[ICEM] Exporting Grid Volumes/Areas from ICEM to Calculate Discretization Error

Josh · May 18, 2010, 15:12

Hi -

I'm trying to calculate the discretization error of my CFD simulations using Richardson's method as outlined in the Journal of Fluids Engineering:
http://journaltool.asme.org/Template...umAccuracy.pdf

I created my "2D" (one element deep) structured mesh using ICEM 12. If you observe Equation 2 (fourth page of the above link), you'll see that a representative cell size is required. Basically, I need the following parameters to solve the equation:

N = total number of cells
Ai = area of each cell (the i'th cell)
or...
Vi = volume of each cell

I know how to get N, but I don't know how to export a file from ICEM with the area (or volume) of each cell.

Is it possible to export a file from ICEM with the volume of each cell? If so, how?

Thanks for any help!

PSYMN · May 19, 2010, 13:05

There are diagnostics that create a historgram for a property such as volume, but I don't know how to do exactly what you want. I will look into it and get back to you...

Josh · May 19, 2010, 20:48

Thanks, as always, Simon.

PSYMN · May 20, 2010, 12:58

Not sure how comfortable you are with scripting, but I think it will be the only way to produce a file with this info for each element.

You will need to look into the programmers guide and tcl scripting in general, but I asked one of my friendly neighborhood developers (actually he is on a different continent) for some tips and he sent me this...

At least it looks easy for the surface elements.

Enjoy...

There exists 2 commands to get volume/area information.

set area [ic_uns_area $subset_name]
set vol [ic_uns_volume $subset_name]

What the user needs to do is to create a subset ($subset_name) for each element in the mesh and to write this information into a file.

The following existing ic_ command writes the area information (only for shell elements) into a file:

ic_uns_write_elem_list all ./my_file_name

Output format of the file is

"element number" "area" "element node numbers"

Hope that helps a little.
Jari

Josh · May 20, 2010, 14:40

Thanks, Simon. Chances are I'll never get around to doing this, but it's good to have this as a reference should I have the time to try it.

May 18, 2010, 15:12	Exporting Grid Volumes/Areas from ICEM to Calculate Discretization Error	#1
Josh Senior Member Joshua Counsil Join Date: Jul 2009 Location: Halifax, Nova Scotia, Canada Posts: 366 Rep Power: 18	Hi - I'm trying to calculate the discretization error of my CFD simulations using Richardson's method as outlined in the Journal of Fluids Engineering: http://journaltool.asme.org/Template...umAccuracy.pdf I created my "2D" (one element deep) structured mesh using ICEM 12. If you observe Equation 2 (fourth page of the above link), you'll see that a representative cell size is required. Basically, I need the following parameters to solve the equation: N = total number of cells Ai = area of each cell (the i'th cell) or... Vi = volume of each cell I know how to get N, but I don't know how to export a file from ICEM with the area (or volume) of each cell. Is it possible to export a file from ICEM with the volume of each cell? If so, how? Thanks for any help!

May 19, 2010, 13:05	Hmm...	#2
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	There are diagnostics that create a historgram for a property such as volume, but I don't know how to do exactly what you want. I will look into it and get back to you...

May 20, 2010, 12:58	Scripting...	#4
PSYMN Senior Member Simon Pereira Join Date: Mar 2009 Location: Ann Arbor, MI Posts: 2,663 Blog Entries: 1 Rep Power: 47	Not sure how comfortable you are with scripting, but I think it will be the only way to produce a file with this info for each element. You will need to look into the programmers guide and tcl scripting in general, but I asked one of my friendly neighborhood developers (actually he is on a different continent) for some tips and he sent me this... At least it looks easy for the surface elements. Enjoy... There exists 2 commands to get volume/area information. set area [ic_uns_area $subset_name] set vol [ic_uns_volume $subset_name] What the user needs to do is to create a subset ($subset_name) for each element in the mesh and to write this information into a file. The following existing ic_ command writes the area information (only for shell elements) into a file: ic_uns_write_elem_list all ./my_file_name Output format of the file is "element number" "area" "element node numbers" Hope that helps a little. Jari

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May 19, 2010, 20:48		#3
Josh Senior Member Joshua Counsil Join Date: Jul 2009 Location: Halifax, Nova Scotia, Canada Posts: 366 Rep Power: 18	Thanks, as always, Simon.

May 20, 2010, 14:40		#5
Josh Senior Member Joshua Counsil Join Date: Jul 2009 Location: Halifax, Nova Scotia, Canada Posts: 366 Rep Power: 18	Thanks, Simon. Chances are I'll never get around to doing this, but it's good to have this as a reference should I have the time to try it.