Scattering of a plane acoustic wave by a spherical elastic shell near a free surface

Huang, H.; Gaunaurd, G. C.

doi:10.1016/s0020-7683(96)00033-9

Cited by 31 publications

(16 citation statements)

References 5 publications

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“…Realizing the crowd of parameters and the relatively large sized matrices involved here, while keeping in view our computing hardware limitations, we have to confine our attention to a particular model in a specific frequency range. The surrounding ambient fluid is assumed to be water at atmospheric pressure and 300 kelvin (¯ =0.997 g/cm 3 , c =149 700 cm/s). Accurate computation of the Bessel functions is achieved by employing the MATLAB specialized math functions "besselh" and "besselj."…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…Gaunaurd and Huang (2) employed the translational addition theorems for the spherical wave functions to study acoustic scattering by a hard spherical body near a hard flat boundary. They also considered acoustic scattering by a thin spherical elastic shell near a free surface (3) , and by an ideal air-bubble near the sea surface (4) . More recently, Hasheminejad (5) examined acoustic radiation from a spherical surface undergoing harmonic modal vibrations near a locally reacting (finite impedance) planar boundary.…”

Section: Introductionmentioning

confidence: 99%

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Scattering of Plane Waves by a Rigid Sphere in an Acoustic Quarterspace

Hasheminejad

Badsar

2005

JSME international journal. Ser. B, Fluids and thermal engineer

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The acoustic scattering by a submerged spherical rigid obstacle near an acoustically hard concave corner, which is insonified by plane waves at arbitrary angles of incidence, is studied. The formulation utilizes the appropriate wave-harmonic field expansions and the classical method of images in combination with the translational addition theorems for spherical wave functions to develop a closed-form solution in form of infinite series. The analytical results are illustrated by numerical examples where the spherical object is located near the rigid boundary of a fluid-filled quarterspace and is insonified by plane waves at oblique angles of incidence. Subsequently, the basic acoustic field quantities such as the form function amplitude, the scattered far-field pressure, and the scattered acoustic intensity are evaluated for representative values of the parameters characterizing the system. The limiting case involving a spherical object submerged in an acoustic halfspace is considered and good agreement with a well-known solution is established.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Scattering of Plane Waves by a Rigid Sphere in an Acoustic Quarterspace

Hasheminejad

Badsar

2005

JSME international journal. Ser. B, Fluids and thermal engineer

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“…The velocity of each piston can be expressed as a linear combination of spherical modes in the form of infinite series (3) where and are the modal coefficients of surface velocity distributions. These coefficients can readily be determined after multiplying both sides of (3) by , , integrating over , and subsequently applying the orthogonality property of the Legendre functions: (4) where the integrations are performed by using the following well-known relation [14] (5) Many radiation and scattering problems involve waves of one characteristic shape (coordinate system) that are incident upon a boundary of some other shape (coordinate system). So it is difficult to satisfy the boundary conditions on that surface.…”

Section: Mathematical Formulationmentioning

confidence: 99%

“…References [1] and [2] have each employed distinct analytical methods to examine acoustic scattering of plane compressional waves by two identical rigid and elastic spheres, respectively. The method of images in combination with the translational addition theorems for the spherical wave functions are extensively employed to study acoustic scattering by a hard spherical body near a hard flat boundary [3], by a thin spherical shell near a free (pressure release) surface [4], and by an ideal air-bubble near the sea surface [5]. Axisymmetric acoustic radiation from a spherical source vibrating with an arbitrary, time-harmonic velocity distribution while positioned wholly outside a fluid sphere is examined in [6].…”

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confidence: 99%

Acoustic Radiation From a Pulsating Spherical Cap Set on a Spherical Baffle Near a Hard/Soft Flat Surface

Hasheminejad

Azarpeyvand

2004

IEEE J. Oceanic Eng.

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Abstract-Radiation of sound from a spherical piston, set in the side of a rigid sphere, undergoing harmonic radial surface vibrations in an acoustic halfspace is analyzed in an exact fashion using the classical method of separation of variables. The method of images in combination with the translational addition theorems for spherical wave functions is employed to take the presence of the flat boundary into account. The analytical results are illustrated with numerical examples in which the piston is pulsating near the rigid/compliant boundary of a water-filled halfspace. Subsequently, the basic acoustic field quantities such as the acoustic radiation impedance load and the radiation intensity distribution are evaluated for representative values of the parameters characterizing the system. Numerical results reveal the important effects of excitation frequency, source position, and cap angle on the acoustic radiation impedance load and the radiation intensity distribution. The presented work can lead to a better understanding of dynamic response of near-surface underwater transducers.

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“…Sound scattering by an elastic spherical shell subject to an incoming planar wave was extended to the case of a shell located near a free-surface or a hard ground (Huang, Gaunaurd, 1997). The image method and the collocation approach were pursued by building elements on the shell's surface.…”

Section: Introductionmentioning

confidence: 99%

Sound Scattering by an Elastic Spherical Shell and its Cancellation using a Multi-pole Approach

Avital

Bholah

Giovanelli

et al. 2017

Archives of Acoustics

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The scattering and transmission of sound by an elastic spherical shell is considered when it is subject to an incoming monochromatic planar wave. It is aimed to cancel the sound scattering using combinations of multi-pole sources located at the centre of a shell filled with compressible fluid. Assuming linear acoustics and structural dynamics, exact solutions are derived for total elimination of the sound scattering for three cases: a free-space, near a hard ground or near a free-surface, where in the last two cases it is assumed that the incoming wave propagates normal to the interface to maximize sound reflection back unto the source of the incoming wave. An elastic spherical shell of 1 m radius embedded in water and filled with air or oil is analysed to show the dominance of low-mode numbers for frequencies of less than 10 kHz and thus demonstrate the ability of this approach to damp acoustic scattering by means of low-order multi-poles inside the shell. Contour and mode distribution plots are also given and analysed.

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Scattering of a plane acoustic wave by a spherical elastic shell near a free surface

Cited by 31 publications

References 5 publications

Scattering of Plane Waves by a Rigid Sphere in an Acoustic Quarterspace

Scattering of Plane Waves by a Rigid Sphere in an Acoustic Quarterspace

Acoustic Radiation From a Pulsating Spherical Cap Set on a Spherical Baffle Near a Hard/Soft Flat Surface

Sound Scattering by an Elastic Spherical Shell and its Cancellation using a Multi-pole Approach

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