[Asghari_M]

Hi all;

I'm solving fluid flow & heat transfer for a coil with a circular cross section according to the following attached figure. Just As anybody observes, this pattern has two returns (two couple elbows ). My question is that if I can model this problem by a two dimensional model or I have to model this example by a three dimensional one. The boundary conditions are same for every cross section. If your answer is ok, Please lead me how to consider this configuration.

Also,Suppose , a gas within the coil is my model being heated by a liquid fluid. Which boundary condition is suitable for outlet Temperature?
Dirichlet or neumann ,d()/dn=0.0 or another one?
What's your opinion?
What about should we take for other outlet boundary conditions,too ? For example, the pressure or velocity.

Also, consider a semi-cylinder surrounds this coil. How can I mesh this three dimensional pattern by subtracting this semi-cylinder from coil?
Actually, which mesh type with which quality can be used for this problem?
My email is mehdiasgh@gmail.com for any further information.

Thanks a lot for any help.

Drawing4.jpg