spatial resolution in StarCCM+ for LES

aqua · March 10, 2014, 09:37

Dear All, I am performing LES in StarCCM+. To make sure the mesh is reasonable, I need to check the spatial resolution including Y+, as well as X+ and Z+ in the other two directions. StarCCM+ already has the field function of Y+, but how to get the spacitial resolution for the other direction, X+ and Z+?

Thank you so so much !

Aqua

me3840 · March 10, 2014, 11:20

Y+ does not refer to a specific direction, it is a parameter which is relative to the local face normal. X+ and Z+ do not exist.

Please read up here:
http://en.wikipedia.org/wiki/Law_of_the_wall

flotus1 · March 10, 2014, 12:03

and

do exist.
You can estimate them through the extent of the cell in the respective direction.
Say you have a certain value of

for a cell which has an extent of $\Delta y$ in y-direction.
Then the value for

is
$x^+ = y^+ \frac{\Delta x}{\Delta y}$ .
Same with

.

Pay attention that this concept is only valid for the first cell near a wall where

is related to the wall-normal extent of the cell.

me3840 · March 10, 2014, 12:20

I meant they don't exist in STAR-CCM+, sorry.

I don't see any method of calculating these values without user code, unless the geometry is simple enough to know the cell dimensions a priori.

aqua · March 11, 2014, 06:52

Hi, thank you very much for your reply... which really shocked me... StarCCM+ does not have x+ and z+ ? OMG... If that's true, I would have big trouble with my work..

Thank you.
Aqua

Quote:

Originally Posted by me3840

I meant they don't exist in STAR-CCM+, sorry.

I don't see any method of calculating these values without user code, unless the geometry is simple enough to know the cell dimensions a priori.

aqua · March 11, 2014, 06:57

Hello Alex, thank you for your kind reply. I understand your explanation, but my problem is , how to get it from StarCCM+... do you have any idea?

In Starccm+, I can get Y+, but then , to calculate X+ and Z+, I would need the size of the cell (width or length), which is an issue for me...

Thank you

Aqua

Quote:

Originally Posted by flotus1

and

do exist.
You can estimate them through the extent of the cell in the respective direction.
Say you have a certain value of

for a cell which has an extent of $\Delta y$ in y-direction.
Then the value for

is
$x^+ = y^+ \frac{\Delta x}{\Delta y}$ .
Same with

.

Pay attention that this concept is only valid for the first cell near a wall where

is related to the wall-normal extent of the cell.

flotus1 · March 11, 2014, 10:29

No need to be shocked, no general purpose commercial CFD software has predefined functions for these values.
As pointed out by me3840, you will need some user code to get them unless you have a very simple setup.
I am no longer working with CCM+, so I cant really give you a hint how to do this.

March 10, 2014, 09:37	spatial resolution in StarCCM+ for LES	#1
aqua Member Aqua Join Date: Oct 2011 Posts: 96 Rep Power: 14	Dear All, I am performing LES in StarCCM+. To make sure the mesh is reasonable, I need to check the spatial resolution including Y+, as well as X+ and Z+ in the other two directions. StarCCM+ already has the field function of Y+, but how to get the spacitial resolution for the other direction, X+ and Z+? Thank you so so much ! Aqua

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
High resolution image with parafoam	Andrea_85	OpenFOAM	5	January 23, 2014 06:39
Mesh Resolution to resolve turbulent boundary layer	tongx051	FLUENT	1	October 22, 2013 00:18
importing cad geometry, starCCM 64bit??	syd	STAR-CCM+	3	March 30, 2010 07:17
[Other] Problems with starccm mesh	AndTen	OpenFOAM Meshing & Mesh Conversion	1	February 23, 2010 04:43
Large difference in grid resolution for diff paper	Ben	Main CFD Forum	16	April 7, 2007 11:45

March 10, 2014, 11:20		#2
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	Y+ does not refer to a specific direction, it is a parameter which is relative to the local face normal. X+ and Z+ do not exist. Please read up here: http://en.wikipedia.org/wiki/Law_of_the_wall

March 10, 2014, 12:03		#3
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,398 Rep Power: 46	and do exist. You can estimate them through the extent of the cell in the respective direction. Say you have a certain value of for a cell which has an extent of $\Delta y$ in y-direction. Then the value for is $x^+ = y^+ \frac{\Delta x}{\Delta y}$ . Same with . Pay attention that this concept is only valid for the first cell near a wall where is related to the wall-normal extent of the cell.

March 10, 2014, 12:20		#4
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	I meant they don't exist in STAR-CCM+, sorry. I don't see any method of calculating these values without user code, unless the geometry is simple enough to know the cell dimensions a priori.

March 11, 2014, 10:29		#7
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,398 Rep Power: 46	No need to be shocked, no general purpose commercial CFD software has predefined functions for these values. As pointed out by me3840, you will need some user code to get them unless you have a very simple setup. I am no longer working with CCM+, so I cant really give you a hint how to do this.