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Old   February 18, 2006, 15:17
Default Yplus adaptation
  #1
danny
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Hi,

performing the Yplus adaptation on a wall, and using a standard k-epsilon turbulence model, what should be the value of the Min and Max Allowed in the Yplus/Ystar adaptation window? Thanks
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Old   February 19, 2006, 19:03
Default Re: Yplus adaptation
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MOHAMMED TOLBA
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from FLUENT 6.1 Documentation:

Near-Wall Mesh Guidelines for Wall Functions :

A value close to the lower bound (yplus ~=30 ) is most desirable.

Although FLUENT employs the linear (laminar) law when , using an excessively fine mesh near the walls should be avoided, because the wall functions cease to be valid in the viscous sublayer.

It is important to have at least a few cells inside the boundary layer

Near-Wall Mesh Guidelines for the Enhanced Wall Treatment:

When the enhanced wall treatment is employed with the intention of resolving the laminar sublayer,yplus at the wall-adjacent cell should be on the order of yplus=1. However, a higher y+ is acceptable as long as it is well inside the viscous sublayer ( yplus<4 to 5).

You should have at least 10 cells within the viscosity-affected near-wall region (Rey<200 ) to be able to resolve the mean velocity and turbulent quantities in that region.

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Old   February 20, 2006, 12:41
Default Re: Yplus adaptation
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Riaan
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Set it to 30<y+<300.

This is a pretty good range for Wall-functions in general
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