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Published August 27, 2017 | Version v1
Conference paper Open

Analogue transformation acoustics in aeronautics

  • 1. University of Roma Tre

Description

The objective of the paper is a critical review within the context of aeronautical applications of the Analogue
Transformation Acoustics (ATA) approach for the modelling of acoustic metamaterials. The ATA
approach has been introduced to overcome the limitation of the metamaterials design methods based on
the Standard Transformation Acoustics (STA) imposed by the requirement of a strict formal invariance
of the governing equations. Indeed, in case of acoustic perturbations propagating within moving media,
the convective terms are responsible of the failure of formal invariance under the action of conformal
mappings as a consequence of the combination of space and time derivatives. The ATA is based on the
concept of analogue spacetimes and fully relies on the analytical tools of Lorentzian differential geometry.
The great advantages of the method is the possibility to handle a background flow, conversely to the
STA which fails in presence of convection. Despite the undoubted appeal of this feature in the eyes of
an aeroacoustician, its potential has not been completely disclosed yet. The class of transformations that
yield a physically meaningful aerodynamics in the virtual analogue spacetime has not been explored in
details, preventing the application of the method in aeronautics. The present paper analyses the relationship
between the the analogue velocity field with a realistic potential flow. The analytical comparison is
validated through numerical simulations of two classic benchmarks: the irrotational flow of an inviscid,
incompressible fluid around a circular cylinder and the flow through a bumped wall. The target acoustic
behaviour is the cancellation of the scattering (cloaking) induced by the cylinder and the bump.

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Analogue Transformation Acoustics in Aeronautics.pdf

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Additional details

Funding

AERIALIST – AdvancEd aicRaft-noIse-AlLeviation devIceS using meTamaterials 723367
European Commission