The Ejs Group Velocity model displays the time evolution for the superposition of two traveling waves of similar wave numbers and frequencies.  The simulation allows an arbitrarily superposition of two waves for the study of group and phase velocity.  The amplitude, wave number, and angular frequency of each wave can be changed via text boxes.  You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item.  

Ejs Group Velocity model was created using the Easy Java Simulations (Ejs) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_ehu_waves_group_velocity.jar file will run the program if Java is installed.  Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models.  Additional Ejs models for wave motion are available.  They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Please note that this resource requires at least version 1.5 of Java (JRE).