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

5aPA9. Acoustics of fluid conveying elastic structures.

Michael A. Grinfeld

Andrew N. Norris

Dept. of Mech. and Aerosp. Eng., Rutgers Univ., Piscataway, NJ 08855-0909

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.]