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-   -   [ICEM] Problem with volume mesh in ICEM CFD (https://www.cfd-online.com/Forums/ansys-meshing/92152-problem-volume-mesh-icem-cfd.html)

 kolapoasafa September 3, 2011 16:12

Problem with volume mesh in ICEM CFD

Can anyone please tell me how to carry out boolean operation with ICEM CFD? I have used GAMBIT previously, but trying to switch to ICEM. I understand ICEM is a surface based modeler, but I was thinking there might be a way around it.

My geometry is made up two concentric pipes, in which fluid flows between the inner and outer pipes known as the annulus. I wish to me render flow through the annulus by subtracting the inner pipe from the outer to form a single annular volume, then use a volume mesh with good refinement towards the walls.

Please i need help really fast. You can also refer me to the exact part of the ICEM CFD tutorial guide where an example of similar volume meshing can be found.

Thank you.

 stuart23 September 4, 2011 01:57

This is easier than you might think. Because ICEM is a surface modeller, all you need to do is create a volume that is fully enclosed by surfaces. This can be done as follows.

1) You must create lines between all of the intersecting surfaces. For surfaces in different parts, you will need to use the intersect surfaces tool to create the lines.

2) You must build your topology to make sure that ICEM has the correct connections between lines and surfaces. To check if the geometry is OK, right click on "lines" in the model tree and tick "colour by count". The lines should all become red to indicate that they are associated to surfaces on each side. If the lines are not all red, Increase your build topology toloerance and rerun the build topo.

3) Create a Material Point in the volume which you want to analyze. You can create more than one material point if you want to analyze more than one volume. ICEM will now only mesh the volume that the material point lies within. All other volumes enclosed will not be meshed, or their mesh will be discarded during the flood fill for Octree.

Note: It is not necessary to delete all other lines, points and surfaces that do not make up the enclosing geometry of your volume. When you export the mesh to your solver, ICEM only sends the mesh, and not the geometry. If there are no mesh elements on the excess geometry, It will not show up in your solver.

I hope this makes some sense. It is not very logical at first, you must understand that ICEM does not "know" what a volume is, it only knows points, lines and surfaces. It can however work out what is inside a set of closed surfaces, and what is outside a set of closed surfaces. Using this method, you should be able to tell it what "volume" you want meshed.

Stu

 esukem September 16, 2011 03:54

Hi Stu

So I have created an aerofoil and now a volume box to enclose the mesh from Catia.

Meshing the aerofoil was easy enough but not sure I understand where to begin.

I have imported the Catia V4 CAD file and its just a box. Do I have to mesh that seperatly to the aerofoil or together prior to unloading to the solver?

Cheers

James

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