Acoustic scattering from arbitrarily shaped multiple bodies in half‐space: Method of moments solution

1992 ◽  
Vol 91 (2) ◽  
pp. 652-657 ◽  
Author(s):  
Sadasiva M. Rao ◽  
B. S. Sridhara
Keyword(s):  
Half Space ◽  
Method Of Moments ◽  
Acoustic Scattering ◽  
Space Method

Application of Method of Moments to Acoustic Scattering From Fluid Filled Cylinders Using Three Different Formulations

1995 ◽  
Author(s):  
S. P. Sun ◽  
P. K. Raju ◽  
S. M. Rao
Keyword(s):  
Integral Equation ◽  
Cross Section ◽  
Method Of Moments ◽  
Acoustic Scattering ◽  
Arbitrary Cross Section ◽  
The Body ◽  
Equation Formulation ◽  
Integral Equation Formulation ◽  
Equivalent Problems ◽  
Field Integral

Abstract In this work, we present three different formulations Viz. The pressure field integral equation formulation (PFIE), the velocity field integral equation formulation (VFIE), and the combined field integral equation formulation (CEDE) for solving acoustic scattering problems associated with two dimensional fluid-filled bodies of arbitrary cross section. In particular using the boundary conditions on the surface of the body, two equivalent problems, each valid for the outside and inside regions of the scatterer, are derived. By properly selecting the associated equations for these equivalent problems, the three different formulations are derived. The PFIE, VFIE, and CFIE are then solved by approximating the cylindrical cross section by linear segments and employing the method of moments. Further, it is shown that the moment matrices generated by the PFIE and VFIE are ill-conditioned at resonant frequencies of the cylinder, whereas the CFIE generates a well-conditioned matrix at all frequencies. The solution techniques presented in this work are simple, efficient and applicable to truly arbitrary geometries. Numerical results are presented for certain canonical shapes and compared with other available data.

Determination of Acoustic Scattering From a Two-Dimensional Finite Phononic Crystal Using Bloch Wave Expansion

2014 ◽  
Author(s):  
Jason A. Kulpe ◽  
Michael J. Leamy ◽  
Karim G. Sabra
Keyword(s):  
Internal Pressure ◽  
Half Space ◽  
Pressure Field ◽  
Phononic Crystal ◽  
Acoustic Scattering ◽  
Bloch Wave ◽  
Two Dimensions ◽  
Integral Theorem ◽  
Wave Expansion ◽  
Kirchhoff Integral

In this study the acoustic scattering is determined from a finite phononic crystal through an implementation of the Helmholtz-Kirchhoff integral theorem. The approach employs the Bloch theorem applied to a semi-infinite phononic crystal (PC) half-space. The internal pressure field of the half-space, subject to an incident acoustic monochromatic plane wave, is formulated as an expansion of the Bloch wave modes. Modal coefficients of reflected (diffracted) plane waves are arrived at via boundary condition considerations on the PC interface. Next, the PC inter-facial pressure, as determined by the Bloch wave expansion (BWE), is employed along with the Helmholtz-Kirchhoff integral equation to compute the scattered pressure from a large finite PC. Under a short wavelength limit approximation (wavelength much smaller than finite PC dimensions), the integral approach is employed to calculate the scattered pressure field for a large PC subject to an incident wave with two distinct incident angles. In two dimensions we demonstrate good agreement of scattered pressure results of large finite PC when compared against detailed finite element calculations. The work here demonstrates an efficient and accurate uniform computational framework for modeling the scattered and internal pressure fields of a large finite phononic crystal.

scholarly journals Inverse acoustic scattering problem in half-space with anisotropic random impedance

2017 ◽  
Vol 262 (4) ◽  
pp. 3139-3168 ◽  
Author(s):  
Tapio Helin ◽  
Matti Lassas ◽  
Lassi Päivärinta
Keyword(s):  
Half Space ◽  
Scattering Problem ◽  
Acoustic Scattering
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