CFX Import from ANSA - Isolated Volumes

Yeats · May 20, 2016, 16:17

Hi everybody,

I would like to run an external aerodynamics simulation on a Formula Student car and rather then using the conventional Ansys mesher (which from my point of view is just terrible) I decided to generate the volume mesh in ANSA and import it afterwards to CFX.

I created a tet-mesh with prism layers to resolve the boundary layer and exported it as a cfx5 file.
After successful import of the mesh however, a boundary in the 2D regions shows up that represents the transition from the Tet-mesh to the prism layers. Obviously, if I leave this surface in the default region, I end up with isolated volumes (see attached screenshot). I have already tried assigning the same PID in Ansa to the entire volume mesh, without any success.

Does anybody have an idea how to bypass or solve that problem?
I'd greatly appreciate any advice!

ghorrocks · May 21, 2016, 06:14

It appears your mesh has one volume which is entirely tets (right to the wall) and another volume which is the prism layer. These volumes overlap. This is not an acceptable CFX mesh, you are going to have to go back to your mesher and regenerate it such that it is one contiguous mesh. While ANSYS mesher is not my favourite mesher either, it does not give you unusable meshes like that

Yeats · May 24, 2016, 10:05

Quote:

Originally Posted by ghorrocks

It appears your mesh has one volume which is entirely tets (right to the wall) and another volume which is the prism layer. These volumes overlap. This is not an acceptable CFX mesh, you are going to have to go back to your mesher and regenerate it such that it is one contiguous mesh. While ANSYS mesher is not my favourite mesher either, it does not give you unusable meshes like that

Of course, quite obvious actually!
Thanks for the quick reply and help

vangelis · June 1, 2016, 12:47

Just a quick comment
The problem occurred due to the fact that you used
Volumes>Define>AutoDetect without having the topcap of the layers
visible (possibly the visibility flag of FE-mod mesh was off)
so ANSA detected a volume right down to the base surface mesh
of the layers)

Whenever you use Detect volume ensure all is visible.

hope this helps

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
import autogrid mesh in cfx	Rike	Fidelity CFD	1	February 28, 2018 18:45
[OpenFOAM] Annoying issue of automatic "Rescale to Data Range " with paraFoam/paraview 3.12	keepfit	ParaView	60	September 18, 2013 03:23
[ICEM] Error on import in to cfx	jbritton	ANSYS Meshing & Geometry	1	May 19, 2010 11:56
Import Fan 3D Model - Workbench or CFX?	Stewart Long	CFX	2	October 28, 2008 04:05
Errors running allwmake in OpenFOAM141dev with WM_COMPILE_OPTION%3ddebug	unoder	OpenFOAM Installation	11	January 30, 2008 20:30

May 21, 2016, 06:14		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	It appears your mesh has one volume which is entirely tets (right to the wall) and another volume which is the prism layer. These volumes overlap. This is not an acceptable CFX mesh, you are going to have to go back to your mesher and regenerate it such that it is one contiguous mesh. While ANSYS mesher is not my favourite mesher either, it does not give you unusable meshes like that

June 1, 2016, 12:47		#4
vangelis Senior Member Vangelis Skaperdas Join Date: Mar 2009 Location: Thessaloniki, Greece Posts: 287 Rep Power: 21	Just a quick comment The problem occurred due to the fact that you used Volumes>Define>AutoDetect without having the topcap of the layers visible (possibly the visibility flag of FE-mod mesh was off) so ANSA detected a volume right down to the base surface mesh of the layers) Whenever you use Detect volume ensure all is visible. hope this helps