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dc.contributor.authorZagadou, Francken_US
dc.date.accessioned2021-03-26T17:50:16Z
dc.date.available2021-03-26T17:50:16Z
dc.date.issued2002
dc.identifier.urihttps://hdl.handle.net/2144/42324
dc.description.abstractThe sound generated by high speed trains can be exacerbated by the presence of trackside structures. Tunnels are the principal structures that have a strong influence on the noise produced by trains. A train entering a tunnel causes air to flow in and out of the tunnel portal, forming a monopole source of low frequency sound ["infrasound"] whose wavelength is large compared to the tunnel diameter. For the compact case, when the tunnel diameter is small, incompressible flow theory can be used to compute the Green's function that determines the monopole sound. However, when the infrasound is "shielded" from the far field by a large "flange" at the tunnel portal, the problem of calculating the sound produced in the far field is more complex. In this case, the monopole contribution can be calculated in a first approximation in terms of a modified Compact Green's function, whose properties are determined by the value at the center of a. disk (modelling the flange) of a diffracted potential produced by a thin circular disk. In this thesis this potential is calculated numerically. The scattering of sound by a thin circular disk is investigated using the Finite Difference Method applied to the three dimensional Helmholtz equation subject to appropriate boundary conditions on the disk. The solution is also used to examine the unsteady force acting on the disk.en_US
dc.language.isoen_US
dc.publisherBoston Universityen_US
dc.rightsThis work is being made available in OpenBU by permission of its author, and is available for research purposes only. All rights are reserved to the author.en_US
dc.subjectFinite Difference methoden_US
dc.subjectHelmholtz equationen_US
dc.subjectAerospace and mechanical engineeringen_US
dc.titleNumerical analysis of acoustic scattering by a thin circular disk, with application to train-tunnel interaction noiseen_US
dc.typeThesis/Dissertationen_US
etd.degree.nameMaster of Scienceen_US
etd.degree.levelmastersen_US
etd.degree.disciplineAerospace and Mechanical Engineeringen_US
etd.degree.grantorCollege of Engineeringen_US


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