Acoustic Resonance Scattering by Submerged Elastic Shells

Gaunaurd, G. C.; Werby, M. F.

doi:10.1115/1.3119168

Cited by 64 publications

(16 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The interaction between acoustical and structural waves covers a very broad range of topics, with an equally broad range of techniques; from formal mathematical analyses (see, for example, [5]) to more applied research concerned with submarine acoustics [6]. In terms of physical problems, there are obvious applications, such as the generation of noise by flows past elastic structures (see, for example, [7]), flow in pipes [8], scattering of water waves by flexible ice sheets [9,10], and the insonification of underwater elastic shells [11] amongst many others. The field itself has an illustrious history: the overview of the influence of fluid-loading on vibrating structures provided by Crighton's 1998 Rayleigh Medal lecture [12] notes that it is almost impossible to find an area of research in wave motion where Lord Rayleigh has not worked and that fluid-loaded structures are no exception.…”

Section: Introductionmentioning

confidence: 99%

The multi-physics metawedge: graded arrays on fluid-loaded elastic plates and the mechanical analogues of rainbow trapping and mode conversion

et al. 2018

View full text Add to dashboard Cite

We consider the propagation and mode conversion of flexural-acoustic waves along a fluid-loaded graded array of elastic resonators, forming a metasurface. The multi-physics nature of the problem, coupling two disparate physical systems, brings both challenges and novel features not previously seen in so-called bifunctional metamaterials. In particular, by using an appropriately designed graded array of resonators, we show that it is possible to employ our metasurface to mode-convert sub-sonic surface flexural waves into bulk acoustic waves and vice-versa; transferring energy between two very different physical systems. Whilst the sub-sonic mechanical surface wave is dispersive, the bulk acoustic wave is dispersionless and radiates energy at infinity. We also show that this bifunctional metasurface is capable of exhibiting the classical effect of rainbow trapping for sub-sonic surface waves.An active area of research in metasurfaces [25] focuses upon graded resonator metasurfaces, where the general concept is that for a graded surface, or waveguide, different wavelengths are trapped at different spatial positions. Sub-wavelength microstructures are commonly employed in two ways: the first approach is to create effective macroscopic wavespeeds that vary spatially, thus achieving the required control of wave propagation. The second approach involves using deep sub-wavelength resonances to obtain the desired effects. Whilst the latter approach is significantly more difficult to create, it is far more powerful; hence our aim in the present paper is to extend this latter concept to fluid-loaded compliant structures. These ideas are being widely adopted in photonics and phononics due to their excellent abilities to control, manipulate and filter waves in compact devices. Graded and chirped designs include: trapping in rainbow devices [26][27][28][29], flat focussing mirrors and lenses in optics, plasmonics and acoustics [30][31][32][33][34][35], gradient index lens for acoustic and flexural waves focussing [36,37], acoustic absorbers [38][39][40] and sound enhancement [41,42].In the absence of the fluid-loading, it is only very recently that graded sub-wavelength structures for thin elastic plates has been considered as a chirped graded array [43], thin beams [44] or in the context of gradient index (GRIN) lenses created by graded structuration to control elastic symmetric (S 0 ) and antisymmetric (A 0 ) waves [45] and to obtain deeply sub-wavelength focussing [46], cloaking [47] and GRIN lenses (e.g. Luneburg, Maxwell-fisheye and Eaton lenses [44, 48]) using resonator arrays [37]. There is also an active community in so-called platonics [49] studying the generalisations of phononic crystals to elastic plates in-vacuo with considerable progress in pulling out features associated with Dirac cones [50], dynamic anisotropy and lensing /shielding effects [51]. Much of this is concerned with mass-loaded or constrained plates, but recent work on resonator arrays on plates [52] has moved this into contemporary areas of physics...

show abstract

Section: Introductionmentioning

confidence: 99%

The multi-physics metawedge: graded arrays on fluid-loaded elastic plates and the mechanical analogues of rainbow trapping and mode conversion

