Detailed reference viewed: 65 (14 ULg) Time-domain finite-element modelling of laminated iron cores – Large skin effect homogenization considering the Jiles-Atherton hysteresis modelVazquez Sabariego, Ruth ; Niyonzima, Innocent ; Geuzaine, Christophe et alin Proceedings of the 15th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2012) (2012, November)This paper deals with the incorporation of the Jiles- Atherton (J-A) hysteresis model in a time-domain finite-element homogenization technique for laminated iron cores. The separate discretization of each ... [more ▼]This paper deals with the incorporation of the Jiles- Atherton (J-A) hysteresis model in a time-domain finite-element homogenization technique for laminated iron cores. The separate discretization of each lamination is avoided by using dedicated skin-effect basis functions, which also serve to interpolate the J- A hysteretic material law. As validation test case, a stacked ring core surrounded by a toroidal coil is considered. [less ▲]Detailed reference viewed: 42 (6 ULg) An optimum PML for scattering problems in time-domainModave, Axel ; Delhez, Eric ; Kameni, Abelin et alin Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC2012) (2012, July 05)The Perfectly Matched Layer (PML) is widely used for unbounded problems. However its performances depend critically on an absorption coefficient. This coefficient is generally tuned by using case ... [more ▼]The Perfectly Matched Layer (PML) is widely used for unbounded problems. However its performances depend critically on an absorption coefficient. This coefficient is generally tuned by using case-dependent optimization procedures. In this paper we will present some efficient profiles of the coefficient that overcome every tuning. These profiles and others will be compared by using a scattering benchmark solved with the Discontinuous Galerkin method. [less ▲]Detailed reference viewed: 42 (11 ULg) Multiscale Quasistatic Homogenization for Laminated Ferromagnetic CoresNiyonzima, Innocent ; Vazquez Sabariego, Ruth ; Dular, Patrick et alin Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC 2012) (2012, July 03)In this paper, we investigate the modeling of ferromagnetic multiscale materials. We propose a computational homogenization method based on the heterogeneous multiscale method (HMM) with inclusion of a ... [more ▼]In this paper, we investigate the modeling of ferromagnetic multiscale materials. We propose a computational homogenization method based on the heterogeneous multiscale method (HMM) with inclusion of a hysteresis model. The HMM involves: 1) a macroscale problem that captures the slow variations of the overall solution; 2) many microscale problems that allow to determine the constitutive law at the macroscale. At the microscale, a novel energy consistent hystere- sis model is incorporated. As application example, a laminated iron core is considered. [less ▲]Detailed reference viewed: 67 (19 ULg) Subproblem h-Conform Magnetodynamic Finite Element Formulation for Accurate Model of Multiply Connected Thin RegionsDang, Quoc Vuong ; Dular, Patrick ; Vazquez Sabariego, Ruth et alin Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC 2012) (2012, July 03)A subproblem $\vh$-conform eddy current finite element method is proposed for correcting the inaccuracies inherent to thin shell models. Such models replace volume thin regions by surfaces but neglect ... [more ▼]A subproblem $\vh$-conform eddy current finite element method is proposed for correcting the inaccuracies inherent to thin shell models. Such models replace volume thin regions by surfaces but neglect border effects in the vicinity of their edges and corners. The developed surface-to-volume correction problem is defined as a step of the multiple subproblems applied to a complete problem, consisting of inductors and magnetic or conducting regions, some of these being thin regions. The general case of multiply connected thin regions is considered. [less ▲]Detailed reference viewed: 40 (17 ULg) Evaluation de l'efficacité de blindage de parois hétérogènes par une méthode de Galerkin discontinue en domaine temporelKameni, A.; Modave, Axel ; Boubekeur, M. et alin Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC2012) (2012, July)Detailed reference viewed: 24 (6 ULg) A dynamical model with hysteresis for the homogenization of ferromagnetic laminated coresHenrotte, F.; Niyonzima, Innocent ; Steentjes, S. et alin Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC2012) (2012, July)Detailed reference viewed: 37 (11 ULg) ONELAB: Open Numerical Engineering LABoratoryGeuzaine, Christophe ; Henrotte, F.; Marchandise, E. et alin Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC2012) (2012, July)Detailed reference viewed: 63 (9 ULg) Le monde à l'envers : résoudre des EDPs pour construire des maillagesGeuzaine, Christophe Scientific conference (2012, June 05)Detailed reference viewed: 42 (2 ULg) Combining Full Transients and Phasor Approximation Models in Power System Time SimulationPlumier, Frédéric ; Fabozzi, Davide ; Geuzaine, Christophe et alin Proceedings of the 21th International Conference on Domain Decomposition Methods (DD21) (2012, June)Detailed reference viewed: 81 (19 ULg)