Search for dissertations about: "Acoustic wave propagation"

Showing result 1 - 5 of 63 swedish dissertations containing the words Acoustic wave propagation.

  2. 1. Shape Optimization for Acoustic Wave Propagation Problems

    Author : Rajitha Udawalpola; Martin Berggren; Pekka Neittaanmäki; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; shape optimization; design optimization; acoustic wave propagation; Helmholtz equation; Boundary Element Method; Finite Element Method; inverse problems; adjoint method; gradient-based optimization; Scientific Computing; Beräkningsvetenskap;

    Abstract : 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. READ MORE

  4. 2. A Wave Expansion Method for Aeroacoustic Propagation

    Author : Johan Hammar; Gunilla Efraimsson; Ciarán J. O'Reilly; Wim De Roeck; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Sound propagation; Sound generation; Aeroacoustics; Aerodynamics; Computational fluid dynamics; Computational aeroacoustics; Numerical methods; Lighthill; Curle; Ffowcs Williams and Hawkings; Frequency-domain propagation; Wave expansion method.; Vehicle and Maritime Engineering; Farkostteknik;

    Abstract : Although it is possible to directly solve an entire flow-acoustics problem in one computation, this approach remains prohibitively large in terms of the computational resource required for most practical applications. Aeroacoustic problems are therefore usually split into two parts; one consisting of the source computation and one of the source propagation. READ MORE

  5. 3. Numerics of Elastic and Acoustic Wave Motion

    Author : Kristoffer Virta; Gunilla Kreiss; Anders Petersson; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; finite differences; stability; high order accuracy; elastic wave equation; acoustic wave equation; Beräkningsvetenskap med inriktning mot numerisk analys; Scientific Computing with specialization in Numerical Analysis;

    Abstract : The elastic wave equation describes the propagation of elastic disturbances produced by seismic events in the Earth or vibrations in plates and beams. The acoustic wave equation governs the propagation of sound. READ MORE

  6. 4. Topology optimization for acoustic wave propagation problems

    Author : Eddie Wadbro; Martin Berggren; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Scientific Computing; Beräkningsvetenskap;

    Abstract : The aim of this study is to develop numerical techniques for the analysis and optimization of acoustic horns for time harmonic wave propagation. An acoustic horn may be viewed as an impedance transformer, designed to give an impedance matching between the feeding waveguide and the surrounding air. READ MORE

  7. 5. Theoretical and numerical studies of sound propagation in low-Mach-number duct flows

    Author : Chenyang Weng; Mats Åbom; Susann Boij; Ardeshir Hanifi; Anurag Agarwal; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Aeroacoustics; Acoustic wave absorption; Acoustic wave propagation; Boundary layer turbulence; DNS; Engineering Mechanics; Teknisk mekanik;

    Abstract : When sound waves propagate in a duct in the presence of turbulent flow, turbulent mixing can cause attenuation of the sound waves extra to that caused by the viscothermal effects. Experiments show that compared to the viscothermal effects, this turbulent absorption becomes the dominant contribution to the sound attenuation at sufficiently low frequencies. READ MORE