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Old   March 2, 2012, 10:16
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Hi all
what will be the consequences if we are using a mesh with y+=5-30 using SST kw in fluent 13 at 4 deg and 12 deg angle of attack? and what will be the consequences if we are using the same mesh at same conditions using Realizable k-e model?
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Old   March 2, 2012, 11:42
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any body comment please.........
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Old   March 3, 2012, 12:35
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Far where r u lost?? you are lot of experience in this field.......
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Old   March 3, 2012, 15:09
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Quote:
what will be the consequences if we are using a mesh with y+=5-30 using SST kw in fluent 13 at 4 deg and 12 deg angle of attack? and what will be the consequences if we are using the same mesh at same conditions using Realizable k-e model?
The results should be similar at 4 and 12 deg for the y+ = 1 and 5-30 if there is no separation. But may start to deviate for y+ 10-30 in comparison to y+ = 1 and 5-10 if separation occurs. According to claim made for the automatic wall treatment it should give you same result for y+ upto 100. But in reality it is not true. If needed I can send you the papers regarding this issue.
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Old   March 3, 2012, 22:08
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Thank you very much Far for your concern, I really appreciate it. Yes papers would have been great help to me, please mail me at yasirforfriends@yahoo.com and by separation you just mean flow separation or you mean stall. Actually in my case, there is flow separation at 12 degree AOA but the wing is not stalling. What exactly you are talking about?
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Old   March 3, 2012, 23:10
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Quote:
Originally Posted by cfd seeker View Post
by separation you just mean flow separation or you mean stall. Actually in my case, there is flow separation at 12 degree AOA but the wing is not stalling. What exactly you are talking about?
I mean separation and for massive separation/stall better model would be the Differential Reynolds stress model, DES and/or LES. As you know, RANS models assume that the turbulence is isotrpic.

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Old   March 4, 2012, 05:33
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So it means even if at 12 degree AOA, wing is not stalling but we have to have wall y+ =1-10 to properly capture the physics of the flow and to get good estimate of CL and CD values right?
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Old   March 4, 2012, 05:44
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So it means even if at 12 degree AOA, wing is not stalling but we have to have wall y+ =1-10 to properly capture the physics of the flow and to get good estimate of CL and CD values right?
Yes, It is true based on the published results.

But to be sure for your case, you need to run the case with at least two y+ values or probably three i.e. y+ = 1, 10 and 30 for such extreme condition.

Rule of thumb is not meant for the final solution, it just guide you to the destination with minimum hassle, otherwise to be confident, you have to still make some checks for your case.

Also you need to ensure that boundary layer contains at least 10-15 nodes for automatic wall treatment.

I am sending you relevant Journal papers, in order to gain more insight to what I am referring.
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Old   March 4, 2012, 05:49
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thanks alot Far for your concern. Kindly mail me that papers, i have given yahoo id in the above posts
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Old   September 21, 2012, 10:38
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Quote:
Originally Posted by Far View Post
Yes, It is true based on the published results.

But to be sure for your case, you need to run the case with at least two y+ values or probably three i.e. y+ = 1, 10 and 30 for such extreme condition.

Rule of thumb is not meant for the final solution, it just guide you to the destination with minimum hassle, otherwise to be confident, you have to still make some checks for your case.

Also you need to ensure that boundary layer contains at least 10-15 nodes for automatic wall treatment.

I am sending you relevant Journal papers, in order to gain more insight to what I am referring.
Dear Far,

May you please send me the papers you've discussed above?
My E-mail is syavash_azna@yahoo.com
Tnx in advance.
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Old   September 21, 2012, 12:08
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Dear Far,,,,

I would appreciate your advise

I don't want to bother you, but...

Could you give me the paper please?

That paper seems very useful for my investigation

My e-mail adress is hdkam@pknul.ac.kr
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Old   September 21, 2012, 12:13
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Originally Posted by cartman View Post
Dear Far,,,,

I would appreciate your advise

I don't want to bother you, but...

Could you give me the paper please?

That paper seems very useful for my investigation

My e-mail adress is hdkam@pknul.ac.kr
pls confirm your email address
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Old   September 21, 2012, 12:29
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pls confirm your email address
My E-mail address is syavash_azna@yahoo.com

tnx again.
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Old   September 22, 2012, 14:27
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Old   September 22, 2012, 14:31
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I am getting this error

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Delivery to the following recipient failed permanently:

hdkam@pknul.ac.kr

Technical details of permanent failure:
DNS Error: Domain name not found
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