Y+
 

Hi, I'm working with CFD for computing pressure drop in hydraulic valves. I don't really check my y+ values as I solve problems, because predictions are in good agreement. But since weeks, I try to understand a difference between pressure drop computed by Fluent with the one computed with simple formula. As I checked my y+, I saw that they were less than 30 while using k-epsilon model with standard wall functions. The only way to reach the 30 y+-value should to generate a coarser mesh. But according that I am in millimeter domain, and I have to solve tiny opening, I can't generate coarser mesh, else I would have gap with just 1 cell in the section. So normally, I should refine and enable the enhanced wall treatment options of the k-epsilon model. But that means, I am condemned to work only with enhanced option. Does anybody have the same problem or is there anybody who is working in hydraulics with components in millimeter-domain. Thanks Maxime

Re: Y+
 

For accurate pressure calculations near walls you will need very fine mesh, if you can make mesh of yplus near 1 its great. Enhanced wall functions are really a good idea, why do you think it will not give good results.

Re: Y+
 

Hi, I didn t say it won't give good results, I just said that in this optic I will never use Standard wall Fonctions, because my geometries and flow conditions conduct me to use Enhanced Wall treatment with very fine mesh. Maxime

Re: Y+
 

humm, now i got what you meant, but sadly i can not suggest anything for that. best of luck.