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September 10, 2013, 20:55 |
Holes in the prism layer
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#1 |
New Member
Alessandro
Join Date: Aug 2013
Posts: 4
Rep Power: 13 |
Hello everyone,
I have to do an unstructured tetra mesh of an entire airplane but it is giving me a lot of trouble. I'm using the bottom-up method, so surface mesh -> prism layer-> volume mesh. I need to create a prism layer that has a height of 2. What I'm trying to do is generate one single layer and after split it. But how you can check from the images below, near the winglet and in other parts of the plane, there are some holes. The geometry it's ok, all the lines are red. Winglet clean surface https://www.dropbox.com/s/zu32dm2vf3ykx2k/Immagine4.jpg Winglet 1: https://www.dropbox.com/s/p321b126ze0osnm/Immagine.jpg Prism layer over winglet: https://www.dropbox.com/s/1nt7lih02upoxkf/Immagine5.jpg cut plane Winglet: https://www.dropbox.com/s/quz5ujgpntfq6c3/Immagine6.jpg fin and fuselage: https://www.dropbox.com/s/8uk613raeq2u0zi/Immagine2.jpg Fin-fuselage-tail https://www.dropbox.com/s/jn6a7du7q7ifymq/Immagine3.jpg Prism Parameters: https://www.dropbox.com/s/5b4b85j9kjwafzw/Immagine7.jpg fort the smoothing options, I've just "max directional smoothing steps=3" and "first layer smoothing steps=1" I have also tryed to create a more layer at the same time, but it doesn't work. The same if I create the prism layer after the volume mesh 1. regarding the winglet, the problem should be that there isn't space enough to create a prism layer with a height of 2 (Indeed I tryed to create a PL with a height of 1 and it works). Is there a way to solve that problem or I have to modify the geometry, filling the little space between the vertical surface (winglet) and the orizontal ones (wing)? 2. Regarding the other parts of the airplane, any particular suggestions? Thank you. |
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September 11, 2013, 09:22 |
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#2 |
Senior Member
Stuart
Join Date: Jul 2009
Location: Portsmouth, England
Posts: 739
Rep Power: 26 |
I've used ICEM tetra/prism to mesh full aircraft geometies I would say the surface mesh at the winglet region is too coarse. I suggest making that finer and then floating the prism layers (i.e. set the initial height and total height to zero for a few layers) then split and redistribute. Make the prisms after making the volume mesh, the latter with the Delaunay (TGlib and Use AF options on). Remember to check and smooth the surface and volume mesh before making the prisms. Also you can save time with a smoothed volume mesh by setting the volume smoothing in the prisms menu to zero. Also you should switch on the auto reduction option in the prisms advanced options. I would ignore any target prism layer height (e.g. you say 2) and aim for making a mesh and running the CFD solution to check the yplus and resolution of the boundary layer. If you need improe yplus and boundary layer resolution from the CFD solution then alter the surface mesh (which controls the floating prisms) and the prisms split/redistribution.
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September 12, 2013, 05:26 |
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#3 |
New Member
Alessandro
Join Date: Aug 2013
Posts: 4
Rep Power: 13 |
hi siw, thank you for your answer
The fixed heigth comes from previous simulations that the person befor me did (I'm continuing him works, but on a very very similar geometry). Anyway I'll try to do how you said, hoping that it'll works. Thanks |
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September 12, 2013, 06:08 |
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#4 |
Senior Member
Stuart
Join Date: Jul 2009
Location: Portsmouth, England
Posts: 739
Rep Power: 26 |
You should look at this topic: http://www.cfd-online.com/Forums/ans...eneration.html.
PSYMN gives a hyperlink to a very useful ANSYS presentation for ICEM prism generation. I use this for guidance alot for my Fluent and CFX simulations. |
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