I am trying to model a small section of a car radiator with fluid flowing through the tubes and air flowing past the outside of the tubes. I can do both separately but i would like to have them both simulated at the same time, so i can see the cooling effect of the air on the fluid in the tubes. Below is a picture of the section, there is two tubes running vertically either side of the fins. Does anyone know if it is possible to simulate both fluid through the tubes and air flow past the tubes/fins at the same time? Any help would be great.