The paper presents the implementation of a procedure for aero-acoustics, using the Acoustic Analogy first presented by Lighthill, which has been implemented in numerical processes using computational fluid dynamics and boundary element acoustic modelling. The process extracts the acoustic source terms from numerical solutions of the unsteady fluid dynamics. From these data, it generates sets of sources for an acoustic radiation model. The sources can be quadrupoles (within the field, for example in turbulent wakes); dipoles (on surfaces, where the flow causes fluctuating pressure); monopoles (where there is mass-flow fluctuation across a boundary of the region considered). A special fan noise source is also implemented, for rotating dipoles (where there is fluctuating pressure on surfaces which rotate about an axis). Using standard CFD codes and the acoustic-modelling program SYSNOISE, the sources are generated in an automated way from the CFD results. The paper presents the methodology and its means of use, with practical aspects such as: what type of CFD methods may be needed, CFD mesh refinement versus acoustic meshes, determining the significant source regions, data transfer methods, data storage and computer resource requirements, pre- and post-processing. The paper is illustrated with some examples and verifications.
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