Yplus checking
 

Hi

Ive been running a simulation with K epsilon turbulence model and hence in cfx mesh have been defining an first layer thickness for inflation layer with a Yplus of 20 as it says in cfx help. When i plot a graph in post processing of Yplus vs x distance around the inflation layer (its a flat plate) most of the graph is above 20 on the upper surface but at the tip and tail the vlaue goes as low as 2. Id say about 85 % was above 15.

How can i change this or this acceptable? Im using 10 layers of inflation but due to aspect ratios and setting the internal angle to 15deg there is only 3-4 layers at the tips/tail

Thnaks

Steven

Re: Yplus checking
 

Hi,

If you use the SST turbulence model then you can use automatic wall functions and therefore the range of y+ would be fine. Whether the y+ range you have with a k-eps model is a problem depends on the simulation. You will need to do a validation study to find out.

Glenn Horrocks

Re: Yplus checking
 

Also, your y+ value is heavily dependent upon your local Reynolds number, so in areas with stagnated flow such as the leading edge, your y+ will automatically decrease

Adam