Open Access

ARTICLE

Three Dimensional Wave Scattering by Rigid Circular Pipelines Submerged in an Acoustic Waveguide

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1 Department of Civil Engineering, University of Coimbra, 3030 Coimbra, Portugal

Computer Modeling in Engineering & Sciences 2001, 2(1), 49-62. https://doi.org/10.3970/cmes.2001.002.049

Abstract

The Boundary Element Method (BEM) is used to compute the three-dimensional variation pressure field generated by a point pressure source inside a flat waveguide channel filled with a homogeneous fluid, in the presence of infinite rigid circular pipelines. The problem is solved in the frequency domain, using boundary elements to model the pipeline and an appropriate Green's function to simulate the free surface and the rigid floor of the channel. Because of the 2 ---1/2 ---D geometry of the problem, the separation of variables has been used, and the solution at each frequency is expressed in terms of waves with the varying wavenumber, k_z. Time responses at different points in the space domain are computed by applying an inverse (Fast) Fourier Transform, using a Ricker pulse as the dynamic excitation source.
Simulation analyses using this idealized model are then used to study the patterns of wave propagation in the vicinity of these inclusions, following waves with different apparent wave velocities along the z axis. The amplitude of the wavefield in the frequency vs. axial-wavenumber domain is presented, allowing the position of the inclusions to be recognized and identified, providing a basis for the development of non-destructive testing and imaging methods.

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