# Define y+ in fluent

Hi every one

I want to plot Y+ vs U+ but the value of y+ is very small because I used y+=0.1 to 1 For LES model so how can I get a y+ values like 100 or 300

I read some of the discussions and some of them talk about define y+ how can I define it???

## Comments

Please post the questions in appropriate category. Moving this question to other category to get better response.

Moving to fluid dynamics.

You will need to coarsen the mesh to increase y+ value.

At the same time, for LES it is required to get Y+ as 1.

Regards,

Keyur

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thanks for the reply.

ok, I will move it. but I need to plot some quantities with y+ so I need to get y+ at least =20

You need to code the expression for Yplus so that you can plot along a line normal to the wall.

https://studentcommunity.ansys.com/thread/define-y-in-fluent-2/

Mr. rwoolhou I don't waste your time I try to put y+=1 but that not enough so I need the code to define y+ and I need more than one mesh, so I want to test the effect of y + on simulation

thank you for your advice

I try to do that yplus=(y*ut /kinematic viscosity) but her what y mean wall distance or coordinate y or what

thank you very much

plot y+ vs ut

that what I got it

Looks good or not? Just remember that Cell Wall Distance is the distance to the next wall.

the value of y+ is also small so not good I need a big value like 20 or 30

Then use a coarser mesh.

Mr.rwoolhou I know courser mesh gives a large value of y+ but I ask if I can get a large value of y+ from a fine mesh