Abstract
The aeroacoustical analogy derived by Curle for the prediction of the sound resulting from turbulence/body interaction has been proved quite powerful for low Helmholtz numbers, i.e. when the interaction region is acoustically compact. In such case, incompressible ∞ow modeling is appropriate to obtain the source fleld used as input of the analogy. It was however shown in a previous paper that Curle’s analogy can yield erroneous results for non-compact cases, when an incompressible ∞ow model is adopted. Yet, at low Mach numbers, incompressible ∞ow modeling can be substantially more e‐cient than compressible simulations, due to the stifiness issues faced by the latter. The present work focuses on the derivation of a method combining Curle’s analogy with a Boundary Element Method (BEM), in order to compensate for the weaknesses of the traditional approach at high Helmholtz numbers. The validation of this method is performed by application to a somewhat subtle test case: the leapfrogging of two vortex fllaments in an inflnite two-dimensional duct. This ∞ow model is amenable to a nearly exact derivation by an incompressible vortex model. Moreover, the acoustic fleld can also be obtained very accurately using the tailored Green’s function based on the duct modes, providing a reference solution to validate our numerical approach. A number of implementation issues have been investigated such as the in∞uence of acoustic boundary conditions and the scaling needed to compare two-dimensional and three-dimensional acoustic simulations. The sound fleld predicted using the Curle/BEM approach shows an excellent agreement with the reference solution based on the tailored Green’s function, thereby validating the general principle of our method and its numerical implementation.
Published Version
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