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Old   March 4, 2006, 02:26
Default meshing, any help is welcome
  #1
Richard
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Hi, i am stimulating a pump with 6 blade that has a airfoil profile. The thickness of the blade vary along the axial length and it is highly curvature since the blade angle changes along the axial length, following a parabolic relationship. So does that mean using the educational package of Ansys CFX 5.7.1 is not enough. I have try many time using angular resolution for the blade with very fine min edge but still the meshing run into error. If I require additional package, i need to justified it.I have create an cylindrical enclosure around the pump using a diameter slightly larger than the max radius of the pump. Then i froze the pump and cut it out of the enclosure, leaving only the fluid region behind. Since the surfae is very close, do i need to set the proximity option?

Thank, any advices and tips is welcome
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Old   March 5, 2006, 17:30
Default Re: meshing, any help is welcome
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Glenn Horrocks
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Hi,

Try CFX Bladegen. It is specifically designed to create meshes in rotating machinery.

Glenn Horrocks
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Old   March 5, 2006, 23:00
Default Re: meshing, any help is welcome
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TB
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I can't see why this problem can't be fixed in ICEMCFD. Are you using ICEMCFD for mesh generation?
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Old   March 5, 2006, 23:00
Default Re: meshing, any help is welcome
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Richard
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Thank for the help, but i am using the educational package, and do not have the fund for additional package
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Old   March 6, 2006, 17:27
Default Re: meshing, any help is welcome
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Glenn Horrocks
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Hi,

This sort of thing would definitely be easier on Bladegen and Turbogrid, but as TB says if ICEM is what you have (or even Workbench) you should still be able to do it. If angular resolution is not working, try defining a fixed mesh size in the regions of interest.

Glenn Horrocks
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Old   March 7, 2006, 03:30
Default Re: meshing, any help is welcome
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Richard
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I think the meshing is done by CFX-MESH2 in CFX 5.7.1. Is it the same as ICEMCFD? I trying using constant spacing but still could not work,the error messenge involve mesh spacing not resolved and unlapping. I guess unless i use very fine spacing which will create too many element, and considering I am only using a computer with 512 ram. I might not have the computing power in the solver. The blades all end with very narrow tip and pointed edges. Some of them have thickness of 0.2 mm only. Pls help me. I am really struck
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Old   March 7, 2006, 06:05
Default Re: meshing, any help is welcome
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TB
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Ha. I purchased license for Bladegen few years ago but I seldom touched it then. It took me a long time to understand how to work with Bladegen. For problem like this, ICEM should tackle it quite easily as well.

Richard: I think you're talking about the CFX-mesher (tetra mesh tool) appeared in Workbench. It's different from ICEMCFD (advanced meshing tool). I haven't worked with CFX-mesher for quite some time. Can't give any advice on that. Sorry.
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Old   March 7, 2006, 09:26
Default Re: meshing, any help is welcome
  #8
longbow
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Have you tried putting face or edge spacing control near blade tip and edge? Using them, you can have a locally fine mesh while keep overall mesh size in control. You can also turn on surface proximity.
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Old   March 7, 2006, 09:34
Default Re: meshing, any help is welcome
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Richard
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Ya, it is the one that come with the workbench. I try point control on the edge before but still cannot work. As for surface promity, that will result in even larger node size up to million as the gap between my blade and housing is very close, only 0.1 mm.I know a previous student who did the same stimulation using turbogrid and manage to keep the total number of node less than 30000. but i dun have the fund for the software. I suspect it might due to the fact that i am using external cad package( pro-e) which require even finer meshing. I try IGES and Parasolid format, both dun work
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