Topology and Geometry

July 11, 2002, 10:32

Hi,

In a multiblock topology (5 blocks) , how can I know wich direction correspond to X axis or Y axis or Zaxis for each block ?

Once I know the direcion in one block, I could find the direction in the other blocks using pointer from face to node. But, till know I didn't find the way for guessing the direction in first block.

Thanks

July 11, 2002, 16:10

Hi Fred,
I can say that there's two different things, spatial coordinates and nodal coordinates. The spatial coordinates (X, Y, Z) you know from your CAD model. The nodal coodinates (I, J, K) are made on the pre-processor. In a multiblock grid you just can't know if the I direction will be parallel to X direction. One thing I'd suggest you is to check this out using the post-processor. Which post-processor are you using, Analyse? And, what you're intending to do with those blocks?
Regards, cfd guy

July 15, 2002, 09:57

Did you use CFX Build to generate your Blocks ? If so you can turn on some of the display functions which show the orientation of the Blocks. I can't remember the exact menu you need but its not hard to find. Bob

July 15, 2002, 10:09

I believe you are looking for the ijk triad Bob

July 17, 2002, 05:46

Hello Bob, Hello cfd guy

Thanks a lot for your answers.

Geometry is built within cfx build. It is very complex (about 13 blokcs). I have to fix an incomming flux from "above" in all cells. That is he reason why I have to know where is the vertical direction for each block. Using Analyse facilities I saw that i-j-k triad may be diferent in each block but also left handed.

Since "my" geometry involves many blocks, i try to do this automatically.

Till know, I do what follows : 1/ At first call of ustrn making an inventory of all blocks and locating block's vertical direction. 2/ Using user subroutine blkijk to see at which block the cell belongs and therefore the vertical direction.

This seems quite heavy and I would like to know if there is an easier (more clever) way to do this, such a pointer for instance...

Bye.

Fred

July 17, 2002, 11:06

Hi Fred, so are you saying that in every cell you want a Flux entering the cell across the High K face ? Bob

July 19, 2002, 04:53

Hi Bob

Yes.

July 11, 2002, 10:32	Topology and Geometry	#1
Fred Guest Posts: n/a	Hi, In a multiblock topology (5 blocks) , how can I know wich direction correspond to X axis or Y axis or Zaxis for each block ? Once I know the direcion in one block, I could find the direction in the other blocks using pointer from face to node. But, till know I didn't find the way for guessing the direction in first block. Thanks

July 11, 2002, 16:10	Re: Topology and Geometry	#2
cfd guy Guest Posts: n/a	Hi Fred, I can say that there's two different things, spatial coordinates and nodal coordinates. The spatial coordinates (X, Y, Z) you know from your CAD model. The nodal coodinates (I, J, K) are made on the pre-processor. In a multiblock grid you just can't know if the I direction will be parallel to X direction. One thing I'd suggest you is to check this out using the post-processor. Which post-processor are you using, Analyse? And, what you're intending to do with those blocks? Regards, cfd guy

July 15, 2002, 09:57	Re: Topology and Geometry	#3
Bob Guest Posts: n/a	Did you use CFX Build to generate your Blocks ? If so you can turn on some of the display functions which show the orientation of the Blocks. I can't remember the exact menu you need but its not hard to find. Bob

July 15, 2002, 10:09	Re: Topology and Geometry	#4
Bob! Guest Posts: n/a	I believe you are looking for the ijk triad Bob

July 17, 2002, 05:46	Re: Topology and Geometry	#5
Fred Guest Posts: n/a	Hello Bob, Hello cfd guy Thanks a lot for your answers. Geometry is built within cfx build. It is very complex (about 13 blokcs). I have to fix an incomming flux from "above" in all cells. That is he reason why I have to know where is the vertical direction for each block. Using Analyse facilities I saw that i-j-k triad may be diferent in each block but also left handed. Since "my" geometry involves many blocks, i try to do this automatically. Till know, I do what follows : 1/ At first call of ustrn making an inventory of all blocks and locating block's vertical direction. 2/ Using user subroutine blkijk to see at which block the cell belongs and therefore the vertical direction. This seems quite heavy and I would like to know if there is an easier (more clever) way to do this, such a pointer for instance... Bye. Fred

July 17, 2002, 11:06	Re: Topology and Geometry	#6
Bob Guest Posts: n/a	Hi Fred, so are you saying that in every cell you want a Flux entering the cell across the High K face ? Bob

July 19, 2002, 04:53	Re: Topology and Geometry	#7
Fred Guest Posts: n/a	Hi Bob Yes.

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