Problem with zero thickness surfaces/baffles – mesh imported from ANSA.

Tudor_M · December 29, 2015, 09:06

Happy Holidays!

I’m having a weird problem solving a case (external aero) with mesh imported from ANSA (exported in Fluent .msh file). In pre each baffle (0 thickness) comes with its copy entity (shadow) but that not all. After case is solved:

With all 0 thickness surfaces (including shadows) being assigned wall property air can penetrate this walls! Now that got puzzled because even if I would want to I still don’t know how can I make a wall property to not behave like a wall. Same I heard from local ANSYS support guy (very experienced with CFX in particular).
My question is – have anyone experienced anything similar? Is there a way around it (ANSA mesh to CFX)? I don’t really want to learn icem cfd or whatever – enough time spent in ANSA creating this mesh on fairly complex model. If I don’t find proper export/import solution than I will go back to cad level and add thickness to surfaces (major pita with very comples surfaces)
Thanks
Ted

ghorrocks · January 2, 2016, 00:21

Have you tried defining the thin surfaces as walls? You might need to define both sides as walls.

Tudor_M · January 2, 2016, 13:43

Yes - all the baffles (including shadows) were assigned WALL property. In fact - talking to experienced CFX guy (works for ansys russia) he says that even if he wanted to he doesn't know how to make an entity with wall property be transparent to airflow.

I solved the problem on CAD level (added thickness) but it was a PITA to do ))) But it works now.

Thanks
Ted

Opaque · January 4, 2016, 11:31

I am confused with your description. What does mean a WALL being transparent to air ? Either is a wall, or it is not. It cannot be both ways.

Once the mesh is imported, and a boundary condition assigned to the faces and its shadows, did you mark those faces as WALL, or INTERFACE ?

Tudor_M · January 4, 2016, 14:26

I am confused as well. So was ansys tech. support. I did assign to faces and shadows WALL property I'll dig out some screenshots to ilustrate.

vangelis · January 16, 2016, 06:25

Any conclusions on this?

December 29, 2015, 09:06	Problem with zero thickness surfaces/baffles – mesh imported from ANSA.	#1
Tudor_M New Member Tudor Miron Join Date: Dec 2015 Posts: 24 Rep Power: 10	Happy Holidays! I’m having a weird problem solving a case (external aero) with mesh imported from ANSA (exported in Fluent .msh file). In pre each baffle (0 thickness) comes with its copy entity (shadow) but that not all. After case is solved: With all 0 thickness surfaces (including shadows) being assigned wall property air can penetrate this walls! Now that got puzzled because even if I would want to I still don’t know how can I make a wall property to not behave like a wall. Same I heard from local ANSYS support guy (very experienced with CFX in particular). My question is – have anyone experienced anything similar? Is there a way around it (ANSA mesh to CFX)? I don’t really want to learn icem cfd or whatever – enough time spent in ANSA creating this mesh on fairly complex model. If I don’t find proper export/import solution than I will go back to cad level and add thickness to surfaces (major pita with very comples surfaces) Thanks Ted

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January 2, 2016, 00:21		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Have you tried defining the thin surfaces as walls? You might need to define both sides as walls.

January 2, 2016, 13:43		#3
Tudor_M New Member Tudor Miron Join Date: Dec 2015 Posts: 24 Rep Power: 10	Yes - all the baffles (including shadows) were assigned WALL property. In fact - talking to experienced CFX guy (works for ansys russia) he says that even if he wanted to he doesn't know how to make an entity with wall property be transparent to airflow. I solved the problem on CAD level (added thickness) but it was a PITA to do ))) But it works now. Thanks Ted

January 4, 2016, 11:31		#4
Opaque Senior Member Join Date: Jun 2009 Posts: 1,804 Rep Power: 32	I am confused with your description. What does mean a WALL being transparent to air ? Either is a wall, or it is not. It cannot be both ways. Once the mesh is imported, and a boundary condition assigned to the faces and its shadows, did you mark those faces as WALL, or INTERFACE ?

January 4, 2016, 14:26		#5
Tudor_M New Member Tudor Miron Join Date: Dec 2015 Posts: 24 Rep Power: 10	I am confused as well. So was ansys tech. support. I did assign to faces and shadows WALL property I'll dig out some screenshots to ilustrate.

January 16, 2016, 06:25		#6
vangelis Senior Member Vangelis Skaperdas Join Date: Mar 2009 Location: Thessaloniki, Greece Posts: 287 Rep Power: 21	Any conclusions on this?