y plus and standard wall functions
Hi guys,
i use k-ε with standard wall functions. The values of y+ are between 25 and 308. I tried different grids but i can't achieve the range that fluent suggests 30<y+<300. It will be better if i have a coarser mesh, in order to have a y+ range from 30 to 320, approximately? Thanks a lot, spk |
No matter which wall treatment is used or what the manual says, Yplus values of 300 are too high.
Even though the enhanced wall treatment should make the results independent of Yplus values in a certain range, it still works best for Yplus below 100. The use of wall functions assumes a certain profile of velocities and turbulence quantities. This profile is quite the same in most turbulent flows for Yplus below 100. Further away from the wall, the profiles is no longer universal. |
Hi spk,
with my experience, it's difficult to adapt y+ value to the range by remeshing. so you can solve it by using other type wall funciton equation and turbulent model, such as k-e turbulent model with scalable wall funciton, SST K-w turbulent model with standard wall function. Hope that helps |
For k-e model and enhanced wall function u need to have y+ below 10 near wall and rest of the mesh can have higher y+ it dont matter.
For that try to have minimum possible mesh spacing near the wall. It will help. |
can someone please explain me what is exact definition of wall function and how it is applied in cfd
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Hi anvesh,
Try this link for some basics. http://www.computationalfluiddynamic...oundary-layer/ You can get more details in ANSYS CFD Turbulence modelling presentation if you have customer credentials. Hope this helps |
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I have a equation: Is there SST K-w turbulent model with standard wall function in Fluent? I think that such a option is not in Fluent. I am grateful that someone show me this option in fluent. Thanks, Best Amir |
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Do you explain more about scalable wall function? Where do this option in Fluent? Thanks, Best. Amir |
Hi everybody,
I am grateful that someone explain me about following question and If someone can, please place useful links about this equation. What difference is between following options in Fluent? -standard wall functions -non-equilibrium wall functions -Enhanced wall treatment -User-defined wall functions Thanks, Best. Amir |
How do i change my y plus value it is currently above 1000 the fluent documentation says 300 is the maximum limit for k epsilon models how do i change this
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Hi Lucky Tran ,
Thanks for the prompt reply. I was trying to adapt the mesh in fluent selecting max and minm value of 30-300 as per the fluent k epslion documentation regarding y + value. However I am able to reduce my value but i dont get a contour maxima and minima between 30 to 300 any suggestions regarding this ? |
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