CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Post-Processing

Modified volFieldValue

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree2Likes
  • 1 Post By olesen
  • 1 Post By olesen

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 1, 2020, 07:55
Default Modified volFieldValue
  #1
New Member
 
Giovanni Farina
Join Date: Nov 2019
Posts: 2
Rep Power: 0
the_ichthyologist is on a distinguished road
Hi all,
I'm new to OpenFOAM and have very limited knowledge of C++, I'm trying to modify the volFieldValue postProcess function in order to calculate 'weighted' percentiles (weighted with alpha.water - I'm using a modified interFoam - and cells volume). I'm using openfoam6.



I think I managed to compile a modified version of volFieldValue called "myvolFieldValue" without changing anything but adding a new operation (which doesn't do anything).


Now I'm trying to implement my function: basically I want to sort "values" of concentration field in a certain region of my mesh from lowest to highest, at the same time sort corresponding cell volumes and alphas with the same order; then sum over indices (dividing by the total \sum_{i=0}^ {N} V_{i} c_{i} \alpha{i} ) until I tick the various percentiles (0.05 , 0.15 etc.).


I modified a quicksort algorithm in c++ but I can't define the right variable type for the arrays. It would be useful to reshape the arrays to simple vectors, I don't know if this is already done by volFieldValue when 'values', 'weightField' and 'V' are passed.


I attach all relevant files, this is the main error (for now):


fieldValues/myvolFieldValue/myvolFieldValueTemplates.C:230:14: error: cannot convert ‘const Foam::Field<double>’ to ‘const Foam::Field<double>*’ for argument ‘1’ to ‘void quickSort(const Foam::Field<double>*, const Foam::Field<double>*, const Foam::Field<double>*, int, int)’
quickSort(values, weightField, V, 0, n-1);



I also don't know if quicksort function definition is at the right place in the code and if I loop correctly over the fields once they are sorted.



I apologise for my poor knowledge, any help would be much appreciated


Giovanni
Attached Files
File Type: txt compilationerror.txt (17.8 KB, 0 views)
File Type: c myvolFieldValueTemplates.C (8.5 KB, 0 views)
File Type: h myvolFieldValue.H (7.2 KB, 0 views)
File Type: c myvolFieldValue.C (5.0 KB, 0 views)
the_ichthyologist is offline   Reply With Quote

Old   September 11, 2020, 10:56
Default
  #2
Senior Member
 
Mark Olesen
Join Date: Mar 2009
Location: http://olesenm.github.io/
Posts: 1,001
Rep Power: 27
olesen will become famous soon enougholesen will become famous soon enough
Quote:
Originally Posted by the_ichthyologist View Post
Hi all,
...
Now I'm trying to implement my function: basically I want to sort "values" of concentration field in a certain region of my mesh from lowest to highest, at the same time sort corresponding cell volumes and alphas with the same order; then sum over indices (dividing by the total \sum_{i=0}^ {N} V_{i} c_{i} \alpha{i} ) until I tick the various percentiles (0.05 , 0.15 etc.).

I modified a quicksort algorithm in c++ but I can't define the right variable type for the arrays. It would be useful to reshape the arrays to simple vectors, I don't know if this is already done by volFieldValue when 'values', 'weightField' and 'V' are passed.
Instead of implementing/reimplementing quick sort, it makes more sense to leverage existing code. You could use the sortedOrder method directly, or with a hand-rolled comparator
https://develop.openfoam.com/Develop...ListOps.H#L190
When doing your sorted order, you use the 'primitiveField()' method on your volume field to obtain the underlying plain 'Field' (no dimensions, no boundaries). With this sorted order (the cell Ids in the sorted order), you can then walk through your other fields. I guess you will have to do all of the binning on each local process and then sum/merge the results across all processors.

the_ichthyologist likes this.
olesen is offline   Reply With Quote

Old   October 2, 2020, 05:56
Smile
  #3
New Member
 
Giovanni Farina
Join Date: Nov 2019
Posts: 2
Rep Power: 0
the_ichthyologist is on a distinguished road
Dear Mark,
Thank you very much! That's been very helpful!

I managed to make it work with this code

Quote:
scalarField vals(values.component(0));
scalarField myalpha(weightField.component(0)); // not used actually
scalarField myvol(V.component(0)); // not used actually

const double allconc=gSum(vals*weightField*V);

labelList order;
sortedOrder(vals,order);


const double target=0.50; // 50th percentile (median value)

int i=0;
double temp=0;

while (temp<target)
{
temp=temp+(vals[order[i]]*weightField[order[i]]*V[order[i]])/allconc;
i++;
}
scalar& res = setComponent(result, 0);
res=vals[order[i-1]];
which gives results close to what could be true but not really: I attach median and mean graphs, which are similar in trend but not in values. There is probably something wrong in the code which I can not detect, maybe it is something clear to you. I think the operations are actually made on the region, median values are below 1 as they should, but they are also wrong.



Moreover, the run crashes (after 2438 s of computational time though) for floating point exception, but this maybe is related to solver and mesh refinement issues.


I have also two other problems:
- I don't know how to give different percentiles without defining more operations, I tried by defining more components of 'result' but it does not seem to work
- More importantly, I really don't know how to run it on parallel: the distribution sorting needs to be done over all the region, it would be much more convenient to make calculations after recontructPar and reconstructParMesh (I'm using dynamic mesh, maybe this also gives some kind of issue), but I can't find how to do functionObject post-processing after the run, I guess it's something quite feasible and you probably know


Even partial solutions, guesses, or links to useful documentation/resources are welcome.


(PS I will update this reply : the solver gives some unreasonably high values of max concentration and unreasonable low (negative) values of minimum concentration, this could vanishes with a more refined mesh; however, running on parallel is still a big issue)



Giovanni
Attached Images
File Type: jpg median_myvolFieldValue.jpg (53.8 KB, 2 views)
File Type: jpg mean_myvolFieldValue.jpg (46.0 KB, 2 views)

Last edited by the_ichthyologist; October 2, 2020 at 07:32.
the_ichthyologist is offline   Reply With Quote

Old   October 3, 2020, 09:37
Default
  #4
Senior Member
 
Mark Olesen
Join Date: Mar 2009
Location: http://olesenm.github.io/
Posts: 1,001
Rep Power: 27
olesen will become famous soon enougholesen will become famous soon enough
Take a look at the forces function object for some ideas about "binning" into a histogram. There is a far bit of code to sift through, but sure you'll find something useful.
the_ichthyologist likes this.
olesen is offline   Reply With Quote

Reply

Tags
coding, modified code, modified function, openfoam, postprocess function

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
[General] Extracting ParaView Data into Python Arrays Jeffzda ParaView 19 June 11, 2020 15:54
Problem while compiling modified simpleFoam solver mattiafc OpenFOAM Programming & Development 0 May 26, 2020 20:01
Modified simpleFOAM using given Reynolds stress field K62 OpenFOAM Running, Solving & CFD 2 March 24, 2017 03:41
Modified rhoCentralFoam slip boundary fails in parallel ChrisA OpenFOAM Programming & Development 0 June 25, 2014 20:28
Modified Equation for CFX algorithm Craig Johansen CFX 0 August 27, 2004 23:02


All times are GMT -4. The time now is 16:04.