[Guangyu]

Hi, there,

First, thanks for your kind help if you're reading this thread.

I'm carrying out CFD prediction of hull resistance. The problem I've got is I have two identical hull surfaces in the Regions node after 'Assigning Parts to Regions'.

However, the part from Boolean Subtract shows only one hull surface and six domain surfaces. In other words, I've got one more hull surface identical to the original one because of 'Assigning Parts to Regions'.

Can anyone have any idea what's the possible reasons for this problem and what can be done to solve this?

I really appreciate your suggestions and comments.

Guangyu

[ping]

you have done something silly in the assign parts to regions, and can probably simply delete one of the hull boundaries from the region but make sure that each boundary in the region is connected to the correct surface in your parts

[Guangyu]

Originally Posted by ping

you have done something silly in the assign parts to regions, and can probably simply delete one of the hull boundaries from the region but make sure that each boundary in the region is connected to the correct surface in your parts

Hi, Ping,

Thanks for your suggestion. I'll have a try to see if I encounter further problems. Will have further discussions with you.

Cheers

Guangyu Shi

[Guangyu]

Originally Posted by ping

you have done something silly in the assign parts to regions, and can probably simply delete one of the hull boundaries from the region but make sure that each boundary in the region is connected to the correct surface in your parts

Hi, Ping,

Unfortunately, I met further problems when generating volume mesh after simply deleting the replicate hull surface. I'm thinking probably I need to repair the geometry first before going for mesh generation. Do you have further comments on this issue?

Thanks a lot for your help.

Guangyu

[ping]

are you doing a full hull analysis or half a hull with a symmetry plane?
where did you hull surface come from and was it imported into parts or 3d-cad? either way you need to check it after import to ensure it has no holes, double surface etc using the surface checking and repair tools in 3d-cad or parts.

[Guangyu]

Originally Posted by ping

are you doing a full hull analysis or half a hull with a symmetry plane?
where did you hull surface come from and was it imported into parts or 3d-cad? either way you need to check it after import to ensure it has no holes, double surface etc using the surface checking and repair tools in 3d-cad or parts.

Hi, Ping,

I'm working on a catamaran, and only one demihull is used for simulation. I'll try to repair the geometry first as you suggested and let you know the result.

Thanks again.

Guangyu

[Guangyu]

Originally Posted by ping

are you doing a full hull analysis or half a hull with a symmetry plane?
where did you hull surface come from and was it imported into parts or 3d-cad? either way you need to check it after import to ensure it has no holes, double surface etc using the surface checking and repair tools in 3d-cad or parts.

Hi, Ping,

I've used the Surface Repair Tool to check my geometry, apart from hundreds of 'Face Quality' and 'Face Proximity' problems which I think wouldn't cause many serious issues, there is one 'Non-manifold Edge', which I believe is the root of my problem. Do you have any idea how to remove the non-manifold edge in Star CCM+, or do you suggest to fix it using the CAD software before exporting the geometry file?

Thank you so much for your help.

Cheers

Guangyu