SimScale CAE Forum

Yplus Range


#1

I have not had any luck being able to see the ACTUAL yPlus Range using the 1s simulation method. That is OK to view the layers that were created in the mesh but I do not believe that you will see any relevant yPlus values. At the 1s state there has been no convergence yet and although the yPlus does have a range at 1s, I see it is a quasi ‘normalized’ range with what appears to be an average of about 1.

ONLY when I did a simulation to convergence, did I see the real range that I am seeking which in my situation is suggested as a 30 to 300 range.

This recommendation caused me countless hours of hair pulling and many core hours down the drain. I know it only mentions being able to see yPlus but that implies to me that you are seeing a relevant range of yPlus values too.


Y+ (yplus) - Generate Wall Spacing for CFD
#2

Hi Dale!

I guess my colleague Darren (@1318980) is already working on a solution for this in this thread, isn’t he? \rightarrow XFLR5 vs CFD

If I am mistaken please tell me so that we can fix this asap!

Cheers,

Jousef


#3

I thought this was important enough to warn of a potential time wasting (confusing at the very least) recommendation, where I found the recommendation.

I hope many people work on this to confirm my finding and prove me wrong so I can apologize and erase my posts about it… but I what if I am correct? :upside_down_face:


#4

Hi @DaleKramer, to me, it makes sense that Y+ results at 1s would not be realistic. The reason being that Y+ at the first cell is calculated as a function of velocity, where if velocity is not converged then Y+ would also not be converged. I am not sure what Y+ initialises as but I would give a guess that if you’re seeing average values of 1 then it would initialise as that value.

Hope this sheds a little light on the matter,
Darren


#5

I understand that you would not look at a 1s simulation to check that your yPlus range is between 30 and 300.

But the recommendation was to do a 1s simulation so you could see your yPlus values. As a newbie, I did not realize that the 1s values actually have no meaning with reference to looking for a 30 to 300 range.

What are the 1s yPlus values good for?


#6

Sorry, where was this recommendation? Just so I can read it :slight_smile:


#7

Here, it is also where I posted the above message with the quote.


#9

Good job Dale!

I adapted the post and it makes no sense to check y+ if the velocities are not converged properly. Please let me know if you have any other wishes or feedback!

Jousef