### ASA 127th Meeting M.I.T. 1994 June 6-10

## 4aEA11. Theory and construction of a toroidal waveguide with active walls
(the acoustitron).

**Christopher C. Lawrenson
**

**
F. Douglas Shields
**

**
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*Natl. Ctr. for Phys. Acoust., Coliseum Dr., University, MS 38677
*

*
*
The analytical solution for axisymmetric sound propagation in a viscid
fluid-filled infinite tube with rigid walls was first worked out by Kirchhoff
and later Lord Rayleigh. This work has been extended to the case of a tube with
a controlled surface wave at the fluid boundary. Theoretical calculations show
that when the surface wave travels at the intrinsic speed of sound of the
fluid, the ratio of the axial to the radial particle velocity amplitude is
infinite. A prototype of such a system has been build using a toroidal tube to
simulate an infinite propagation path. Theoretical calculations and preliminary
results will be presented. [Work supported by ONR.]