CFD Online Discussion Forums

CFD Online Discussion Forums (
-   CFX (
-   -   Topology and Geometry (

Fred July 11, 2002 09:32

Topology and Geometry

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.


cfd guy July 11, 2002 15:10

Re: Topology and Geometry
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

Bob July 15, 2002 08:57

Re: Topology and Geometry
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

Bob! July 15, 2002 09:09

Re: Topology and Geometry
I believe you are looking for the ijk triad Bob

Fred July 17, 2002 04:46

Re: Topology and Geometry
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...



Bob July 17, 2002 10:06

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

Fred July 19, 2002 03:53

Re: Topology and Geometry
Hi Bob


All times are GMT -4. The time now is 20:46.