[Hus]

Hey guys, I just wanted to start off by saying that I'm really new to ICEM, and CFD in general, so I apologize in advance if there is a simple solution to this.

I have been given a 2D unstructured mesh file of a jet nozzle grid, and have been asked to create this into 3D on ICEM, at first I used the rotational method but realised that this would not work for a 3D simulation. So, I was recommended to use a multiblock meshing technique (H-O type) to create the 3D mesh. I was told to use a cartesian block in the centre and along the centreline, then create a cylindrical mesh around this block which covers the nozzle lip and the outer part of the domain, however I am struggling to do this as I have never used ICEM before, and I havn't been able to find any online tutorials.

If anyone could point me to a tutorial or give me some information on how I could achieve this I would be extremely grateful.

[Gweher]

Hello Hus,

Well, the easiest to start with ICEM is to go through the tutorials. There are more than 10 default tutorials in the Ansys documentation. When you start ICEM just go under Help tab > Tutorial manual.

Get familiar with the blocking approach, in 2D first and then in 3D. There are a lot of "How to" videos on ICEM, Far has a great channel with a lot of interesting material, you should have a look https://www.youtube.com/watch?v=JxUnEMbGBL4

You can still rotate the 2D blocking and end up with degenerated elements at the center line. Then slice the created blocking around the center line with an offset and create your O-grid from there. Or you can also start directly from a 3D blocking and slice it with a similar approach.

Have fun

[Hus]

Originally Posted by Gweher

You can still rotate the 2D blocking and end up with degenerated elements at the center line. Then slice the created blocking around the center line with an offset and create your O-grid from there. Or you can also start directly from a 3D blocking and slice it with a similar approach.

Thank you for your reply, the tutorials from Far seems to be helpful, however I do not have any geometry or blocking available to me. All I have is the 2D unstructured mesh file. This is the reason I've been having trouble following tutorials online as most have the blocking to work with. Would the process still be similar in this case?

[Gweher]

Well you can easily create the blocking, starting from scratch. The only thing that you need is the geometry file. You then create the blocking under the blocking tab, first icon and > insert blocking.

Here is a similar topic on the forum, also talking about a 3d nozzle geometry. It is not a 360° so they use an Y-grid or quarter O-grid to mesh the center line but it is really useful to get you started :
http://www.cfd-online.com/Forums/ans...s-meshing.html

[Hus]

Thank you, once again, for your help. I'm sorry to bother you yet again, I do not have a geometry file to use to start the blocking from scratch. I have found a block file of the mesh I have shown in my first post. But this gives me an error saying that there is no geometry file available and will lead to problems in hexa mesh generation, and I'm not entirely sure this looks correct, as there are a bunch of warnings when it loads up...(first two images)

I also noticed an option to "load blocking from unstructured mesh", so I rotated the unstructured mesh through the extrude mesh option. Then loaded the blocking through the option previously mentioned. Im not sure if this is suitable for a 3D simulation, however, (last image). Also the blocking generated by this method is different to do the blocking file previously mentioned. I have uploaded a few screen shots of them below.

[Gweher]

You can use your method for the blocking but on the first image you need to deselect the "VORFN" part as it contains the surrounding blocking that isn't use to mesh your actual domain.

To understand a little bit more about the blocking approach you should look at the ICEM basics, here is a nice video that explains the main concepts (done by Far):

https://www.youtube.com/watch?v=Jk6t5kx6KF0

Having a blocking is one of the 2 elements that you need to re-generate a mesh, the other one is the geometry file to which you'll need to associate your blocking. If you don't have both of them you wont be able to generate a new mesh. So you should either look at a .tin file (ICEM geometry file) or re-create the geometry you want to mesh.

[Hus]

Thank you very much for your help once again. Sorry I have not replied earlier, I have been reading up further on ICEM. I have managed to recreate the geometry and block it in 2D, then rotate the blocking. I am now trying to create an O-Grid. I have attempted to do it as you have said in your first post by splitting it with an offset, however the mesh does not form properly or does not get affected by it. Is it required to block the geometry in 3D, instead of rotating it from the 2D blocking?
I have attached some images below. Any further advice would really be appreciated.