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Impeller mesh with Turbogrid and Yplus results

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Old   November 29, 2013, 12:21
Default Impeller mesh with Turbogrid and Yplus results
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Hello everybody,

i'm using CFX 14.5.7 to simulate one stage of a centrifugal compressor. I used Turbogrid to mesh the impeller passage. Attached is the minimum errors that i could achieve playing with factors inside mesh data.

The simulation reached acceptable value for residual RMS error (less than 10^-4), but Yplus is more than 300.

Is there anyone who has suggestions or comments to improve Yplus result?
I did not use tip clearance on shroud because i saw that by introducing a clearance at shroud the errors in the mesh increase. But i would like to ask if is reasonable to model the clearance in the mesh and if someone has experience of meaningful results.

Thanks for any help!
Attached Images
File Type: jpg mesh data.jpg (65.4 KB, 32 views)
File Type: jpg stg3_Yplus.jpg (35.0 KB, 31 views)
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Old   November 30, 2013, 05:51
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Glenn Horrocks
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Do not simply assume that a big y+ means your simulation is bad. You should do a mesh sensitivity check and find out whether it is a problem or not.

And also do not assume your convergence is acceptable either. You should check that as well.
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Old   October 14, 2014, 11:23
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Hi Nabu,

I am doing a similar simulation and developed the mesh for a passage using Turbogrid but am stuck after the single passage analysis. I have completed the single passage analysis but my work requires to model a full stage centrifugal compressor. Can you please help me with this. Is this done in ICEM CFD or can it be doen directly in CFX-Pre.

Also, I have an inlet pipe geometry which I need to connect to the full stage mesh. Do I need to develop a united geometry in design modeller or would it be fine if I model it separately and then import it to CFX-pre after meshing in ANSYS meshing tool?

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