Radiation from a circular plane rigid baffled piston:

• Fluid is ambiant air.  The piston is at the origin, and has a radius a=30 cm.
• The frequency is 1825 Hz, corresponding to ka=10. (corresponds to Figure 7.4.5 in K&F, 4th ed).
• Shown here is the time averaged acoustic intensity.
• The length of the arrows is proportional to the fourth power of local intensity amplitude.

The figure was created using MATLAB (Registered Trademark).