Going over δ99?

Is it ok if you go a bit under or a lot over δ99? I have been trying to perfect my y+ under 1(because I tried for 2 days straight to get 30 < y+ < 300 and never got it) and I finally achieved it and got very good residuals but my δ99 was off by a bit because it was too small, should I increase the size to over δ99?

thank you for the help,
Frank Lucci

Hello frank can you please share the project link with us so that we can have a look at the residuals ourselves?

Best regards Sebastian

@SBlock MediWing, 0 aoa, full scale(final), Simulation
accurately y+ under 1(fingers crossed), the y+ is under 1 but there is this giant weird flow separation right here -

here is what I think its suppose to look like -

I don’t know what this is happening, perhaps you have an idea?
Frank Lucci

Hi Frank,

my guess would be that the k-w-SST solver, which we use, is mostly designed to solve all Y+. This can result in some inaccuracy for extreme Y+ areas and Y+ values for the buffer layer ( 3 < Y+ <30). Due to that fact, such inaccuracy can occur. That’s why you will always have to do the mesh sensitivity analysis and physical validation. In best cases you can do physicaltesting and apply this information on the selection of your turbulence model.

If the data you get to not have a big difference ( Drag/Lift Coeffiecent) I wouldn’t be too concerned. But for sure that would be an area of interest when doing physical testing.

Best regards Sebastian

hello, I reduced the inflation layers to ten so that the y+ would be 1 and it worked and it stabilized and the whole thing looks good, I think it was because there was a missing inflation layer when I did 15

frank lucci

Yes this can happen if the aspect ratio in the inflation layers gets too small. With that, a bigger layer would be needed.

But I guess you are good with the 10 layers.

Best regards Sebastian