[dotapro]

Hi all,
I'm trying to mesh fine mesh around the ship as shown in the picture. However, the meshing was failed whereby my meshing method is listed as below:
Body sizing (0.1m, soft) - Fine Mesh
Body sizing (1m, soft) - Coarse Mesh
Body sizing (3m, soft)- Very Coarse Mesh

Can anyone lend their hand on this matter?

[hwet]

Where is the mesh? Where are the errors? What would you understand if I posted the same question?

[dotapro]

The meshing failed as it just hang there without continue to mesh. Any suggestions for that?

[hwet]

Yes that is because theres just too much meshing to do for you PC. What are the dimensions of your geometry? What are the dimensions of your ship, what are you actually trying to simulate?
Do you actually need that whole region around your ship.

The ships will be tet meshed, but you must put inflation on the surfaces, for the region around your ships use hex mesh that will greatly reduce the cell count and make it quicker to build the mesh and for the later simulations as well.

But this problem is basically because you are trying to use too fine a mesh which you PC isnt just capable of doing. Mesh in parts mesh the ship first then the outer region or vice versa.

[dotapro]

Thanks for your reply. My dimensions of ship could be 262 m x 42 m x 81 m (LXWXH). My focus could be external flow around the ship (mainly concern on upper side of ship). Is it proper I only consider upper side of ship (half of the ship )?

[hwet]

I recently meshed a 10mx3m cylindrical geometry and ended up with 5 million cells, with your size the mesh is going to be way to big, you must also reduce the details on the ships. Could you post a closeup of the ship, also increase the angle of curvature to say 64 degrees and see how it goes, then you can increase or decrease it later.

[Kapi]

Hi Dotapro,

1. Reduce your ship size to half by slicing
2. Remove small parts which has no affect on flow
3. Try to have geometry with only outer surface, and remove small faces and edges
4. Yes you can simulate upper half of ship only if you you need to see external flow only in that area.
5. Give body/edge/face sizing in specific area where you want to see flow.
6. As suggested by hwet, increase angle of curvature

Please post closeup of your ship for better understanding.

Hope it helps

Cheers
KAPI

[dotapro]

Thank you very much for your reply. I have try to mesh it accordingly but it is still hang there. There are some parts of it require to be porous region. Is it correct if I group it as share topology (share) in space claim? How to mesh it effectively if my study does not allow scarification of ship bottom part(it requires modelling of whole ship)? I have attached my ship image.

[hwet]

We cant tell by looking at a picture of the ship, what the actual geometry you made in your CAD package is. You should atleast post a picture of the geometry you import in Ansys meshing (a close up).

Just to give you some idea, these ropes and small hooks on your ship if you have all of these in the CAD geometry, it is going to be an extremely big mesh. You should remove the parts which do not effect the flow over the ship.

Also divide your ship into smaller parts and mesh them independently to see where the trouble happens.

[Kapi]

Hi DotaPro,

For simulation purpose you have to use/change your design in a very simplified manner. You need a very simple model which depicts your ship.
Dont use your CAD Production model for simulation purpose.
Just think of you ship made of cylinder and cubes and model you ship. several smaller cubes(cabin and stuff) sitting on bigger cube( ship base)
Remove all the small components which you think will not effect on air flow
Divide you model in parts wrt to material as well.
Example: your porous region (cubes) should be a separate part.
Your base (cube) should be a separate part
You chimney (cylinder) could be a separate part

Make you simplified model and post here.

Hope it helps

Cheers
KAPI