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Old   December 23, 2004, 19:53
Default Turbogrid and Negative volume
  #1
Ali
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hello everyone, I know that this is a repeated question. But I can not solve the problem of negative volume at Turbogrid. I have always negative volume and moving the points donot help (takes a lot of time and finally negative volumes). I also want to change the number of blocks at the shroud without hanging the nubmer at hub. Thank you for help. Happy holiday.. Ali
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Old   December 24, 2004, 02:03
Default Re: Turbogrid and Negative volume
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deLuther
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I found for myself that I can get better mesh form ICEM as fast as from TurboGrid...maybe even faster - less blocks - less headache...
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Old   December 24, 2004, 09:00
Default Re: Turbogrid and Negative volume
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Ali
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Thanks Luther, Does ICEM work with turbomachines? Ali
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Old   December 24, 2004, 09:23
Default Re: Turbogrid and Negative volume
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Reemull
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Go to the Template pull down menu and then try flipping your topology and profile. You'll need to rearrange you points afterwards - however just do it roughly. Then check your grid for negative volumes. If you no longer have negative volumes go back in and tidy up your points.

That's how I generally solve the problem.

Roy
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Old   December 24, 2004, 11:25
Default Re: Turbogrid and Negative volume
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Ali
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Thank you Roy, I just used Turbogrid from 1 week ago. I want to know what do you mean by "Template pull down menu" and would you explain how to perform this flipping..About arranging the point it takes a lot of time and does not work in my geometry. Ali
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Old   December 24, 2004, 12:18
Default Re: Turbogrid and Negative volume
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Reemull
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In the bar along the top of the Turbogrid, there is a button called Template. If you click on it it will produce a menu - which includes the two flipping options I mentioned.

Cheers

Roy
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Old   December 24, 2004, 16:24
Default Re: Turbogrid and Negative volume
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Ali
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Thanks Roy for quick response. I'm using Turbogrid 2.2 and there is no Tempelate button. What is the version that you use? Thanks again Ali
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Old   December 28, 2004, 18:47
Default Re: Turbogrid and Negative volume
  #8
Ali
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hello everyone again.. I'm using Turbogrid 2.2 and I get negative volumes. I moved control points and get no negative volume, but CFX solver says "there exists negative volume!!!" Anyone can help... Ali
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Old   December 31, 2004, 13:30
Default Re: Turbogrid and Negative volume
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Gang
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If you use TG 2.2, I highly recommend you to get TG 2.2.1. There is big improvement from 2.2 to 2.2.1. Which topology do you use? One thing I think may help is to inspect mesh from hub to shroud. By default, TG only shows grid on hub, shroud, and one span location. Sometimes, mesh on those surfaces may look perfect but problem still exists at other locations.
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Old   December 31, 2004, 18:54
Default Re: Turbogrid and Negative volume
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Ali
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Hello Gang, I use H-Grid and O-Grid for topology. I think the problem in my gemoetry that the blade have sharp cut. Around the tail and lead end the mesh intersect causing negative volume. I have TG 2.2 only. What you suggest? I also I can see a good mesh in BLADEgen how can I transfer it to CFX? Thanks.. Ali
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Old   January 1, 2005, 12:26
Default Re: Turbogrid and Negative volume
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Gang
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TG 2.2.1 has a new feature to handle sharp cut LE or TE. You should give it a try. It's very possible that your problem will be solved by TG 2.2.1.

Maybe BladeGen file can be imported into CFX-Pre directly. If not, you can convert BladeGen file into CGNS format in CFX launcher. CFX-Pre can read CGNS file.
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Old   January 2, 2005, 09:56
Default Thank you Gang
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Ali
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Thank you Gang for Reply and Happy NEw Year.. Ali
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