The confusion of the meanings of `patchi` and `facei`

Gareth_CN · November 15, 2021, 21:29

Hello,

I have some doubts about the meaning of these two parameters: patchi and facei.
In my understanding, `patchi` points to the sequence number of boundary, for example 'INLET', and `facei` points to the sequence number of each mesh face on the 'INLET' boundary.

Is there something wrong with my understanding? Hope someone could give me some advice.

All regards!

Gareth

olesen · November 20, 2021, 06:01

It is even simpler than you think. In most (all?) places these are simply local loop variables. Instead of writing a loop "for (int i=...)" and another loop with "for (int j=...)" and then trying to remember what "i" and "j" represent within the loops, they are given more meaning names. Eg, "for (int patchi=...)" etc.

The next part is of course what you are indexing into. The patches are arranged internally as a list. All "normal" patches in the same sequence on all processors, followed by all of the processor-processor communication patches (obviously not the same on all processors). There is also a level of redundancy built in. Each patch also has an index() value, so it knows where it is located in the list.

Gareth_CN · November 22, 2021, 02:37

Hello Olesen!
Thank you very much for your precise advice. I will look into it.

Gareth

November 15, 2021, 21:29	The confusion of the meanings of `patchi` and `facei`	#1
Gareth_CN New Member Zhang Qibo Join Date: Oct 2021 Posts: 7 Rep Power: 4	Hello, I have some doubts about the meaning of these two parameters: patchi and facei. In my understanding, `patchi` points to the sequence number of boundary, for example 'INLET', and `facei` points to the sequence number of each mesh face on the 'INLET' boundary. Is there something wrong with my understanding? Hope someone could give me some advice. All regards! Gareth

November 20, 2021, 06:01		#2
olesen Senior Member Mark Olesen Join Date: Mar 2009 Location: https://olesenm.github.io/ Posts: 1,686 Rep Power: 40	It is even simpler than you think. In most (all?) places these are simply local loop variables. Instead of writing a loop "for (int i=...)" and another loop with "for (int j=...)" and then trying to remember what "i" and "j" represent within the loops, they are given more meaning names. Eg, "for (int patchi=...)" etc. The next part is of course what you are indexing into. The patches are arranged internally as a list. All "normal" patches in the same sequence on all processors, followed by all of the processor-processor communication patches (obviously not the same on all processors). There is also a level of redundancy built in. Each patch also has an index() value, so it knows where it is located in the list.

November 22, 2021, 02:37		#3
Gareth_CN New Member Zhang Qibo Join Date: Oct 2021 Posts: 7 Rep Power: 4	Hello Olesen! Thank you very much for your precise advice. I will look into it. Gareth