2019_programme: INFLUENCE OF FLUID-STRCTURE COUPLING ON TARGET ECHO STRENGTH SIMULATION



  • Session: 21. Target Echo Strength-Measurements and Modelling
    Organiser(s): Williams Duncan, Nunn David, Nijhof Marten
  • Lecture: INFLUENCE OF FLUID-STRCTURE COUPLING ON TARGET ECHO STRENGTH SIMULATION
    Paper ID: 996
    Author(s): Schaefer Ingo, Ehrlich Jan, Burgschweiger Ralf, Ochmann Martin
    Presenter: Ehrlich Jan
    Presentation type: oral
    Abstract: A combined Boundary Element – Finite Element method for the calculation of the Target Echo Strength (TES) of an underwater object is presented. For the calculation of TES in the high frequency range it is not necessary to consider fluid-structure-coupling. In this case it is possible to use a raytracing based algorithm together with a Kirchhoff scattering approximation. Better results can be obtained by using a method like the BEM, that is able to include the influence of the mass of object as a thin shell. But for the low frequency region the elastic response of the object has to be considered as well. This demands the application of a full fluid-structure interaction, which can be done with a BEM-FEM coupling. Three different formulations for this coupling will be explained and compared. Results of calculations for a test object consisting of a water-filled steel cylinder with one semi-spherical end cap with the different coupling algorithms will be presented. The coupled approach makes it possible to detect TES highlights at several frequencies that are caused by eigenmodes. It will be shown that only some eigenmodes are able to radiate. The presented BEM-FEM approach is able to calculate the TES of models consisting of more than a million elements.
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  • Corresponding author: Mr Ehrlich Jan
    Affiliation: Bundeswehr WTD 71
    Country: Germany
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