Render and animate two different colored fluids in a pipe

Hello!

Any ideas or tips on what would be the easiest and fastest way to render two liquids, or something that looks like liquids, in a pipe. It should look like one liquid pushes the other out of the pipe.

I have some ideas myself, but I have a hard time coming to a conclusion on which method’s the best or easiest.

It does not have to be realistic. It’s more intended to visualize a concept.

Put two fluid particle emitters with different colors in pipe.