Dear Sir,

I was really confused in CFX Yplus. I can check the value of Yplus in CFX-post, but which is good? Yplus>11 or Yplus<11 Thank you in advance.

Best Regards Eric

Refer to Guidelines for Mesh Generation in CFX Help. Basically, Yplus>20 (<200) for wall function. Yplus<2 for low-Re model.

BB

Hi,

Or use the automatic wall functions approach and let the solver take care of it, then you only have to worry about mesh independance.

Glenn Horrocks

Thank you very much for the kind reply

My simulation is compressible in a pipe. So, If 20 < Yplus <200, the resulte is acceptable. Is it right?

Thank you in advance.

Eric

It depends. You still need to validate & verify your solution. You should treat Y+ value as an indicator to minimise the numerical error, not to judge the accuracy of your solution.

Also you should ideally have 10 nodes or so in the BL.

Hi, Johnny. This is a general guideline only. You may need a lot more if boundary layer flow is important in your analysis.

Dear Friends,

Thank you for the reply and the discussion. If y+ plus is not good in my simulation, what can I do?

Many thanks

Eric

Make the innermost mesh layer thinner. Y+ is directly proportional to the cell height.

You have to limit the growth rate between adjacent layers as well.... I usually set it around 1.1~1.3

hi all,

This is naveen.i am working with the cfx 10,where i am analysing air flow past a circular cylinder.and my reynolds number is 7e+4.i would like to know for such kind of reynolds number ,which fluid flow ( transition flow or turbulence flow ) will influence more on my problem and why? how can i know exact critical reynolds number(transition point) for my case.

i want to hear from you,

thanks all

regards,

Naveen