A note on non-compact acoustic monopoles and dipoles
Abstract
The pressure and velocity field of a non-compact monopole with constant source strength within a sphere is derived. The analytical solution shows that the radiated sound power is strongly reduced for higher frequencies. The explanation for this phenomenon is a skin-effect reducing the radiating source strength. The pressure waves within the source region cannot be identified as being radiating sound waves. For certain frequencies the source becomes silent. Furthermore, by superposition of two sources a non-compact dipole is obtained which has a directivity which is different from that of a point dipole. It is also confirmed that on the surface of a source region a reverse energy flux can exist.
- Publication:
-
Journal of Sound Vibration
- Pub Date:
- September 1987
- DOI:
- 10.1016/S0022-460X(87)80070-6
- Bibcode:
- 1987JSV...117..519M
- Keywords:
-
- Acoustic Propagation;
- Dipoles;
- Monopoles;
- Sound Intensity;
- Spherical Waves;
- Acoustic Frequencies;
- Pressure Distribution;
- Sound Waves;
- Velocity Distribution;
- Wave Equations;
- Acoustics