CFD Online Discussion Forums - Seperate fluid domains

I expect this is a bit of a stupid question, but I cannot find the answer in the Help or elsewhere on the web.

I am trying to use ANSYS to analyse the natural cooling of one of our Pump/motors during blackout conditions. The model has 3 separate fluid domains

1. Water in the pump
2. Water in the motor
3. Air outside of the motor

The fluids themselves do not meet, the heat transfer between them is through the pump and motor casings.

Best way to imagine the setup is two tin cans full of water, one on top of the other with the top one hot at time zero, I want to find the max temp that the bottom can reaches whilst the both cool in the air

The problem I am having is that it will only let me have 1 fluid in the model, If I change the properties for fluid 1 in the Air it changes in both the waters and vice versa, If I add another fluid I end up with an air /water mix in all the domains.

Could you please advise how to overcome this problem

Cheers

Phil