Understanding Code behind BCs

Linse · October 28, 2011, 06:30

What do the Code parts of the BCs actually do?

While there already are several implemented boundary conditions and while groovyBC helps with even extending the range of BCs, sometimes it is necessary to do own BCs.

By now this is the case for me as well.
I will have to implement some boundary conditions even groovyBC is not capable of. Therefore I really need to understand how the BCs work, how/where from they get their values, how/where to they write the values to the fields after they maybe have changed them, how the changes of the values take place inside the BC...

I hope somebody can tell me a good starting point for understanding how the BCs work in the code-way. Maybe even the place of a very basic (and extensively commented?) BC would be enough...

To all: Feel free to add further questions on the code of the BCs and particularly the answers will be welcome!
Nevertheless, please avoid questions on the physics side of the BCs, as there are other threads for these!

ata · October 29, 2011, 02:20

Hi
See
/opt/openfoam201/src/finiteVolume/fields/fvPatchFields/basic/fixedValue
Good luck

Ata

Linse · November 3, 2011, 17:43

Hi Ata!

Thank you already by now!
This point truly is a good starting point for understanding the structure of the BCs!

Ola Widlund · November 29, 2011, 03:33

Hi,

I guess you're an expert on BC:s by now, but anyway....

What I did the first time was to copy a bc class that inherits from either fixedValue or mixed (depending on what is closest to your needs), then do search-replace on the calss name to make it your own. There are plenty of bc:s in the library that inherit and build on the basic classes. From there it's easy to see where in the code things are done.

Other complex bc:s also contain a lot of useful code snippets you could reuse. For example how to look up values of other fields, read variable settings from the dictionary of the bc, etc.

/Ola

Linse · November 30, 2011, 08:17

Hi Ola,
actually, I am not yet much more advanced concerning BCs.
I have the luxury of having several open problems to solve, so I first decided to work on two other major points while waiting for additional answers in this thread. ;-)

Thank you (and all who will follow with giving further enlightening answers!) for your answers and assistance!

kdneroorkar · November 30, 2011, 09:13

I have a pdf document that I had made some time back for explaining how boundary conditions are implemented in OpenFOAM. I can send it to you if you give me your email address

jack zhou · December 13, 2011, 09:40

Quote:

Originally Posted by kdneroorkar

I have a pdf document that I had made some time back for explaining how boundary conditions are implemented in OpenFOAM. I can send it to you if you give me your email address

would you like to give me another copy?my E-address is mezjr@foxmail.com.
Thanks,
jack Zhou

andyru · January 8, 2012, 04:48

Hellokshitij ,

could you send me your bc-pdf too? I'm currently working on a internalfixedvalue-problem...

Thanks in advance

Andy

kdneroorkar · January 9, 2012, 08:58

Hi Andy
can you please send me your email address, mine is kdneroorkar(at)gmail.com
Thanks
Kshitij

October 28, 2011, 06:30	Understanding Code behind BCs	#1
Linse Senior Member Bernhard Linseisen Join Date: May 2010 Location: Heilbronn Posts: 183 Blog Entries: 1 Rep Power: 15	What do the Code parts of the BCs actually do? While there already are several implemented boundary conditions and while groovyBC helps with even extending the range of BCs, sometimes it is necessary to do own BCs. By now this is the case for me as well. I will have to implement some boundary conditions even groovyBC is not capable of. Therefore I really need to understand how the BCs work, how/where from they get their values, how/where to they write the values to the fields after they maybe have changed them, how the changes of the values take place inside the BC... I hope somebody can tell me a good starting point for understanding how the BCs work in the code-way. Maybe even the place of a very basic (and extensively commented?) BC would be enough... To all: Feel free to add further questions on the code of the BCs and particularly the answers will be welcome! Nevertheless, please avoid questions on the physics side of the BCs, as there are other threads for these!

November 30, 2011, 09:13	Hi Linse	#6
kdneroorkar Member kshitij neroorkar Join Date: Mar 2009 Location: Michigan, USA Posts: 32 Rep Power: 17	I have a pdf document that I had made some time back for explaining how boundary conditions are implemented in OpenFOAM. I can send it to you if you give me your email address

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October 29, 2011, 02:20		#2
ata Senior Member ata kamyabi Join Date: Aug 2009 Location: Kerman Posts: 323 Rep Power: 17	Hi See /opt/openfoam201/src/finiteVolume/fields/fvPatchFields/basic/fixedValue Good luck Ata

November 3, 2011, 17:43		#3
Linse Senior Member Bernhard Linseisen Join Date: May 2010 Location: Heilbronn Posts: 183 Blog Entries: 1 Rep Power: 15	Hi Ata! Thank you already by now! This point truly is a good starting point for understanding the structure of the BCs!

November 29, 2011, 03:33		#4
Ola Widlund New Member Ola Widlund Join Date: Jun 2011 Location: Sweden Posts: 13 Rep Power: 14	Hi, I guess you're an expert on BC:s by now, but anyway.... What I did the first time was to copy a bc class that inherits from either fixedValue or mixed (depending on what is closest to your needs), then do search-replace on the calss name to make it your own. There are plenty of bc:s in the library that inherit and build on the basic classes. From there it's easy to see where in the code things are done. Other complex bc:s also contain a lot of useful code snippets you could reuse. For example how to look up values of other fields, read variable settings from the dictionary of the bc, etc. /Ola

November 30, 2011, 08:17		#5
Linse Senior Member Bernhard Linseisen Join Date: May 2010 Location: Heilbronn Posts: 183 Blog Entries: 1 Rep Power: 15	Hi Ola, actually, I am not yet much more advanced concerning BCs. I have the luxury of having several open problems to solve, so I first decided to work on two other major points while waiting for additional answers in this thread. ;-) Thank you (and all who will follow with giving further enlightening answers!) for your answers and assistance!

January 8, 2012, 04:48		#8
andyru Member Andreas Ruopp Join Date: Aug 2009 Location: Stuttgart / Germany Posts: 31 Rep Power: 16	Hellokshitij , could you send me your bc-pdf too? I'm currently working on a internalfixedvalue-problem... Thanks in advance Andy

January 9, 2012, 08:58		#9
kdneroorkar Member kshitij neroorkar Join Date: Mar 2009 Location: Michigan, USA Posts: 32 Rep Power: 17	Hi Andy can you please send me your email address, mine is kdneroorkar(at)gmail.com Thanks Kshitij