I use Blender to simulate and render fluids/liquids and it works perfectly for my purposes.
However the built in fluid physics as well as Flip Fluids addon and as well as the new Mantaflow engine do not support interaction of two or more fluids. For example if I want to mix liquid paints with 2 different colors or if I want to mix oil and water and then see how they are mixed and then separated because of different density.
So is there any preferably free but maybe commercial software that allows to simulate and render interaction between 2 or more fluids?