Simplified model of a harmonic point source moving above an impedance ground

Francis Golay (1) , Guillaume Dutilleux (1) , Laurent Simon (2) , Christophe Ayrault (2) , Franck Poisson (3)

1 CETE Est - Centre d'études techniques de l'équipement Est
2 LAUM - Laboratoire d'Acoustique de l'Université du Mans
3 SNCF - DIR

Transportation noise is an important source in terms of annoyance in urban and suburban area. Modelling sound propagation from these moving sources needs an efficient prediction tool. The classical theory due to Morse and Ingard is limited to free space. A reference model has been proposed for modelling the pressure field generated by a harmonic point source moving above a flat impedance ground which takes into account the spherical wave reflection coefficient. The complexity of the reference model has resulted in a heuristic model intuitively derived from a model for a motionless harmonic sound source, by including Doppler corrections. However the predictions of this heuristic model are significantly different from those of the reference model. In this paper, we propose a simplification of the reference model, by approximating the variables by constants or by linear expressions on small time intervals. Compared with the reference model, this simplified model is faster. In addition, it makes the physical link between the reference and the heuristic models. Numerical simulations confirm the accuracy of the simplified model.

Mots clés: moving source; simplified model

Domaines: Acoustique [physics.class-ph]

Francis Golay, Guillaume Dutilleux, Laurent Simon, Christophe Ayrault, Franck Poisson. Simplified model of a harmonic point source moving above an impedance ground. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810554⟩