Publications

2005

• AN ANALYSIS OF HIGHER ORDER BOUNDARY CONDITIONS FOR THE WAVE EQUATION
  
  • Diaz Julien
  • Joly Patrick
  SIAM Journal on Applied Mathematics, Society for Industrial and Applied Mathematics, 2005, 65 (5), pp.1547-1575. Thanks to the use of the Cagniard–De Hoop method, we derive an analytic solution in the time domain for the half-space problem associated with the wave equation with Engquist– Majda higher order boundary conditions. This permits us to derive new convergence results when the order of the boundary condition tends to infinity, as well as error estimates. The theory is illustrated by numerical results. (10.1137/S0036139903436145)
  DOI : 10.1137/S0036139903436145
• Another approach to linearized elasticity and a new proof of Korn's inequality
  
  • Ciarlet Patrick
  • Ciarlet Philippe G.
  Mathematical Models and Methods in Applied Sciences, World Scientific Publishing, 2005, 15 (02), pp.259-271. We describe and analyze an approach to the pure traction problem of three-dimensional linearized elasticity, whose novelty consists in considering the linearized strain tensor as the "primary" unknown, instead of the displacement itself as is customary. This approach leads to a well-posed minimization problem, constrained by a weak form of the St Venant compatibility conditions. Interestingly, it also provides a new proof of Korn's inequality. (10.1142/S0218202505000352)
  DOI : 10.1142/S0218202505000352
• Perfectly matched layers for time-harmonic acoustics in the presence of a uniform flow
  
  • Bécache Eliane
  • Bonnet-Ben Dhia Anne-Sophie
  • Legendre Guillaume
  , 2005, pp.35. This paper is devoted to the resolution of the time-harmonic linearized Galbrun's equation, which models, via a mixed Lagrangian-Eulerian representation, the propagation of acoustic and hydrodynamic perturbations in a given flow of a compressible fluid. We consider here the case of a uniform subsonic flow in an infinite, two-dimensional duct. Using a limiting amplitude process, we characterize the outgoing solution radiated by a compactly supported source. Then, we propose a Fredholm formulation with perfectly matched absorbing layers for approximating this outgoing solution. The convergence of the approximated solution to the exact one is proved, and error estimates with respect to the parameters of the absorbing layers are derived. Several significant numerical examples are included.
• Mathematical analysis of the acoustic diffraction by a muffler containing perforated ducts
  
  • Bonnet-Ben Dhia Anne-Sophie
  • Drissi Dora
  • Gmati Nabil
  Mathematical Models and Methods in Applied Sciences, World Scientific Publishing, 2005, 15 (7), pp.1059-1090. We consider the three-dimensional scalar problem of acoustic propagation in a muffler. We develop and analyze a Fredholm-type formulation for a stationary fluid in the timeharmonic setting. We prove a homogenization result for a muffler containing periodically perforated ducts. Essentially, the perforated boundaries become completely transparent when the period of perforations, which is assumed to be of the same order as the size of perforations, tends to zero. We also derive a homogenized impedance condition when the perforated duct is coated by an absorbing material. We present numerical examples in two dimensions, obtained from coupling finite elements in the muffler with modal decompositions in the inlet and outlet ducts, which demonstrate the limiting validity of the theoretical results. © World Scientific Publishing Company. (10.1142/s0218202505000649)
  DOI : 10.1142/s0218202505000649
• Generalized Impedance Impedance Boundary Conditions For Scattering by Strongly Absorbing Obstacles: The Scalar Case
  
  • Haddar Houssem
  • Joly Patrick
  • Nguyen Hoai-Minh
  Mathematical Models and Methods in Applied Sciences, World Scientific Publishing, 2005, 15 (08), pp.1273-1300. (10.1142/S021820250500073X)
  DOI : 10.1142/S021820250500073X
• Singular electromagnetic fields: Inductive approach [Singularités électromagnétiques: Une approche inductive]
  
  • Assous Franck
  • Ciarlet Patrick
  • Garcia Emmanuelle
  Comptes Rendus. Mathématique, Académie des sciences (Paris), 2005, 341 (10), pp.605-610. In a non-convex polyhedral domain, we describe the local trace (i.e. defined on a face) of the normal derivative of an L2 function, with L2 Laplacian. We then provide generalized integration by parts formulae for the Laplace, divergence and curl operators. Finally, these results allow us to split electromagnetic fields into regular and singular parts, which can be characterized. © 2005 Académie des sciences. Published by Elsevier SAS. All rights reserved. (10.1016/j.crma.2005.09.034)
  DOI : 10.1016/j.crma.2005.09.034
• Matching of asymptotic expansions for the wave propagation in media with thin slot
  
  • Tordeux Sébastien
  • Joly Patrick
  , 2005. This talk concerns the modelizing of scattering in the harmonic regime in two dimensional domains with thin slots. We use the technique of matching asymptotic expansions to obtain and justify the asymptotic expansion of the solution to any order with respect to the width of the slot.