Position of cells in a orthogonal grid

alberto · February 5, 2008, 21:31

Hello,

I'm using a structured (orthogonal squared cells) grid, and I need to implement an algorithm which requires the values of a variable in the "above"/"below", "left"/"right", "front"/"back" cells.

Is there a quick way to identify these cells?

niklas · February 6, 2008, 03:01

short answer: hmmm, sort of.

The fastest way as I see it is to access all the faces, check their face-normals and depending on their direction determine if they are left or right, et c.
from that create a mapping of left -> face i, right -> face j, et c.
(which of course require some mesh class hacking)

you probably only need to do this once for a static mesh and after this it should be fast.

alberto · February 6, 2008, 12:28

Hmmm. Thanks for your reply Niklas.

I have a doubt on how the boundary cells are managed. I mean, I have 4 neighbours for the "internal" cells, but only 2 or 3 for the boundary cells, which are exceptions because they have one or more lacking "directions".

How that procedure can identify them?

Regards,
Alberto

February 5, 2008, 21:31	Hello, I'm using a structur	#1
alberto Senior Member Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,912 Rep Power: 36	Hello, I'm using a structured (orthogonal squared cells) grid, and I need to implement an algorithm which requires the values of a variable in the "above"/"below", "left"/"right", "front"/"back" cells. Is there a quick way to identify these cells? __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

February 6, 2008, 03:01	short answer: hmmm, sort of.	#2
niklas Super Moderator Niklas Nordin Join Date: Mar 2009 Location: Stockholm, Sweden Posts: 693 Rep Power: 29	short answer: hmmm, sort of. The fastest way as I see it is to access all the faces, check their face-normals and depending on their direction determine if they are left or right, et c. from that create a mapping of left -> face i, right -> face j, et c. (which of course require some mesh class hacking) you probably only need to do this once for a static mesh and after this it should be fast.

February 6, 2008, 12:28	Hmmm. Thanks for your reply Ni	#3
alberto Senior Member Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,912 Rep Power: 36	Hmmm. Thanks for your reply Niklas. I have a doubt on how the boundary cells are managed. I mean, I have 4 neighbours for the "internal" cells, but only 2 or 3 for the boundary cells, which are exceptions because they have one or more lacking "directions". How that procedure can identify them? Regards, Alberto __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

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