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September 10, 2015, 05:20 |
problem in concept of y plus?
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#1 |
Senior Member
Hydreaulic structures
Join Date: Sep 2012
Posts: 283
Rep Power: 14 |
hi to all
i read help of cfx about near wall modeling, As it was written, two way exist for modeling flow near the wall: 1-wall function approach that using of scalable wall function that used for all models based on epsilon equation. 2- The Low-Reynolds-Number method that is suitable for models based on omega equation, in fact it has automatic near wall treatment in order to reduce Requirements of resolution. whether yplus for models are based on epsilon equation cant located in viscous sublayer? whether it induce To need to yplus< 0.2 in low reynolds number? unfortunately i dont find specific values for yplus for variety of turbulence models and only discussed about low-Reynolds number k-epsilon & k-w in help cfx, i find your mentions about this in previous topic as following: SST can handle any y+. k-e should be >11 k-omega should be <1 RSM should be >11 if using wall functions or anything if automatic. The question that came to me is that: as your mentioned , sst can handle with any yplus, in my simulation y+ value is too large, But I did was sensitivity study in mesh, whether really amount does not matter and What is the reason it? There is no specific limit? my impression is that it Due to the use of automatic near wall treatment. i opologize for long discussion thanks a lot for any comment kind regards hamid |
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September 10, 2015, 06:09 |
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#2 | |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,703
Rep Power: 143 |
Quote:
The maximum value allowable for y+ comes down to a mesh size sensitivity, and the error you are happy to have in the simulation. |
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September 11, 2015, 03:04 |
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#3 |
Senior Member
Hydreaulic structures
Join Date: Sep 2012
Posts: 283
Rep Power: 14 |
hi dear glenn
as your mentioned, your guess about my question is correct and I mean it was. thanks a lot |
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