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    Item type:Publication, Access status: without files ,
    Fast algorithms applied to the acoustical energy boundary element method
    (2019-09)
    Ram, Matthias Wolf Christian
    ;
    Estorff, Otto von
    The Energy Boundary Element Method (EBEM) aims at the solution of acoustic high frequency problems, where the classic BEM becomes inefficient due to the large number of degrees of freedom (DOF) required. A transition to non-phased energetic state variables removes the correlation between the investigated frequency range and the element size. In the EBEM the number of DOF is thus determined primarily by the complexity of the geometry. In order to speed up the computation and to handle structures of very high geometric complexity, a fast multipole algorithm for the EBEM is investigated. It has a great potential to reduce the numerical effort in the Boundary Element Method (BEM). Helmholtz and Laplace problems have been solved very efficiently applying this algorithm. However, the kernels used in the EBEM require an adaptation of the algorithm. In this paper the development of a fast multipole formulation of the EBEM is presented.
    Publicationtype: Conference Paper
      44
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    Analysis Methods and Design Measures for the Reduction of Noise and Vibration Induced by Marine Propellers
    (Deutsche Gesellschaft für Akustik, 2019-09)
    Kimmerl, Julian
    ;
    Mertes, Paul
    ;
    Krasilnikov, Vladimir
    ;
    Koushan, Kourosh
    ;
    Savio, Luca
    The paper presents the ongoing work in the research project ProNoVi. The objective of the project is to improve the numerical and experimental methods for the prediction of noise and vibrations induced by a propeller operating behind ship hull in full-scale conditions. Based on the improved methods practical recommendations for the reduction of noise and vibration levels for diơerent classes of vessels are a further objective. The propeller cavitation noise is identified as the dominating noise source, which coincides with important frequencies of perception of marine fauna and thus may have negative impact on marine life. As a side eơect, reducing the noise under water will increase comfort and thus safety for crew and passengers on board. The project aims at delivering a better understanding of fundamental physical mechanisms related to turbulence, induced vorticity and cavitation dynamics, which play a decisive role in generation of tonal and broadband propeller noise. The project partners will give a joint presentation, focusing on state-of-the-art in the field, today’s challenges in both the experimental and numerical approaches, and how the ProNoVi project is addressing those. ProNoVi is funded by the European Union. Further information is available at www.martera.eu/projects/pronovi.
    Publicationtype: Conference Paper
      93