Evaluation de l'efficacité de blindage de parois hétérogènes par une méthode de Galerkin discontinue en domaine temporel

in Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC2012) (2012, July)

Optimizing the PML in the discrete context

Scientific conference (2012, March 30)

Perfectly Matched Layers (PML) are widely used for the simulation of unbounded wave-like problems. However their performance depends critically on both an absorption coefficient and the spatial ... [more ▼]

Perfectly Matched Layers (PML) are widely used for the simulation of unbounded wave-like problems. However their performance depends critically on both an absorption coefficient and the spatial discretization. Tuning the coefficient requires a costly (and case-dependent) optimization procedures... so that in most applications it is set empirically. In this talk we discuss the influence of the absorption coefficient on the PML performance for time-domain simulations, in both continuous and discrete contexts. We present efficient coefficients that allow to avoid any tuning in discrete contexts, and compare those with other frequent choices by means of benchmarks solved with both finite differences and finite elements (continuous and discontinuous). A realistic 3D discontinuous Galerkin benchmark for Maxwell's equations will highlight the advantages of our approach. [less ▲]

Optimization of the PML in the Discrete Context for Wave-Like Problems

Conference (2011, July 18)

The Perfectly Matched Layer (PML) is widely used for unbounded problems. However its performances depend critically on both an absorption coefficient and the numerical method. The coefficient is generally ... [more ▼]

The Perfectly Matched Layer (PML) is widely used for unbounded problems. However its performances depend critically on both an absorption coefficient and the numerical method. The coefficient is generally tuned by using optimization procedures. In this talk we will present some efficient profiles of the coefficient that overcome every tuning in discrete contexts. These profiles and others will be compared by using benchmarks with different numerical methods. [less ▲]

On the parameters of absorbing layers for shallow water models

in Ocean Dynamics (2010), 60(1), 65-79

Absorbing/sponge layers used as boundary conditions for ocean/marine models are examined in the context of the shallow water equations with the aim to minimize the reflection of outgoing waves at the ... [more ▼]

Absorbing/sponge layers used as boundary conditions for ocean/marine models are examined in the context of the shallow water equations with the aim to minimize the reflection of outgoing waves at the boundary of the computationaldomain. The ptimization of the absorption coefficient is not an issue in continuous models, for the reflection coefficient of outgoing waves can then be made as small as we please by increasing the absorption coefficient. The optimization of the parameters of absorbing layers is therefore a purely discrete problem. A balance must be found between the efficient damping of outgoing waves and the limited spatial resolution with which the resulting spatial gradients must be described. Using a one-dimensional model as a test case, the performances of various spatial distributions of the absorption coefficient are compared. Two shifted hyperbolic distributions of the absorption coefficient are derived from theoretical considerations for a pure propagative and a pure advective problems. These distribution show good performances. Their free parameter has a well-defined interpretation and can therefore be determined on a physical basis. The properties of the two shifted hyperbolas are illustrated using the classical two-dimensional problems of the collapse of a Gaussianshaped mound of water and of its advection by a mean current. The good behavior of the resulting boundary scheme remains when a full non-linear dynamics is taken into account. [less ▲]