Multiple-scale modelling of acoustic sources in low Mach-number flow |
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Authors: | Claus-Dieter Munz Roland Fortenbach Michael Dumbser |
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Institution: | Institut für Aerodynamik und Gasdynamik, Universität Stuttgart, Pfaffenwaldring 21, 70550 Stuttgart, Germany |
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Abstract: | The main difficulty in the calculation of sound generated by fluid flow at low Mach numbers is the occurrence of different scales. The fluid flow is characterized by small spatial structures containing a large amount of energy that may propagate with a small convective velocity, such as small vortices in a turbulent flow. The radiated acoustic waves have small amplitudes and carry a small amount of energy, but have a long wavelength due to their fast propagation velocity. In this paper a perturbation method is used to calculate noise generation and propagation in combination with fluid flow based on the incompressible equations. The idea for the numerical modelling is to introduce a fine grid for the resolution of the fluid flow that is embedded into a larger acoustical domain with a coarse grid adapted to the long wavelength acoustics. To get an appropriate restriction of the acoustic source terms from the fine CFD-grid to the coarse CAA-grid, a multi-scale expansion with one time and two space scales is introduced. To cite this article: C.-D. Munz et al., C. R. Mecanique 333 (2005). |
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Keywords: | Acoustics Acoustic source modelling Low Mach number flows Multi-scale asymptotic analysis Acoustique Modélisation des sources acoustiques Écoulements à faible nombre de Mach Analyse asymptotique multi-échelles |
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