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Despite the extensive analyses related to plane wave scattering by an infinitely-long cylinder, 2,[6][7][8][9] earlier works considered the case of beams, based on the angular spectrum decomposition of plane waves, requiring the numerical evaluation of indefinite integrals. 10,11 On the other hand, the present analysis is based on the partial-wave series expansion (PWSE) method (known also as normal-mode decomposition in Fourier series) in cylindrical coordinates, and the evaluation of the beam-shape coefficients (BSCs) stemming from Graf's additional theorem for the cylindrical wave functions, without the need of numerical integration procedures, used previously in the method of the angular spectrum decomposition into plane waves, or in the computation of the acoustic radiation force on a rigid (sound impenetrable) cylinder.…”

Section: Introductionmentioning

confidence: 99%

Resonance scattering and radiation force calculations for an elastic cylinder using the translational addition theorem for cylindrical wave functions

Mitri

2015

AIP Advances

View full text Add to dashboard Cite

The standard Resonance Scattering Theory (RST) of plane waves is extended for the case of any two-dimensional (2D) arbitrarily-shaped monochromatic beam incident upon an elastic cylinder with arbitrary location using an exact methodology based on Graf's translational addition theorem for the cylindrical wave functions. The analysis is exact as it does not require numerical integration procedures. The formulation is valid for any cylinder of finite size and material that is immersed in a nonviscous fluid. Partial-wave series expansions (PWSEs) for the incident, internal and scattered linear pressure fields are derived, and the analysis is further extended to obtain generalized expressions for the on-axis and off-axis acoustic radiation force components. The wave-fields are expressed using generalized PWSEs involving the beam-shape coefficients (BSCs) and the scattering coefficients of the cylinder. The off-axial BSCs are expressed analytically in terms of an infinite PWSE with emphasis on the translational offset distance d. Numerical computations are considered for a zeroth-order quasi-Gaussian beam chosen as an example to illustrate the analysis. Acoustic resonance scattering directivity diagrams are calculated by subtracting an appropriate background from the expression of the scattered pressure field. In addition, computations for the radiation force exerted on an elastic cylinder centered on the axis of wave propagation of the beam, and shifted off-axially are analyzed and discussed. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

show abstract

“…As an example in the field of acoustics, this topic is investigated extensively in underwater applications [2][3][4][5] with the aim of indentifying targets from their sonar echoes. In most of these important investigations, scattering from plane (axisymmetric) waves is only considered [6].…”

Section: Introductionmentioning

confidence: 99%

Off-axial acoustic scattering of a high-order Bessel vortex beam by a rigid sphere

Mitri

Silva

2011

Wave Motion

View full text Add to dashboard Cite

In this paper, the off-axial acoustic scattering of a high-order Bessel vortex beam by a rigid immovable (fixed) sphere is investigated. It is shown here that shifting the sphere off the axis of wave propagation induces a dependence of the scattering on the azimuthal angle. Theoretical expressions for the incident and scattered field from a rigid immovable sphere are derived. The near-and far-field acoustic scattering fields are expressed using partial wave series involving the spherical harmonics, the scattering coefficients of the sphere, the half-conical angle of the wave number components of the beam, its order and the beam-shape coefficients. The scattering coefficients of the sphere and the 3D scattering directivity plots in the near-and farfield regions are evaluated using a numerical integration procedure. The calculations indicate that the scattering directivity patterns near the sphere and in the far-field are strongly dependent upon the position of the sphere facing the incident high-order Bessel vortex beam.

show abstract

Acoustic Resonance Scattering by Submerged Elastic Shells

Cited by 64 publications

References 84 publications

The multi-physics metawedge: graded arrays on fluid-loaded elastic plates and the mechanical analogues of rainbow trapping and mode conversion

The multi-physics metawedge: graded arrays on fluid-loaded elastic plates and the mechanical analogues of rainbow trapping and mode conversion

Resonance scattering and radiation force calculations for an elastic cylinder using the translational addition theorem for cylindrical wave functions

Off-axial acoustic scattering of a high-order Bessel vortex beam by a rigid sphere

Contact Info

Product

Resources

About