Learning Forum

[Mitchell Durbin]

Hello,

I am doing a project related to turbulent flow boundary layers. I am attempting to calculate u+ so that I can make a plot of u+ vs. log(y+) along a line normal to a nozzle wall.

I have defined u+ in the following way:

However, a contour plot of u+ in my domain shows that u+ is zero everywhere.

I suspected that perhaps either the velocity magnitude, wall shear stress, or density are also zero everywhere, but that is not the case:

Interestingly, the following custom field functions also resulted in a contour of zero everywhere:

And, the following custom field function resulted in nan everywhere.

Clearly there is something going wrong in the custom field functions when "wall-shear" is involved. However, as mentioned above, the wall shear stress itself is NOT zero anywhere.

How can correctly define u+ to avoid this issue?

[Rob]

Wall shear is technically zero on your contour as it's calculated on the wall. You're displaying on the fluid domain. 

[SRP]

Hi,

Try to create custom function for u_tau then u/u_tau.

Thanks