[GAMBIT] Error when Subtracting Volumes

ldavis · August 25, 2010, 22:03

Hi,

I have created a 3D wing in Gambit, which has a volume for the boundary layer (BL) surrounding it, as well as a larger domain. Previously, I was able to properly subtract the BL from the domain, and the wing from the BL. But, I needed to change the BL shape for a better mesh. Since then, I have received the error message below when my BL was too small (I assume since when I made it bigger, the message went away). But, now, the same error message is appearing for the subtraction of the BL from the domain. My domain is much larger so this shouldn't be a problem.

The error message is: ACIS error 80030: inconsistent face-body relationships.

The root of the wing is at the edge of the domain and the BL. But, it appears to be correctly aligned, so that should not cause problems. I also used nurbs to create the BL edges, but again, I do not know why that would affect it.

If anyone is aware of what this error message could mean, I would appreciate the help.

Thanks!

-mAx- · August 26, 2010, 03:34

I don't understand why you are trying to substract the BL.
You should substract the wing (solid) from you outer domain.
Then the BL can be created around your wing (but it is not a substract operation, there is a special tool for that).
Of course as alternaive you can also split your domain around your wing for meshing the BL.

ldavis · August 26, 2010, 08:48

Thanks for the reply. I have tried to use the Boundary Layer Mesh tool. But, I have experienced several problems for this shape, and it does not provide a good boundary layer mesh. I could be going about it wrong. I have tried to mesh the TE or LE and then use the 3D mesh view icon, but none of the allowed direction are not correct to go around the wing. I have also tried to mesh the upper and lower surface, which resulted in the root having a reasonable BL. Then, I tried to use the 3D mesh view, but that tried to mesh the full domain instead.

The wing is also not a straight wing; it has a sweep angle, dihedral angle, winglet, and tapered chord. So, I have resorted to create this second domain for the BL. I have used this method before, but for a cube. So, I think the problem lies on the boundary layer where the domain, BL and wing have a face.

If you have any other suggestions, please let me know.

Thanks!

-mAx- · August 26, 2010, 08:51

Then ok you can try handling the BL by spliting your volume with a surface surrounding your wing.
but you need to do a split, not a substraction

ldavis · August 26, 2010, 11:23

Thanks, I have never used the domain split method before. But, I will give it a go. However, the error message does appear with that as well. Through trial and error, it turns out that my domain and BL are not perfectly aligned. They were as far as I could tell, but I have the plane they are on is slightly angled which is causing me a headache. So, I will keep working on aligning them better.

Thanks for the help!

August 25, 2010, 22:03	Error when Subtracting Volumes	#1
ldavis New Member LDavis Join Date: Aug 2010 Posts: 5 Rep Power: 16	Hi, I have created a 3D wing in Gambit, which has a volume for the boundary layer (BL) surrounding it, as well as a larger domain. Previously, I was able to properly subtract the BL from the domain, and the wing from the BL. But, I needed to change the BL shape for a better mesh. Since then, I have received the error message below when my BL was too small (I assume since when I made it bigger, the message went away). But, now, the same error message is appearing for the subtraction of the BL from the domain. My domain is much larger so this shouldn't be a problem. The error message is: ACIS error 80030: inconsistent face-body relationships. The root of the wing is at the edge of the domain and the BL. But, it appears to be correctly aligned, so that should not cause problems. I also used nurbs to create the BL edges, but again, I do not know why that would affect it. If anyone is aware of what this error message could mean, I would appreciate the help. Thanks!

August 26, 2010, 03:34		#2
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	I don't understand why you are trying to substract the BL. You should substract the wing (solid) from you outer domain. Then the BL can be created around your wing (but it is not a substract operation, there is a special tool for that). Of course as alternaive you can also split your domain around your wing for meshing the BL. __________________ In memory of my friend Hervé: CFD engineer & freerider

August 26, 2010, 08:51		#4
-mAx- Super Moderator Maxime Perelli Join Date: Mar 2009 Location: Switzerland Posts: 3,297 Rep Power: 41	Then ok you can try handling the BL by spliting your volume with a surface surrounding your wing. but you need to do a split, not a substraction __________________ In memory of my friend Hervé: CFD engineer & freerider

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August 26, 2010, 08:48		#3
ldavis New Member LDavis Join Date: Aug 2010 Posts: 5 Rep Power: 16	Thanks for the reply. I have tried to use the Boundary Layer Mesh tool. But, I have experienced several problems for this shape, and it does not provide a good boundary layer mesh. I could be going about it wrong. I have tried to mesh the TE or LE and then use the 3D mesh view icon, but none of the allowed direction are not correct to go around the wing. I have also tried to mesh the upper and lower surface, which resulted in the root having a reasonable BL. Then, I tried to use the 3D mesh view, but that tried to mesh the full domain instead. The wing is also not a straight wing; it has a sweep angle, dihedral angle, winglet, and tapered chord. So, I have resorted to create this second domain for the BL. I have used this method before, but for a cube. So, I think the problem lies on the boundary layer where the domain, BL and wing have a face. If you have any other suggestions, please let me know. Thanks!

August 26, 2010, 11:23		#5
ldavis New Member LDavis Join Date: Aug 2010 Posts: 5 Rep Power: 16	Thanks, I have never used the domain split method before. But, I will give it a go. However, the error message does appear with that as well. Through trial and error, it turns out that my domain and BL are not perfectly aligned. They were as far as I could tell, but I have the plane they are on is slightly angled which is causing me a headache. So, I will keep working on aligning them better. Thanks for the help!