[ICEM] Deleting VORFN blocks in ICEM CFD

Sai Swaroop · October 14, 2011, 08:53

Hi,

When the 'Merge Vertices' option was used to merge, an unnecessary split appeared in some of the blocks. Also the split made the blocks into triangle. This problem does exist no matter where and which vertices are merged (the split is coming on the same set of blocks irrespective of merge location and vertices).

To solve the above problem, I tried to delete the blocks from VORFN in ansys ICEM CFD. Although it shows the blocks are deleted permanently, the blocks in VORFN does exist and the above problem persists.

Can anyone please help me on this regard.

Thanks..

PSYMN · October 15, 2011, 10:41

Sorry, I don't understand your problem... maybe a pic would help.

I can tell you that if you delete all the VORFN blocks, new VORFN blocks are created... The new blocks may have a different topology than the original. It is usually only a good idea to Delete VORFN blocks if you want to disconnect live blocks that are being connected by VORFN blocks.

Sai Swaroop · October 16, 2011, 03:27

@Simon: Thanks a lot.

I have been going through your replys on various posts and now I think I understand the problem although I dont know the solution.

Sorry I cant post any pic as it is confidential. I know it is very very difficult to answer any problem without looking into it but I cant get any data from the PC (admin has blocked it). I have explained the problem below (the only option left) and give more trouble to you (really sorry for that).

The geometry we are trying to mesh is a complex one (fighter jet). We adopted a bottom up approach and used 'Extrusion' option to generate new blocks and maintain connectivity. But 'Extrusion' started giving error 'Extrusion Failed' for some reason (blocks being complex and twisted I guess). So we created the block using 'Extrusion' wherever we got it, say in 'part A', split it, separated it from original part (Part A) by deleting the connecting block and merged it with other block in another part, say 'part B'. We knew that deleted block goes to 'VORFN' but what we didnt know was the connectivity is still maintained even after deleting the block (sending it to VORFN). This could be causing the problem. I tried deleting the VORFN blocks (there are 1075 blocks in VORFN

) permanently but the blocks remain (although it shows blocks are deleted permanently) and the problem persists.

We have extruded blocks from a part, split it, delete the middle block and merged it with block of other part at many many locations and now we are in Deep Shit

. Also if we split one block we are getting unnecessary splits in blocks that dont seem connected (probably connected through VORFN blocks). Deleting the VORFN blocks permanently doesnt seem to remove the connection as the problem re-appears. Is there a way out??

Help us if you can. Once again sorry for not being able to post any pic and yet ask your help.

Thanks a lot...

Sai Swaroop · October 17, 2011, 03:12

Hi I forgot. The meshing we are doing is structured 3D mesh

PSYMN · October 17, 2011, 14:15

It is tough to help without seeing, but generally, I don't do much bottom up anyway... usually just a few blocks here or there. I have never really tried to do a whole model that way...

Perhaps you are taking hexa down an un-paved road.

As for deleting the VORFN blocks, they are always created again (Hexa needs them as a concept), but perhaps not as they were. Again, I use deleting of VORFN blocks very sparingly...

Sai Swaroop · October 18, 2011, 11:26

@Simon: Thanks for the help. We overcame the problem by recreating the blocks after deleting the problematic ones permanently.

October 14, 2011, 08:53	Deleting VORFN blocks in ICEM CFD	#1
Sai Swaroop New Member Sai Swaroop Join Date: Oct 2011 Location: Bangalore, India Posts: 11 Rep Power: 15	Hi, When the 'Merge Vertices' option was used to merge, an unnecessary split appeared in some of the blocks. Also the split made the blocks into triangle. This problem does exist no matter where and which vertices are merged (the split is coming on the same set of blocks irrespective of merge location and vertices). To solve the above problem, I tried to delete the blocks from VORFN in ansys ICEM CFD. Although it shows the blocks are deleted permanently, the blocks in VORFN does exist and the above problem persists. Can anyone please help me on this regard. Thanks..

October 15, 2011, 10:41		#2
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Sorry, I don't understand your problem... maybe a pic would help. I can tell you that if you delete all the VORFN blocks, new VORFN blocks are created... The new blocks may have a different topology than the original. It is usually only a good idea to Delete VORFN blocks if you want to disconnect live blocks that are being connected by VORFN blocks. __________________ ----------------------------------------- Please help guide development at ANSYS by filling in these surveys Public ANSYS ICEM CFD Users Survey This second one is more general (Gambit, TGrid and ANSYS Meshing users welcome)... CFD Online Users Survey

October 17, 2011, 14:15		#5
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	It is tough to help without seeing, but generally, I don't do much bottom up anyway... usually just a few blocks here or there. I have never really tried to do a whole model that way... Perhaps you are taking hexa down an un-paved road. As for deleting the VORFN blocks, they are always created again (Hexa needs them as a concept), but perhaps not as they were. Again, I use deleting of VORFN blocks very sparingly... __________________ ----------------------------------------- Please help guide development at ANSYS by filling in these surveys Public ANSYS ICEM CFD Users Survey This second one is more general (Gambit, TGrid and ANSYS Meshing users welcome)... CFD Online Users Survey

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October 16, 2011, 03:27		#3
Sai Swaroop New Member Sai Swaroop Join Date: Oct 2011 Location: Bangalore, India Posts: 11 Rep Power: 15	@Simon: Thanks a lot. I have been going through your replys on various posts and now I think I understand the problem although I dont know the solution. Sorry I cant post any pic as it is confidential. I know it is very very difficult to answer any problem without looking into it but I cant get any data from the PC (admin has blocked it). I have explained the problem below (the only option left) and give more trouble to you (really sorry for that). The geometry we are trying to mesh is a complex one (fighter jet). We adopted a bottom up approach and used 'Extrusion' option to generate new blocks and maintain connectivity. But 'Extrusion' started giving error 'Extrusion Failed' for some reason (blocks being complex and twisted I guess). So we created the block using 'Extrusion' wherever we got it, say in 'part A', split it, separated it from original part (Part A) by deleting the connecting block and merged it with other block in another part, say 'part B'. We knew that deleted block goes to 'VORFN' but what we didnt know was the connectivity is still maintained even after deleting the block (sending it to VORFN). This could be causing the problem. I tried deleting the VORFN blocks (there are 1075 blocks in VORFN ) permanently but the blocks remain (although it shows blocks are deleted permanently) and the problem persists. We have extruded blocks from a part, split it, delete the middle block and merged it with block of other part at many many locations and now we are in Deep Shit . Also if we split one block we are getting unnecessary splits in blocks that dont seem connected (probably connected through VORFN blocks). Deleting the VORFN blocks permanently doesnt seem to remove the connection as the problem re-appears. Is there a way out?? Help us if you can. Once again sorry for not being able to post any pic and yet ask your help. Thanks a lot...

October 17, 2011, 03:12		#4
Sai Swaroop New Member Sai Swaroop Join Date: Oct 2011 Location: Bangalore, India Posts: 11 Rep Power: 15	Hi I forgot. The meshing we are doing is structured 3D mesh

October 18, 2011, 11:26		#6
Sai Swaroop New Member Sai Swaroop Join Date: Oct 2011 Location: Bangalore, India Posts: 11 Rep Power: 15	@Simon: Thanks for the help. We overcame the problem by recreating the blocks after deleting the problematic ones permanently.