Localisation of a stationary time-harmonic dipole sound source in flows using time-reversal simulation
Date
2013
Authors
Mimani, A.
Doolan, C.
Medwell, P.
Editors
Terrance McMinn,
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Conference paper
Citation
Proceedings of Acoustics 2013 Victor Harbor: Science Technology and Amenity, Annual Conference of the Australian Acoustical Society, 17-20 November, 2013/ Terrance McMinn (ed.): 8p.
Statement of Responsibility
Akhilesh Mimani, Con Doolan, Paul Medwell
Conference Name
Acoustics 2013 : Science, Technology and Amenity (2013 : Victor Harbor, South Australia)
Abstract
This work analyses the accuracy of numerical Time-Reversal (TR) simulations implemented using two different Time-Reversal Mirror (TRM) configurations for localising and characterising a stationary acoustic dipole source in a mean flow. The forward time evolution of the acoustic fields is simulated by means of the numerical solution of the inhomogeneous 2-D Linearised Euler Equations (LEE) with uniform subsonic mean flow. Only the acoustic pressure is recorded with two line arrays (LAs) of boundary nodes in a TRM corresponding to the top and bottom boundaries. The time-reversed acoustic pressure history is used as input data for simulating two numerical TR experiments; (a) one line array (LA) in a TRM corresponding to the top boundary and (b) two LAs in a TRM corresponding to the top and bottom boundaries. The Root-Mean-Square (RMS) of the time-reversed acoustic pressure field obtained by the first experiment indicates only one spatial maxima region (focal spot), therefore incorrectly suggests that the source is a monopole, whereas the second experiment correctly reveals the source to be a dipole. The local acoustic pressure history at two source locations is shown to be coherent with relative phase exactly equal to radian, thereby confirming the dipole source nature. This demonstrates that two LAs in a TRM located on either sides of the mean flow are required to take into consideration, the complete phase information and thereby accurately characterise a dipole.
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Copyright © 2013, The Australian Acoustical Society