Help a novice to solve a simple liquid-in-solid problem

[bintu]

Hi everybody.
I'm totally new to Elmer at the moment. It's been only for a few days that I'm trying to understand the basis.
I'm using GID as mesher but maybe I'm driving to another one in the future.
I'm using ThinkDesign as 3d environment.

Project: I'd like to study the thermal flow in a solid cooled by a water pipe.

what I do:
- export in stp, stl, igs formats. For example, the solids I export are 1) a cube with an hole 2) a cylinder representing water. The cylinder is exactly matching the hole in the cube.
- import in GID the solids: cube in layer 0 and tube in layer 1 (although I suppose Gid has a bug here, importing only to layer 1 so one has to move objects to other layers in order to prevent them to be overwritten).
- adjust the surfaces and volumes to make 2 separate solids: cube with hole and tube the external surface of the tube and the hole surface should now collapse or not? Should I mantain one surface only?
- meshing: 3d or 2d? In the curved pipe example, 2d mesh is used.
- problem type: elmer -> set data, materials, volumes. My goal is to assign a material (ie steel) to body and another one (ie water) to the cooling liquid. Thanks to different layer I succeed to assign them.
- problem type: elmer -> set data, costraints, surfaces: I assign costraints according my wanted boundaries: 1) steel body (all surfaces but the inner hole one) 2) cube inner hole surface 3) one base of the cilynder 4) the other base surface 5) the lateral cilynder surface : total of 5 costraints. Is it correct?
- save project and calculate
- importing in Elmer: open mesh--> select folder of previoously calculated Gid problem
- elmer crashes. Either does crash importing the 2 solids having a common surface, or it does import only one solid, even if I exported both by GID.

Have you guys some advice/tutorials/step by step guide to import a geometry consisting of a solid with a hole in which i can make a liquid flow to refrigerate it?
I can't just understand where am I wrong !!

Thank you so much.

[escolano]

Sorry, but I am only expert on GiD, I don't use Elmer.

I had a very old and simple GiD-Elmer problemtype,and it can write the mesh and some boundary conditions in a Elmer format (of years ago, maybe has changed)

I don't know what is the exact mesh formats supported by Elmer, that nowadays has its own GUI.
You must read its documentation.