An m -multipole particle-condensation method is proposed to spatially condense the volumetric quadrupole sources based on Lighthill’s acoustic analogy that are extracted from computational-fluid-dynamics data. The purpose of the method is to reduce both the amount of data that must be stored during the computational-fluid-dynamics analysis and the number of acoustic sources driving the subsequent acoustic-propagation analysis, while preserving the accuracy of the predicted sound pressure field. The method uses a particle approximation of the quadrupole source distribution and employs a Taylor series expansion of the harmonic Green’s function to spatially condense the underlying acoustic sources and preserve their multipole moments. Low-Mach-number flow around rigid-walled stationary bodies in a medium at rest at infinity is used to demonstrate the m -multipole particle-condensation method. The directivity of the sound pressure field due to the quadrupole sources is presented for the first four harmonics of the vortex-shedding frequency for flow past a circular cylinder with Reynolds number R e D = 100 and Mach number M = 0.02 . Using the m -multipole particle-condensation method, the number of acoustic sources is reduced by a factor of 120 with the associated far-field sound pressure levels within 0.5 dB of the noncondensed results for all four harmonics.


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    Title :

    Fast Low-Storage Method for Evaluating Lighthill’s Volume Quadrupoles


    Contributors:
    Croaker, P. (author) / Kessissoglou, N. (author) / Kinns, R. (author) / Marburg, S. (author)

    Published in:

    AIAA Journal ; 51 , 4 ; 867-884


    Publication date :

    2013-04-01




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English