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 instantaneous acoustic pressure.  Note the nodal lines (cones) at 22.5 and 44.5 degrees.
• Maximum positive pressure is blue, and minimum (negative) pressure is red; zero pressure is blue/green (the B&K color!)

The movie was created using MATLAB (Registered Trademark).