change BC during a run but the BC isn't implemented

joshmccraney · April 30, 2020, 20:10

Hi FOAMers!

A tank partially filled with liquid is being drained in interFoam. After 10 seconds, I would like the drain rate to change. To do this, I run the simulation for 10 seconds, then edit the 0/U BC file, and execute " mpirun -np 16 interFoam -parallel "

The issue is the initial boundary condition I specified at the beginning of the run is still being used, as if OpenFOAM does not realize I edited the U file. What command do I need to add? At the beginning of the simulation I run the following

Code:

rm -r postProcessing
rm -r processor*
rm 0/alpha.water
rm constant/dynamicMeshDict
cp -r ../mesh/constant/polyMesh constant
cp dynamicMeshDict_refine constant/dynamicMeshDict
setFields
decomposePar
mpirun -np 16 interFoam -parallel

Thanks so much for your time!

clapointe · April 30, 2020, 23:09

Assuming that you are starting from that 10s mark (with startFrom latestTime), you will need to edit the bc in the 10/U file -- the 0/U file will not be read, as you've found out. This could be a bit tricky since you're running in parallel. I'm not sure of the best way to go about this -- and someone should jump in if they do -- but off the top of my head you'll either need to edit the decomposed processor*/U file(s) or perhaps you could reconstruct, edit 10/U, and then decompose again.

Caelan

joshmccraney · May 1, 2020, 03:22

Quote:

Originally Posted by clapointe

Assuming that you are starting from that 10s mark (with startFrom latestTime), you will need to edit the bc in the 10/U file -- the 0/U file will not be read, as you've found out. This could be a bit tricky since you're running in parallel. I'm not sure of the best way to go about this -- and someone should jump in if they do -- but off the top of my head you'll either need to edit the decomposed processor*/U file(s) or perhaps you could reconstruct, edit 10/U, and then decompose again.

Caelan

I think I'll have to reconstructPar, sadly. The 10/U file looks nothing like the 0/U (a lot of vectors, and the format looks very strange). Thanks for the reply Caelan!

If anyone else has suggestions I'm all ears.

Yann · May 1, 2020, 05:47

Hello,

You can manually edit the processorN/10/U files with a for loop to udpate your boundary condition in every processor directories. BUT, you should check first what writeFormat you are using in your controlDict. It should be set to ascii, since obviously you won't be able to manually modify binary files.

Another way around is to use the changeDictionary utility. I never used it for this specific case but it should do the job, using the option -latestTime in order to update the files in the last time steep.

Cheers,
Yann

April 30, 2020, 20:10	change a BC during a run	#1
joshmccraney Senior Member Josh McCraney Join Date: Jun 2018 Posts: 220 Rep Power: 9	Hi FOAMers! A tank partially filled with liquid is being drained in interFoam. After 10 seconds, I would like the drain rate to change. To do this, I run the simulation for 10 seconds, then edit the 0/U BC file, and execute " mpirun -np 16 interFoam -parallel " The issue is the initial boundary condition I specified at the beginning of the run is still being used, as if OpenFOAM does not realize I edited the U file. What command do I need to add? At the beginning of the simulation I run the following Code: rm -r postProcessing rm -r processor* rm 0/alpha.water rm constant/dynamicMeshDict cp -r ../mesh/constant/polyMesh constant cp dynamicMeshDict_refine constant/dynamicMeshDict setFields decomposePar mpirun -np 16 interFoam -parallel Thanks so much for your time! Last edited by joshmccraney; April 30, 2020 at 22:18.

April 30, 2020, 23:09		#2
clapointe Senior Member Join Date: Aug 2015 Posts: 494 Rep Power: 15	Assuming that you are starting from that 10s mark (with startFrom latestTime), you will need to edit the bc in the 10/U file -- the 0/U file will not be read, as you've found out. This could be a bit tricky since you're running in parallel. I'm not sure of the best way to go about this -- and someone should jump in if they do -- but off the top of my head you'll either need to edit the decomposed processor*/U file(s) or perhaps you could reconstruct, edit 10/U, and then decompose again. Caelan joshmccraney likes this.

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May 1, 2020, 05:47		#4
Yann Senior Member Yann Join Date: Apr 2012 Location: France Posts: 1,223 Rep Power: 28	Hello, You can manually edit the processorN/10/U files with a for loop to udpate your boundary condition in every processor directories. BUT, you should check first what writeFormat you are using in your controlDict. It should be set to ascii, since obviously you won't be able to manually modify binary files. Another way around is to use the changeDictionary utility. I never used it for this specific case but it should do the job, using the option -latestTime in order to update the files in the last time steep. Cheers, Yann