Spacing value in ICEM CFD

avi031 · September 22, 2011, 04:04

Hello all,

I want to know what is meant by "Spacing" in Edge parameters box in ICEM CFD. I know it is for biasing the mesh. Is there a way to correlate the value for 'spacing' in ICEM CFD with Y+ value?
If Y+ value should be less than 1, then what would be the appropriate value for 'Spacing'? Please let me know...

Regards
Avinash

BrolY · September 22, 2011, 06:07

For a geometric 1 law, if you specify a spacing of 1, the length between the two first nodes would be of 1. After, it depends on the ratio.

The Y+ is not the spacing. The Y+ depends on your turbulence model. The spacing will be the value of the height of your first boundary layer.

About the height of your first boundary layer, you have to calculate it by yourself. Most of the solvers give you the formula which is used by the code. It depends on your turbulence model, velocity, geometry and fluid specifications.

avi031 · September 22, 2011, 07:02

BrolY,

Thank you for the reply.......Do you mean to say that the Y+ value will vary with turbulence model????

BrolY · September 22, 2011, 08:01

What I mean is the Y+ range depends on the turbulecne model. For example :
For a Rij-Epsilon model, a Y+ between 30 and 200 is recommanded.
For a k-omega model, a Y+ between 1 and 10 is recommanded.

plabon0709 · July 21, 2013, 01:13

Quote:

Originally Posted by BrolY

What I mean is the Y+ range depends on the turbulecne model. For example :
For a Rij-Epsilon model, a Y+ between 30 and 200 is recommanded.
For a k-omega model, a Y+ between 1 and 10 is recommanded.

Then what do is the meaning of y+ value 1....all the expert says y + value 1 is batter.then why it will be 30 to 300

PSYMN · July 22, 2013, 14:47

We would like to use an infinite number of elements and solve it in no time... But instead we make compromises. A Y+ of 1 would be great if you have the time and resources, but solvers put a lot of emphasis on doing more with less.

September 22, 2011, 04:04	Spacing value in ICEM CFD	#1
avi031 New Member Avinash Join Date: Jan 2011 Posts: 18 Rep Power: 15	Hello all, I want to know what is meant by "Spacing" in Edge parameters box in ICEM CFD. I know it is for biasing the mesh. Is there a way to correlate the value for 'spacing' in ICEM CFD with Y+ value? If Y+ value should be less than 1, then what would be the appropriate value for 'Spacing'? Please let me know... Regards Avinash

September 22, 2011, 06:07		#2
BrolY Senior Member AB Join Date: Sep 2009 Location: France Posts: 323 Rep Power: 22	For a geometric 1 law, if you specify a spacing of 1, the length between the two first nodes would be of 1. After, it depends on the ratio. The Y+ is not the spacing. The Y+ depends on your turbulence model. The spacing will be the value of the height of your first boundary layer. About the height of your first boundary layer, you have to calculate it by yourself. Most of the solvers give you the formula which is used by the code. It depends on your turbulence model, velocity, geometry and fluid specifications. soheil_r7 likes this.

July 22, 2013, 14:47		#6
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	We would like to use an infinite number of elements and solve it in no time... But instead we make compromises. A Y+ of 1 would be great if you have the time and resources, but solvers put a lot of emphasis on doing more with less. BrolY likes this. __________________ ----------------------------------------- Please help guide development at ANSYS by filling in these surveys Public ANSYS ICEM CFD Users Survey This second one is more general (Gambit, TGrid and ANSYS Meshing users welcome)... CFD Online Users Survey

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September 22, 2011, 07:02		#3
avi031 New Member Avinash Join Date: Jan 2011 Posts: 18 Rep Power: 15	BrolY, Thank you for the reply.......Do you mean to say that the Y+ value will vary with turbulence model????

September 22, 2011, 08:01		#4
BrolY Senior Member AB Join Date: Sep 2009 Location: France Posts: 323 Rep Power: 22	What I mean is the Y+ range depends on the turbulecne model. For example : For a Rij-Epsilon model, a Y+ between 30 and 200 is recommanded. For a k-omega model, a Y+ between 1 and 10 is recommanded.