Regarding Y+

muthuvelcfd · November 18, 2009, 04:16

hi friend i have one doubt where i have to give the value of y + in starccm during simulation

aerospaceman · November 18, 2009, 19:28

Hey there,

As I understand it, you control your Y+ by the prism layer meshing settings.

There you can specify 1st wall thickness, total boundary layer thickness, number of cells etc.

These, as you know from your aerodynamics theory,then control your Y+.

If you want a more detailed explanation, let me know and I can supply you with the equations or links to them.

Hope this helps.

madcfd · December 9, 2009, 08:04

hi aerospaceman,

I am wondering how to figure out the boundary layer thickness for a nozzle flow.
Could you give me a detailed explanations, if possible with equations.

nvtrieu · January 3, 2010, 00:36

Quote:

Originally Posted by aerospaceman

Hey there,

As I understand it, you control your Y+ by the prism layer meshing settings.

There you can specify 1st wall thickness, total boundary layer thickness, number of cells etc.

These, as you know from your aerodynamics theory,then control your Y+.

If you want a more detailed explanation, let me know and I can supply you with the equations or links to them.

Hope this helps.

Hello Aerospaceman,

I've been working with Star-CCM+ V3.06. I would like to know how to estimate the y+, as you said by using "prism layer mesher" right? so could you tell me more clearly?
thanks in advance!

email: trieuckgt@gmail.com
MSN: trieu.dut@livemail.com
YM: trieu_tme@yahoo.com

abdul099 · January 7, 2010, 08:24

Hi

i'm not sure, if i've understood your problem the right way.
A good estimation for the near wall prism layer of a flat plate could be found by using the tool on http://geolab.larc.nasa.gov/APPS/YPlus/ .
I'm doing simulation on an airfoil, so i specify the near wall prism layer thickness, using the value calculated by this tool, and it works very well.

After the simulation, you should do a scalar plot of the y+ value and adjust the near wall prism layer thickness if the y+ does not meet the requirements.

greetings

asherah · February 21, 2010, 14:41

Quote:

Originally Posted by abdul099

Hi

i'm not sure, if i've understood your problem the right way.
A good estimation for the near wall prism layer of a flat plate could be found by using the tool on http://geolab.larc.nasa.gov/APPS/YPlus/ .
I'm doing simulation on an airfoil, so i specify the near wall prism layer thickness, using the value calculated by this tool, and it works very well.

After the simulation, you should do a scalar plot of the y+ value and adjust the near wall prism layer thickness if the y+ does not meet the requirements.

greetings

Hiya thank you for sharing that calculator, in that calculator, there is a refrence length, and output, what are they?

Many thanks

Asherah

Maddin · February 22, 2010, 02:02

The output is the thickness of the first layer. For CCM you must calc it with the stretching factor and the numbers of layer.

Knigge46 · February 13, 2015, 04:53

Hi Folks,
I don't know if you noticed, but CFD-Online has it's own Y+-Calculator!
It's very handy and gives you the near wall thickness as an ouput for your desired Y+-value.
It also gives a link to the wiki, where the formulas are explained in detail.

November 18, 2009, 04:16	Regarding Y+	#1
muthuvelcfd New Member stephenraj Join Date: Oct 2009 Posts: 7 Rep Power: 16	hi friend i have one doubt where i have to give the value of y + in starccm during simulation

November 18, 2009, 19:28		#2
aerospaceman Member Join Date: Nov 2009 Posts: 43 Rep Power: 16	Hey there, As I understand it, you control your Y+ by the prism layer meshing settings. There you can specify 1st wall thickness, total boundary layer thickness, number of cells etc. These, as you know from your aerodynamics theory,then control your Y+. If you want a more detailed explanation, let me know and I can supply you with the equations or links to them. Hope this helps. Last edited by aerospaceman; November 24, 2009 at 10:53.

February 13, 2015, 04:53	Y+ Calculator	#8
Knigge46 New Member Jan N. Wieczorek Join Date: Jul 2014 Posts: 14 Rep Power: 11	Hi Folks, I don't know if you noticed, but CFD-Online has it's own Y+-Calculator! It's very handy and gives you the near wall thickness as an ouput for your desired Y+-value. It also gives a link to the wiki, where the formulas are explained in detail. daenerys likes this.

December 9, 2009, 08:04		#3
madcfd New Member madhu Join Date: May 2009 Posts: 4 Rep Power: 16	hi aerospaceman, I am wondering how to figure out the boundary layer thickness for a nozzle flow. Could you give me a detailed explanations, if possible with equations.

January 7, 2010, 08:24		#5
abdul099 Senior Member Join Date: Oct 2009 Location: Germany Posts: 636 Rep Power: 21	Hi i'm not sure, if i've understood your problem the right way. A good estimation for the near wall prism layer of a flat plate could be found by using the tool on http://geolab.larc.nasa.gov/APPS/YPlus/ . I'm doing simulation on an airfoil, so i specify the near wall prism layer thickness, using the value calculated by this tool, and it works very well. After the simulation, you should do a scalar plot of the y+ value and adjust the near wall prism layer thickness if the y+ does not meet the requirements. greetings

February 22, 2010, 02:02		#7
Maddin Senior Member Join Date: Mar 2009 Posts: 260 Rep Power: 18	The output is the thickness of the first layer. For CCM you must calc it with the stretching factor and the numbers of layer.