It is my understanding that in the latest version of Caedium it is possible to use two different fluids in the same simulation. The example "CFD Simulation of a Pitot Tube and Manometer" use both water and air.

In the electronics cooling example, would it be possible to define the heat sinks consisting of a secondary fluid with a very high viscosity? This way the secondary fluid's heat conduction property can be set equal to a real heat sink. Then simulation would include important heat distribution between heat producing components and the liquid cooled surface.