Speed:

Resolution:

Instructions:  
To draw barriers, pause or clear the simulation, then click and drag. To add pressure, start the simulation, then click and drag. The speed slider scales the momentum of the particles to change the speed of the wave. Changing the quality slider will change the resolution and reset the simulation.

Theory:  
The simulation is based on the Huygens-Fresnel principle which states that every point on a wavefront is the source of another wavefront. This causes the wave to expand in a spherical shape. This also causes diffraction, the bending of waves around corners. This can be demonstrated in this simulation.