CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   CFX Importing (http://www.cfd-online.com/Forums/cfx/84789-cfx-importing.html)

ad281 February 8, 2011 18:31

CFX Importing
 
I generated a 2D mesh (1 element thick), in ICEM CFD.
When I import it to ANSYS-CFX, I am unable to define any boundaries.
When I det the solver to ANSYS-CFX in the solver tab within ICEM, I am unable to define any boundaries either.
I would appreciate any help with this.

RossFS February 8, 2011 22:50

FYI: Ideally, post this in the ANSYS CFX -> Meshing forum
you have to generate the boundary locations in ICEM CFD by making parts (if my memory is correct) with each one representing a boundary location.

ad281 February 9, 2011 02:27

I did this.
It won't allow me to create the boundary conditions from the parts in output when I select ANSYS-CFX as the solver.

CfdLunak February 11, 2011 05:35

I am not ICEM user, but CFX-Pre allows you to create surface for boundary condition from physical boundary via edit mesh.

shahpar73 February 11, 2011 23:31

No need defining BC in "Output". It is best to do an ICEM tutorial available in help.
Once you complete the mesh, add it to the part and then right click on "Part" in the "Model Tree" and select create part.
Select each surface to create boundary locations. The associated mesh to the surface will automatically be assigned to that boundary location. After this you can "Output".

Josh February 12, 2011 05:16

Make sure to be careful when defining parts, etc. in ICEM. If you're doing a 2D simulation in CFX, it's easiest to save your ICEM project as a Fluent V6 file and import it to Pre, which will automatically extrude it.

Here's a good tutorial on setting up parts for a 2D airfoil:

http://www.youtube.com/watch?v=tYrbS...eature=related

ad281 February 12, 2011 07:31

Yeah, I actually have been using that tutorial as a guide all along ha. Thanks for that tip though. I'l try it out.
I managed to get it working though. I extruded the 2D mesh 1 element thick. In the extrude sidebar, I chose to name the extruded sides WALLS and extruded surface SYMMETRY.
Then I hid everything except WALLS, chose create new part, then selected the blocks on the relevant wall face as my INLET, OUTLET etc.

ad281 February 12, 2011 10:12

I've another issue now, when I create the mesh, it has about 450,000 elements.
When I run the simulation in CFX-Solver, i see that it is using over 800,000 nodes. When I compare this with a mesh of similar size made in CFX-Mesh, the number of nodes roughly corresponds to the number of elements.
I'm guessing that this is the reason that the ICEM model is using up twice as much RAM to compute.
Can anybody shed some light on why this is happening?

Josh February 12, 2011 15:47

CFX effectively doubles the amount of nodes because it extrudes your 2D mesh to 3D (since it cannot perform 2D simulations).

ad281 February 14, 2011 18:41

I'm not quite doing it like that... When I extrude the mesh 1 element thick in CFX-Mesh, I get around 400,000 elements with 400,000 nodes.
When I create a 2D in ICEM, extrude it 1 element thick, I see in solver that it has 400,000 elements with 800,000.
My issue is as to why this is happening, and how I can have it running on the same amount of nodes as CFX-Mesh.

ghorrocks February 15, 2011 06:26

How are you doing the counts?

The 400k elements and 400k nodes does not sound possible for a 1 element thick geometry. Should be 800k nodes. I suspect CFX-Mesh is just counting the 2D nodes and that is not correct.

If you count them in CFX-Pre or CFD-Post (or in the mesh section of an output file) they will tell you the true node count.

ad281 February 15, 2011 09:13

Here's an example.
http://img96.imageshack.us/img96/4992/84910136.jpg

When I do the same thing, except with an ICEM, mesh, the number of nodes doubles. Also about doubling the RAM required.

ghorrocks February 15, 2011 16:46

I would need to look at your mesh to work out what is going on here.


All times are GMT -4. The time now is 18:26.