Modélisation par une approche temporelle de la propagation acoustique en milieu extérieur : traitement de frontières complexes et validation sur site ferroviaire
type: Dataset
contact point: Organization
  fn: CCSD
keyword: spiotherengineering-sciences-physicsother
keyword: infoeu-reposemanticsdoctoralthesis
keyword: equations-deuler
keyword: methode-split-step-pade
keyword: site-ferroviaire
keyword: champ-lointain
keyword: sols-impedants
keyword: propagation-acoustique
keyword: aeroacoustique-numerique
keyword: milieu-exterieur
keyword: couplage-champ-proche
keyword: theses
landing page: https://theses.hal.science/tel-00687519
description: In this work, a numerical model to treat outdoor sound propagation in the time domain is proposed. In the context of railway noise, extended acoustic sources in motion have to be considered. The typical frequency band of interest goes up to 8000 Hz. Finite-Difference Time-Domain(FDTD) methods which are used to solve the linearized Euler equations are then well-adapted tothe problem. To do so, finite-difference techniques developed in the computational aeroacoustics community are employed. Meteorological effects (mean wind and temperature profiles) as well as ground effects (impedance and topography) are taken into account. In the first chapter, finite-difference techniques and the time-domain impedance boundary condition, based on a recursive convolution, are presented in the general case of the tridimensional problem. Propagation of acoustic waves in a stratified atmosphere over an impedance ground is then considered. In homogeneous conditions, waveforms are compared to those obtained with an analytical solution. In downward-refracting conditions, arrival times of the different contributions are analysed using a geometrical acoustic approach. In both cases, presence of surface waves is highlighted. At last, in a first analysis, effects of a non-compact source in rectilinear motion on the acoustic pressure field are studied. In the second chapter, the coupling between near-field calculations and far-field calculations is considered. Indeed, the FDTD model currently needs large computational time and memory to handle large propagation distances. A coupling strategy using parabolic equation methods can then be employed. A split-step Padé method is used in order to choose the angular validity of the parabolic approximation. A study on the starting field adapted to the order of the Padé approximant is proposed. The third chapter deals with the modeling of the topography in the FDTD solver. Curvilinear coordinates are introduced, and numerical resolution is similar to th…
identifier: NNT: 2011ECDL0035
issued: 2026-05-22T00:37:10.980725
language: fr
modified: 2026-05-22T00:37:10.980732

test_moissonnage_selune
type: Agent

Modélisation par une approche temporelle de la propagation acoustique en milieu extérieur : traitement de frontières complexes et validation sur site ferroviaire
type: Distribution
access URL: https://theses.hal.science/tel-00687519
format: HTML
issued: 2026-05-22T00:37:11.081960
modified: 2026-05-22T00:37:10.927960