Assigning material to different parts
 

Hello guys, I am new to these things, so I have my doubts. My problem is while working on Tube-Fin Heat Exchanger, I have to assign different materials to tube, and fins. How do I do that?

You have to define the different materials first. Then you go to cell zone conditions and apply them to each zone.

In cell zone conditions, different parts are not being shown. Though I have defined new materials.
In cell zone conditions only "solid" is shown.

Ok so that means your mesh has only 1 zone. It needs to have more and you need to find a way to have more than 1 zone.

If you meshed it correctly, there should be boundaries between the tube and fins and you simply forgot to make it an interface in Fluent. Then all you have to do is split the mesh into two zones in Fluent. But usually this is not the problem.

Usually, the problem is you meshed both things in one go and now there is no distinct boundary between the two zones. If this is the case, you need to go back to the mesher.