[narayanan]

Hello,

I know this question has been asked and answered several times, but I did not see any conclusive remarks. I am performing a conjugate heat transfer analysis which is sensitive to heat transfer and pressure drop in the model.

In order to predict the heat transfer and the turbulence within the domain accurately, I would like to use either SST k-w or realizable k-e with Enhanced wall treatment turbulence models. From Fluent's Intro guide, I realize that both these models are y+ insensitive models and it would be best to have y+≈1.

But due to the model's complexity and computing restrictions I cannot get the first cell distance which would satisfy the wall y+≈1. My question is how does these models respond when the y+ is in the range of 10-20? I know that wall functions gets into effect if the first cell is in the log layer (y+≈30), but what happens when the first cell has y+ of approximately 10?

Thank you in advance for your answers.

[LuckyTran]

Originally Posted by narayanan

I know that wall functions gets into effect if the first cell is in the log layer (y+≈30)

No you don't actually. Because if you did you would know that.....

Originally Posted by narayanan

but what happens when the first cell has y+ of approximately 10?

Nothing happens because they are y+ insensitive (blended) wall functions. They don't have strict regimes because all the regimes are blended together.


What's much more important the the y+ of the wall adjacent cell is the number of cells you have across the boundary layer.