two-pipe heat exchanger simulation
 

Hi,
I want to simulate a two-pipe heat exchanger by CFX. The diameter of inner pipe changes sinusoidally. The main purpose is to optimize heat transfer coefficient to get the least pressure drop by changing the inner tube. The question is how can I get the geometry of the inner tube so that it can be modified in the CFX?

This sounds like a parametric model in workbench. Have a look at the workbench tutorials. You might also want to look at DesignExplorer as an add-on to workbench.