[Daniel_Khazaei]

Hello to all,

I have a problem with extrude surface mesh tool in ICEM CFD.
I have created a structured mesh for my fluid domain.
Now I need to extrude the surface mesh in order to get a solid wall mesh.

I have done the followings:

1) Converting structured mesh to unstructured.

2) delete volume mesh an unnecessary boundary meshes.

3) In this step I have the desired surface mesh. (att)

4) Now when I extrude the surface mesh for a specific thickness, generated mesh collapses at the bifurcation region.

I think extrude normal method is the cause. Is there any other method?


Best wishes

[kad]

It seems that your specified thickness is too large. In regions where the original elements are already pretty close to each other the mesh has not enough space for extrusion. This leads to collision. E.g. has the prism mesher a auto reduction option to avoid this kind of problem. So if possible, reduce the thickness for extrusion.

Extrude by element normal should be fine. I think none of the other extrusion methods will work for this. If reversing the extrusion diretion is an option for you, give it a try.

[Daniel_Khazaei]

Originally Posted by kad

It seems that your specified thickness is too large. In regions where the original elements are already pretty close to each other the mesh has not enough space for extrusion. This leads to collision. E.g. has the prism mesher a auto reduction option to avoid this kind of problem. So if possible, reduce the thickness for extrusion.

Extrude by element normal should be fine. I think none of the other extrusion methods will work for this. If reversing the extrusion diretion is an option for you, give it a try.

Well I need the thickness of 0.5 mm for the wall. It only produces good results with the thickness of 0.1 mm.
Surface mesh is the wall of fluid domain, I think reverse extrude is not an option.
I need something like the attached image:

[diamondx]

so what you want is another alternative for extruding that surface mesh. Have you tried extruding using the prism function !

[Daniel_Khazaei]

Originally Posted by diamondx

Try extruding using the prism function !

Would u please give me more details on how to do it?

Best wishes,

[Daniel_Khazaei]

I have seen in a video tutorial from "pyformex" software that extrusion direction at bifurcation region is not normal to the surface (att), is it possible in ICEM?

[diamondx]

When you delete your volume mesh, generate prism layer from your surface mesh. it is the third tab under compute mesh...

[Daniel_Khazaei]

Originally Posted by diamondx

When you delete your volume mesh, generate prism layer from your surface mesh. it is the third tab under compute mesh...

Thanks for the help.

I think something is wrong with my setup, I need to generate them outward and prism layers are distorted near the boundaries.

[diamondx]

ok, the distorsion is caused by the feature not well developped I guess. To be honest, I knew it existed but never tried it... sorry about that. I guess one way to extrude them outward is to place your geometry in a box, and place a body part outside of your geometry and inside the box , so the prism are generated in the opposite direction.

[Daniel_Khazaei]

Originally Posted by diamondx

ok, the distorsion is caused by the feature not well developped I guess. To be honest, I knew it existed but never tried it... sorry about that. I guess one way to extrude them outward is to place your geometry in a box, and place a body part outside of your geometry and inside the box , so the prism are generated in the opposite direction.

Thank you very much for the support. With the distortion problem at the boundaries, I don't think extruding outward/inward is going to fix my problem.

I have tried to use Shell feature in SolidWorks in order to get a wall thickness of 0.5 mm. Even there, maximum acceptable thickness is near 0.2 mm. So I guess this is problem of my geometry.

Do you have any other suggestions to get solid wall in these cases?

Best Wishes.

[Daniel_Khazaei]

Is there any way to smooth extruded mesh in ICEM?

I have tried to smooth it, however weird things happened after smoothing which I thing it is due to the lack of geometrical constraints on the extruded mesh. (There are no surfaces for the top and sides parts and the mesh is not bounded)

[kad]

Originally Posted by Daniel_Khazaei

Is there any way to smooth extruded mesh in ICEM?

I have tried to smooth it, however weird things happened after smoothing which I thing it is due to the lack of geometrical constraints on the extruded mesh. (There are no surfaces for the top and sides parts and the mesh is not bounded)

You are right. The smoothing function needs surfaces otherwise the mesh will get distorted.

An other approach is to use scaling factors. Try to scale your geometry and then subtract the original geometry from the scaled one.

One question: What do you need the thin walls for? E.g. for heat transfer you can define a wall thickness in Fluent.

[Daniel_Khazaei]

Originally Posted by kad

You are right. The smoothing function needs surfaces otherwise the mesh will get distorted.

An other approach is to use scaling factors. Try to scale your geometry and then subtract the original geometry from the scaled one.

One question: What do you need the thin walls for? E.g. for heat transfer you can define a wall thickness in Fluent.

I answer the last question first

I am planning to perform a fluid-structure interaction.

----------

about scaling:

Do you think it is applicable to my geometry? the geometry is not aligned on the principle direction. I have tried scaling before, but the scaled one usually coincides with the original geometry.

Thanks for your help and support.

[kad]

I really can not say as I am not a CAD expert. I know Designmodeler comes with a tool to deal with thin surfaces.