[sandpants]

I am having extreme difficulty getting this to work. Likely because I have no clue what I am doing.

2D problem.

I am required to compare the law-of-the wall profile to the Uplus v Yplus computed in fluent for a K-Epsilon turbulent flow, kinda like whats shown here http://www.cfd-online.com/Forums/flu...-vs-yplus.html.

Fluent gives Yplus but not Uplus.

I tried defining Uplus as a Custom Field Function. Cannot get it to work - the contour plot gives zero (0) through out the whole fluid domain.
I am expressing Uplus as |V|/Utau, where Utau=sqrt(x-wall-shear/density).

The unnerving part is that Utau is not 0 near the wall(expected) and some distance from it and Velocity is only 0 at the wall (no slip). So why am I getting 0 EVERYWHERE through-out the fluid domain?

I am also having excessively large Yplus values reaching 700. I cannot refer to the source thread, but on these forums I've read that that would be due to high TKE. I have flow an inlet flow velocity of 30m/s and a hydraulic diameter of 0.177m. Re=354000. In the K-E setup I set TKE as 1.42m^2/s^2, but contour plots show TKE upto 40 in some places.

Please advise.

[LuckyTran]

The yplus value that Fluent gives you is only the yplus of the wall adjacent cell, also sometimes called wall y+. Fluent does not give you y+for any of the interior cells that are not directly adjacent to walls.

Try not to confuse this wall y+ with the canonical y+, which is closely related to the cell Reynolds number.

utau is a surface property whereas u+ and y+ are fields. My guess is you are trying dividing u(x,y,z) by utau which is defined only on the surface. Since utau is not defined on the interior, it it should not report any values there.

Garbage in, Garbage out.

[medguedem]

good hi
I have same problem how can i draw fluent u+ vs Y+ graph in cfd-post fluent
if you found a solution please send me.