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Pseudo interface waves observed at the fluid/porous-medium interface. A comparison of two methods
K N van Dalen1, G G Drijkoningen, D M J Smeulders
1Faculty of Civil Engineering and Geosciences, Department of Geotechnology, Delft University of Technology, Stevinweg 1, Delft 2628 CN, The Netherlands. k.n.vandalen@tudelft.nl
The Journal of the Acoustical Society of America
|May 17, 2011
Summary
The study clarifies how pseudo-Rayleigh (pR) and pseudo-Stoneley (pSt) waves at fluid/porous interfaces are analyzed. Different branch cut methods yield distinct results for wave properties, impacting their interpretation.
Area of Science:
- Geophysics
- Acoustics
- Wave Propagation
Background:
- Pseudo-Rayleigh (pR) and pseudo-Stoneley (pSt) waves arise at fluid/porous-medium interfaces.
- The interpretation of these waves depends on the chosen branch cut method in the slowness plane.
Purpose of the Study:
- To investigate the relationship between wave poles and branch cut choices for pR and pSt waves.
- To determine how different methods affect the computation of wave properties.
Main Methods:
- Far-field Green's functions computed using vertical branch cuts (Method I).
- Far-field Green's functions computed using hyperbolic branch cuts (Method II).
- Analysis of pole locations and loop integral contributions in each method.
Main Results:
- Method I: pR and pSt poles obey radiation conditions; interface waves are captured by pole residues.
- Method II: Loop integrals contribute to pR-waves; pSt-wave capture depends on pole location on Riemann sheets.
Conclusions:
- Phase velocity and attenuation of separate pseudo interface waves are computed from pole location in Method I.
- In Method II, these properties must be extracted from the full response, especially when pSt-poles migrate Riemann sheets.
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