Superposition of a plane wave and a spherical wave:

• Fluid is ambiant air.  The plane wave travels from left to right (in positive-x direction).
• Spherical wave emitted at the origin by pulsating sphere of radius a=5 cm.
• The frequency is 2000 Hz.  Both waves have unit complex amplitudes, and are perfectly synchronous.
• Velocity vector length proportional to velocity amplitude (no adjustment).  20 x 20 grid points.

The movie was created using MATLAB (Registered Trademark).