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DavidCarlsson January 20, 2012 05:34

Hexa meshing a STL file in aerospace industry
As background, Iím working in the aerospace industry. I have some experience in ICEM but then only hexa meshing. We have quite strict requirements on the mesh quality and we normally use low Reynolds mesh. A further explanation on our requirements can be found in the question jola posted on the ďMain CFD Forum/Meshing complex white-light/GOM based STL modelsĒ.

Now to the question. I have received a GOM measured model. This model is quite complex and consist of the entire geometry on the part in question, shafts, flanges and so on. Since Iím only interested in the wet surfaces (where the flow is going) I need to clean the geometry from all other surfaces. My overall idťe is to read in the STL file Iíve got from GOM in ICEM -> clean it up -> Sort the different surfaces in different groups-> add inlet and outlet -> mesh in hexa -> run it in Fluent.

My first attempt was to read in the STL as geometry and using the build topology option. This didnít work at all, the curves and points that was created was useless.
After reading on this forum Iíve loaded the STL file as a mesh instead. I then use the flood fill command and trying to separate the mesh surfaces from each other. This works fairly well. However, I donít really have any sharp edges so I have to work with angel as small as 1-2 degrees. Is there any better way of separate the surfaces a part? Please be quite specific because I donít find my way that good in the menus of ICEM. Furthermore, when using flood fill Iíve got hole in the mesh. Iím the using close mesh holes but the need to take on hole at the time, is there any way of fixing/closing all holes in one operation?
After separating the mesh surface my plan is to use the mesh to facet command. Iíve then have, hopefully, some different surfaces. However, the intersection between two surfaces (for example the hub and vane) will not sharp nice looking curve but a rather ďwobblyĒ curve. Iíve would have preferred a nice looking curve in order be able to mesh the hexa better. Is there any good way of achieving this?

Basically what I need is information on how to modify the stl file geometry/mesh.

Iíve would be very happy for all trick and tips you can give me.

Thanks David

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