rasidual in each cell, location of the cells with maximum residuals

flux · November 28, 2013, 09:48

Hi,

is there any posibility to show me the positions of the cells, which have the highest residuals?

I couldn't find something in the manual...

THX!

Alex C. · November 28, 2013, 10:23

One thing you can do, is create a user-defined field function which correspond to your model.

If you are using an incompressible, then
$\nabla$ $\vec{V}$ = 0

Therefore, if you create a field function which is div(V), it should show values near 0 in each cell.

The value I suggest you display will not be the same as residuals, but at least it can show you what part of the domain is less precise.

You can also create field-function for momentum equations, and eventually energy and turbulence, if you want to.

azt · November 28, 2013, 11:48

Hi

There is an easier way.

If you're using the segregated solver then:

solver -> segregated flow-> check the temporary storage retained box in the expert properties window

and run for 1 iteration.

The momentum residuals will be written out to field functions.

azt

flux · November 29, 2013, 05:53

ok thx...

now i've got field functions with the residuals... but how can i see the distribution over the cells... a scalar scene didn't show anything...

azt · November 29, 2013, 08:57

Hi
you should be able to plot these as a scalar field.

you can createa report that gives you the max and min values. You can then create a threshold with say the top 10% and bottom 10% value and plot this.

That's how you do it.

azt

flux · November 29, 2013, 10:18

hm... i don't get any scalar-field plots.

i created a new scalar scene. Under displayers/Scalar 1, I added (under Parts) my fluid region. Under scalar field, i choose a Residual-field-function and nothing is happening.

It seems that this values are empty... because it does not show any Min/Max Values.

edit:

i forgot to say, that i am using a cluster... so on my desktop-pc, the values are available... is there any way to save the field functions in the .sim file?

there is another question: some residuals are negative... is there a way to get the values of residuals, which are displayed in the residual-plot?

azt · November 30, 2013, 05:17

hi

you can't save temporary storage stuff to the sim file, which is a real pain. However you can write out the scaler field to a table file, and read it in later on.

azt

flux · December 2, 2013, 06:33

hi, thx! can you give me a short instruction, how to write out a scalar field to a table file?

azt · December 3, 2013, 07:26

hi
tools -> tables -> right click -> new table -> xyz internal table

chose parts and scalars you want to export

then right click -> extract then right click export

Read this file in later and create a field function using the function InterpolatePositionTable

see help for syntax

azt

flux · December 10, 2013, 09:48

sorry for my late answer! i will try it, thx!

Walther · August 24, 2016, 19:17

Sry for this post. After I read azt´s answer I thought this option for temporary storage retained is only available for segregated and posted my question. But you can use it for coupled or turbulence solvers, too. I wanted to delete my post, but couldnt find a way to do it.

November 28, 2013, 09:48	rasidual in each cell, location of the cells with maximum residuals	#1
flux New Member Join Date: Oct 2013 Posts: 21 Rep Power: 13	Hi, is there any posibility to show me the positions of the cells, which have the highest residuals? I couldn't find something in the manual... THX!

November 28, 2013, 10:23		#2
Alex C. Member Join Date: Jul 2013 Posts: 56 Rep Power: 13	One thing you can do, is create a user-defined field function which correspond to your model. If you are using an incompressible, then $\nabla$ $\vec{V}$ = 0 Therefore, if you create a field function which is div(V), it should show values near 0 in each cell. The value I suggest you display will not be the same as residuals, but at least it can show you what part of the domain is less precise. You can also create field-function for momentum equations, and eventually energy and turbulence, if you want to. ebringley likes this.

November 28, 2013, 11:48	residuals	#3
azt Member allan thomson Join Date: Mar 2009 Location: scotland Posts: 45 Rep Power: 17	Hi There is an easier way. If you're using the segregated solver then: solver -> segregated flow-> check the temporary storage retained box in the expert properties window and run for 1 iteration. The momentum residuals will be written out to field functions. azt crevoise, Alex C., piousdookie and 2 others like this.

November 29, 2013, 08:57	stuff	#5
azt Member allan thomson Join Date: Mar 2009 Location: scotland Posts: 45 Rep Power: 17	Hi you should be able to plot these as a scalar field. you can createa report that gives you the max and min values. You can then create a threshold with say the top 10% and bottom 10% value and plot this. That's how you do it. azt

November 30, 2013, 05:17	stuf	#7
azt Member allan thomson Join Date: Mar 2009 Location: scotland Posts: 45 Rep Power: 17	hi you can't save temporary storage stuff to the sim file, which is a real pain. However you can write out the scaler field to a table file, and read it in later on. azt

November 29, 2013, 05:53		#4
flux New Member Join Date: Oct 2013 Posts: 21 Rep Power: 13	ok thx... now i've got field functions with the residuals... but how can i see the distribution over the cells... a scalar scene didn't show anything...

November 29, 2013, 10:18		#6
flux New Member Join Date: Oct 2013 Posts: 21 Rep Power: 13	hm... i don't get any scalar-field plots. i created a new scalar scene. Under displayers/Scalar 1, I added (under Parts) my fluid region. Under scalar field, i choose a Residual-field-function and nothing is happening. It seems that this values are empty... because it does not show any Min/Max Values. edit: i forgot to say, that i am using a cluster... so on my desktop-pc, the values are available... is there any way to save the field functions in the .sim file? there is another question: some residuals are negative... is there a way to get the values of residuals, which are displayed in the residual-plot?

December 2, 2013, 06:33		#8
flux New Member Join Date: Oct 2013 Posts: 21 Rep Power: 13	hi, thx! can you give me a short instruction, how to write out a scalar field to a table file?

December 3, 2013, 07:26		#9
azt Member allan thomson Join Date: Mar 2009 Location: scotland Posts: 45 Rep Power: 17	hi tools -> tables -> right click -> new table -> xyz internal table chose parts and scalars you want to export then right click -> extract then right click export Read this file in later and create a field function using the function InterpolatePositionTable see help for syntax azt

December 10, 2013, 09:48		#10
flux New Member Join Date: Oct 2013 Posts: 21 Rep Power: 13	sorry for my late answer! i will try it, thx!

August 24, 2016, 19:17		#11
Walther New Member Join Date: Aug 2016 Posts: 5 Rep Power: 10	Sry for this post. After I read azt´s answer I thought this option for temporary storage retained is only available for segregated and posted my question. But you can use it for coupled or turbulence solvers, too. I wanted to delete my post, but couldnt find a way to do it. Matthew Huang likes this.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[snappyHexMesh] Snappy creates strange cells far away from boundary	vainilreb	OpenFOAM Meshing & Mesh Conversion	3	December 16, 2020 06:11
Solution Diverging with Trimmer Mesh	rietuk	STAR-CCM+	8	February 27, 2013 05:50
[Other] cgnsToFoam problems with "QUAD_4" cells	lentschi	OpenFOAM Meshing & Mesh Conversion	1	March 9, 2011 05:49
Errors running allwmake in OpenFOAM141dev with WM_COMPILE_OPTION%3ddebug	unoder	OpenFOAM Installation	11	January 30, 2008 21:30
Ghost cell location for inclined cavity flow	zonexo	Main CFD Forum	13	September 9, 2005 03:00