[Dena]

Dear all,
I am trying to model a shell and tube heat ex-changer in Ansys (am using Ansys R15.0, Academic). It is 7m long and 2m diameter shell, with 800 tubes of 25mm diameter. The inside of the tubes has hot air, while the shell side has cold oil. I want to get the temperature gradients for the air and the oil flowing through it.

I developed the model in Ansys by first extruding a cylinder, and then slicing it to form the tubes and the air parts.

However, the geometry can not be meshed. Am i doing it wrongly?

Please advise me on how best i can best model the behaviour of this heat exchanger, any assistance will be very much appreciated.