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Shape Optimization for Acoustic Wave Propagation Problems
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Boundary shape optimization is a technique to search for an optimal shape by modifying the boundary of a device with a pre-specified topology. We consider boundary shape optimization of acoustic horns in loudspeakers and brass wind instruments. A horn is an interfacial device, situated between a source, such as a waveguide or a transducer, and surrounding space. Horns are used to control both the transmission properties from the source and the spatial power distribution in the far-field (directivity patterns).

Transmission and directivity properties of a horn are sensitive to the shape of the horn flare. By changing the horn flare we design transmission efficient horns. However, it is difficult to achieve both controllability of directivity patterns and high transmission efficiency by using only changes in the horn flare. Therefore we use simultaneous shape and so-called topology optimization to design a horn/acoustic-lens combination to achieve high transmission efficiency and even directivity. We also design transmission efficient interfacial devices without imposing an upper constraint on the mouth diameter. The results demonstrate that there appears to be a natural limit on the optimal mouth diameter.

We optimize brasswind instruments with respect to its intonation properties. The instrument is modeled using a hybrid method between a one-dimensional transmission line analogy for the slowly flaring part of the instrument, and a finite element model for the rapidly flaring part.

An experimental study is carried out to verify the transmission properties of optimized horn. We produce a prototype of an optimized horn and then measure the input impedance of the horn. The measured values agree reasonably well with the predicted optimal values.

The finite element method and the boundary element method are used as discretization methods in the thesis. Gradient-based optimization methods are used for optimization, in which the gradients are supplied by the adjoint methods.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2010. , p. 42
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 709
Keywords [en]
shape optimization, design optimization, acoustic wave propagation, Helmholtz equation, Boundary Element Method, Finite Element Method, inverse problems, adjoint method, gradient-based optimization
National Category
Computational Mathematics
Research subject
Scientific Computing
Identifiers
URN: urn:nbn:se:uu:diva-112549ISBN: 978-91-554-7707-3 (print)OAI: oai:DiVA.org:uu-112549DiVA, id: diva2:286603
Public defence
2010-02-26, Room 2446, Polacksbacken, Lägerhyddsvägen 2D, Uppala, 10:15 (English)
Opponent
Supervisors
Available from: 2010-02-03 Created: 2010-01-14 Last updated: 2011-10-26Bibliographically approved
List of papers
1. Optimization of an acoustic horn with respect to efficiency and directivity
Open this publication in new window or tab >>Optimization of an acoustic horn with respect to efficiency and directivity
2008 (English)In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 73, p. 1571-1606Article in journal (Refereed) Published
National Category
Computational Mathematics Computer Sciences
Identifiers
urn:nbn:se:uu:diva-56368 (URN)10.1002/nme.2132 (DOI)000254457600004 ()
Projects
Design Optimization
Available from: 2008-08-29 Created: 2008-08-29 Last updated: 2018-01-11Bibliographically approved
2. Shape and topology optimization of an acoustic horn-lens combination
Open this publication in new window or tab >>Shape and topology optimization of an acoustic horn-lens combination
2010 (English)In: Journal of Computational and Applied Mathematics, ISSN 0377-0427, E-ISSN 1879-1778, Vol. 234, p. 1781-1787Article in journal (Refereed) Published
National Category
Computational Mathematics Computer Sciences
Identifiers
urn:nbn:se:uu:diva-98374 (URN)10.1016/j.cam.2009.08.028 (DOI)000278570900022 ()
Projects
Design Optimization
Available from: 2009-02-20 Created: 2009-02-20 Last updated: 2018-01-13Bibliographically approved
3. Optimization of a variable mouth acoustic horn
Open this publication in new window or tab >>Optimization of a variable mouth acoustic horn
2011 (English)In: International Journal for Numerical Methods in Engineering, ISSN 0029-5981, E-ISSN 1097-0207, Vol. 85, p. 591-606Article in journal (Refereed) Published
National Category
Computational Mathematics Computer Sciences
Identifiers
urn:nbn:se:uu:diva-112191 (URN)10.1002/nme.2982 (DOI)000286775000004 ()
Projects
Design Optimization
Available from: 2010-01-13 Created: 2010-01-11 Last updated: 2018-01-12Bibliographically approved
4. A hybrid scheme for bore design optimization of a brass instrument
Open this publication in new window or tab >>A hybrid scheme for bore design optimization of a brass instrument
2010 (English)In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 128, p. 1391-1400Article in journal (Refereed) Published
National Category
Computational Mathematics
Identifiers
urn:nbn:se:uu:diva-112193 (URN)10.1121/1.3466871 (DOI)000281799800049 ()
Projects
Design Optimization
Available from: 2010-01-13 Created: 2010-01-11 Last updated: 2017-12-12Bibliographically approved
5. An efficient loudspeaker horn designed by numerical optimization: An experimental study
Open this publication in new window or tab >>An efficient loudspeaker horn designed by numerical optimization: An experimental study
Show others...
2010 (English)Report (Other academic)
Place, publisher, year, edition, pages
Department of Computing Science, Umeå University, 2010
Series
Report / UMINF, ISSN 0348-0542 ; 10.01
National Category
Computational Mathematics
Identifiers
urn:nbn:se:uu:diva-112514 (URN)
Projects
Design Optimization
Available from: 2010-01-14 Created: 2010-01-14 Last updated: 2011-11-17Bibliographically approved

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Udawalpola, Rajitha

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