mutUwallFunction and mutkWallFunction
 

has had anyone any experience with various types of mut wall functions?
whats their differences?
thank for any advice.

mutUwallFunction computes mut based on "U"

mutkWallFunction computes mut based on "k"

To me, mutkWallFunction has to be used where your mesh is coarse and the velocity gradient is "simulated" by the wall function. While the mutUwallFunction has to be used where your mesh is coarse and the velocity gradient in the boundary layer is "known".

thank you dear Heckman
I think you mean fine mesh about mutUWallFunction.
are you pointing to the extreme limits of low-Re and high-Re meshes and mutkWallFunction should be used in high-Re and mutUWallFunction in low-Re only or your intention is to speak about coarse or fine generally(not a certain criteria)?
and whats your opinion about using RANS methods in transient cases?because I have heard its not suitable for unsteady simulations?till what extent it may be true?
thanks.