The instructions on this page will guide you in resimulating a liquid simulation to add foam and splashes. This process is useful when doing a simulation that requires a low amount of secondary (foam, splash or mist) particles relative to the volume of the liquid. Resimulation is a convenient option when you have the motion of the fluid nailed down and you're only looking to add some extra detail.
To follow along this tutorial, you can either download the provided project files, go through the Creating a Simple Liquid Simulation tutorial or modify your own custom liquid simulation setup.