# Define y+ in fluent

• 53 Views
• Last Post 2 weeks ago
mutlaq404 posted this 3 weeks ago

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???

kkanade posted this 3 weeks ago

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

If this helps, please mark this post as 'Is Solution' to help others.

Guidelines on the Student Community

How to access ANSYS help links

mutlaq404 posted this 3 weeks ago

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

abenhadj posted this 3 weeks ago

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

Best regards, Amine

mutlaq404 posted this 3 weeks ago

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

I know that but I don't have any idea about the code and how can i write it, because I'm a beginner user

the wall yplus read only first layer so If you have any information that can help me, I will be grateful

rwoolhou posted this 3 weeks ago
mutlaq404 posted this 3 weeks ago

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

mutlaq404 posted this 3 weeks ago

I read discussions about finding y+ and Mr. abenhad talk about define y+ from a code because the wall y+ in the fluent don't give enough value of y+

abenhadj posted this 3 weeks ago

You define a custom field function with the expression of yplus from manual which you later can plot along any line.

Best regards, Amine

• Liked by
mutlaq404 posted this 3 weeks ago

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

abenhadj posted this 3 weeks ago

Wall distance

Best regards, Amine

mutlaq404 posted this 3 weeks ago

thank you very much

mutlaq404 posted this 3 weeks ago

plot y+ vs ut

that what I got it

abenhadj posted this 3 weeks ago

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

Best regards, Amine

• Liked by
mutlaq404 posted this 2 weeks ago

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

rwoolhou posted this 2 weeks ago

Then use a coarser mesh.

mutlaq404 posted this 2 weeks ago

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