### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 5aPA9. Acoustics of fluid conveying elastic structures.

**Michael A. Grinfeld
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Andrew N. Norris
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*Dept. of Mech. and Aerosp. Eng., Rutgers Univ., Piscataway, NJ 08855-0909
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Acoustic waves are considered that are propagating in a layered structure
consisting of elastic layers with ideal fluid moving between them. This is a
simple model of a fluid-filled porous medium. First discussed is the dependence
of the dispersion curves on the relative velocity of the fluid and on the
material and geometrical parameters of the constituents. Dispersion relations
for a periodic layering are derived explicitly. Different asymptotic limits can
be obtained, which reduce to known solutions for interfacial acoustical wave
motion in the presence of flow. The main focus of this talk is the possibility
of instabilities triggered by the moving fluid in the layered system. The role
of such acoustical instabilities in nonlinear dynamics of poroelastic
fluid-filled media is discussed. This effect can be viewed as a generalized
flutter phenomenon, made possible by the permeability of the pore space. [Work
supported by ONR.]