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y+ viscous sublayer query

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Old   April 5, 2021, 06:11
Default y+ viscous sublayer query
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Jowan S
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Dear CFD users

As part of my project, I am looking at the lift and drag coefficients for an aerofoil by doing 2D CFD simulations in Ansys Fluent.

I have been advised that my model should have a y+<11 to be in the viscous sublayer, however I was unable to get the y+ of my model less than 180.

Am I correct in thinking that this is also acceptable as this is outside the buffer zone and so is approximated sufficiently by the wall functions?

If so, what is the advantage of the y+ being in the viscous sublayer rather than in the turbulent zone?



I am quite new to CFD and a novice in terms of y+ but would like to touch on it briefly in my reports so would appreciate it if some one was kind enough to answer these questions.

Thanks a lot in advance!
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Old   April 5, 2021, 17:48
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Lorenzo Galieti
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It may work, sometimes the wall function is accurate, sometimes not, who knows... It is definitely better to solve the boundary layer rather than calculating it with a wall function, especially for airfoils. So yes, aim for y+ = 1, follow what your supervisor told you
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Old   April 5, 2021, 18:38
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Lorenzo Galieti
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Double post error
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aerofoil, ansys fluent, ansys workbench, y plus ranges, y plus selection

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