Y+ value

April 29, 2005, 04:22

hello all,

My model has around 64000 cells. Fluent specifies that the Y+ values is Ok if less than 5 or more than 30. Can anyone suggest what is the optimum value of Y+ that I should get. I am using ske model.

Sham.

April 29, 2005, 06:21

30-60 for ske without enhanced wall treatment an Re > 8000 (5000)

April 29, 2005, 11:26

But i am using enhanced wall treatment with Re 1.4e5. I get values around more than 100. when I try to adapt boundary, the Y+ value does go down but the results isn't good. How can I overcome this. Tq.

Sham.

May 3, 2005, 02:44

100 should not be so bad, if you look for pressure losses in pipes e.g.. In cases of detached flow of course you need lower values for high accuracy results.

For the prediction of cL or cD values of airfoils e.g. (your high Re seems to indicate this) it seems to be necessary to refine your grid up to y+=1 and to have enough grid layers inside the boundary layer in order to get results of the accuracy you expect.

But I am not the expert for that field of investigation. Ask s.o. from aerodynamics.

April 29, 2005, 04:22	Y+ value	#1
Sham Guest Posts: n/a	hello all, My model has around 64000 cells. Fluent specifies that the Y+ values is Ok if less than 5 or more than 30. Can anyone suggest what is the optimum value of Y+ that I should get. I am using ske model. Sham.

April 29, 2005, 06:21	Re: Y+ value	#2
Volker Pawlik Guest Posts: n/a	30-60 for ske without enhanced wall treatment an Re > 8000 (5000)

April 29, 2005, 11:26	Re: Y+ value	#3
Sham Guest Posts: n/a	But i am using enhanced wall treatment with Re 1.4e5. I get values around more than 100. when I try to adapt boundary, the Y+ value does go down but the results isn't good. How can I overcome this. Tq. Sham.

May 3, 2005, 02:44	Re: Y+ value	#4
Volker Pawlik Guest Posts: n/a	100 should not be so bad, if you look for pressure losses in pipes e.g.. In cases of detached flow of course you need lower values for high accuracy results. For the prediction of cL or cD values of airfoils e.g. (your high Re seems to indicate this) it seems to be necessary to refine your grid up to y+=1 and to have enough grid layers inside the boundary layer in order to get results of the accuracy you expect. But I am not the expert for that field of investigation. Ask s.o. from aerodynamics.