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-   -   Double Walled Pipe Boundary (http://www.cfd-online.com/Forums/fluent/110178-double-walled-pipe-boundary.html)

dahvqaz December 5, 2012 08:23

Double Walled Pipe Boundary
 
Hey All,

This is my first post on this forum! I have been working on a project for the last few days and I have become a little frustrated. I can model a very very simplified version of my problem but once I attempt what I'd like to do I struggle a lot. Ok so here's the information I can provide you.

I want to model fluid flow through a double walled pipe - except the outer pipe is closed at the bottom. The fluid inlet is the top of the smaller pipe, the fluid travels to the bottom of the smaller pipe (approx. 10m) when it reaches the bottom it hits the closed end of the larger pipe and is forced up the large pipe (on the outside of the small pipe, within the large pipe, annulus is the proper term for this space).

I guess an analogy of this would be if you dug a cylindrical hole 11m deep and put a 10m long cylindrical pipe almost to the bottom. You then pump fluid through the pipe and its circulated outside the pipe (within the hole) back to surface.

How I created this geometry is a solid 10m long, 10cm thick sweep with an outer diameter of 2m. I created a fluid 11m long sweep to model the fluid within the pipe. I then created a fluid 11m long thin surface sweep (outer thickness 1m) to model the fluid outside the pipe.

I assigned the inlet to be the top surface of the inner fluid and the outlet to be the top surface (doughnut) of the outer fluid.

MY PROBLEM: I dont know how to get my fluid path to follow the path I want it to (ie. down and then back around to surface). Specifically I dont know how to merge the fluid surfaces at the bottom 1m of the hole. Right now when I mesh its treated as two boundaries.

Can anyone point me in the right direction. If you need further details (images, etc) let me know.

ghost82 December 5, 2012 10:09

Can you post a sketch please?

RodriguezFatz December 5, 2012 11:14

Also: What software do you use for creating the geometry and what software do you use for meshing?


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