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cheye October 1, 2012 15:46

Internal Wall Definition (2D)
I am trying to simulate flow through two concentric pipes using an axisymmetric 2D simulation (not periodic).

The first difficulty is that the inner pipe is only half as long as the outer and neither end extends to the inflow nor outflow of the whole domain. Thus, I need to define an internal wall zone, but I would like to define it as infinitely thin and avoid removing material from the domain. I have tried sketching lines and making them "edges" of a sort, but they do not appear in the Meshing software and I am left with a simple rectangular domain.

The second issue may be solved in the same way, but I need to define a region within the inner pipe in which to apply a fan model in FLUENT. I understand how to implement the fan model, but it requires defining a zone in the geometry.

If someone can help me with imposing non-intrusive lines on the geometry for meshing purposes, I would greatly appreciate it. Thank you!

diamondx October 1, 2012 22:49

what software are you using to mesh ? if you are using ICEM CFD. just draw your cylinders with creating fluid domain inside because it's a surface based mesher.
i have never tried internal wall in ansys meshing, but i think you forgot to create a surface out of your edges. you do that in concept menu ---> surface from edges. give it a try...
If it doesn't work i will try it my self and see how it works

Antanas October 2, 2012 06:37

Maybe you should use two domains and interfaces between them?

PSYMN October 2, 2012 10:07

Right, create surfaces from the curves... You will want two bodies and you can combine them into a multibody part if you want conformal mesh.

You can select edges and create Names Selections for the internal wall boundary conditions...

cheye October 4, 2012 15:04

Thank you for your help! I ended up projecting the edges onto the rectangular domain which I had to set to "frozen".

If you are willing to help me on another issue, I would greatly appreciate it.

My geometry is as I would like, but I am unable to mesh a 2D domain with inflations. I have many walls in the domain now and grid clustering in the boundary layer regions. I have tried specifying "sizing" on some edges, but that does not increase the number of cells anywhere except on the surface.

Can you tell me how I can cluster an unstructured mesh in a 2D domain?

PSYMN October 4, 2012 16:49

Look up 2D inflation in the help...

// Meshing User's Guide // Local Mesh Controls // Inflation Control

Scroll down and look for the notes specific to 2D inflation.

It is a little odd in the way you need to select the 2D body and the edges for inflation, but once you see how, you shouldn't have any trouble with it.

Volumeoffluid November 18, 2013 12:20

Hi all,
i have two bodies(frozen in DM) and when i go to fluent and use VOF model
there is ONE DOMAIN....i want two domains and i dont know how i can define them before go to fluent....
i want one with with water..
thank you in advance!

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