# Grid I Unit Normal and Grid J Unit Normal

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 July 29, 2017, 15:20 Grid I Unit Normal and Grid J Unit Normal #1 New Member   Join Date: Jul 2017 Posts: 3 Rep Power: 8 What is the difference between “Grid I Unit Normal”, “Grid J Unit Normal” and “Grid K Unit Normal”? In 'Tecplot-> Analyze -> Calculate Variable' there are three types of Unit Normals listed namely "Grid I Unit Normal", "Grid J Unit Normal" and "Grid K Unit Normal". I want to know the difference between them! Thanks and Regards

 July 31, 2017, 16:41 #2 Senior Member   Scott Fowler Join Date: May 2009 Posts: 112 Rep Power: 16 These are unit normals that point normal to the I-, J- or K-plane, in the plus-index direction. Appendix section F-3.1 briefly discusses these, but makes no mention of meaning or behavior for FE zones. Only Grid K Unit Normal is meaningful for finite element surface zones; the direction it points is determined by cell right-hand rule. Regards, Scott

July 31, 2017, 17:37
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Although if you find anything regarding meaning of 'Grid I Unit Normal' and 'Grid J Unit Normal' please let me know.

Thanks and Regards
pawansut

Quote:
 Originally Posted by wsfowler These are unit normals that point normal to the I-, J- or K-plane, in the plus-index direction. Appendix section F-3.1 briefly discusses these, but makes no mention of meaning or behavior for FE zones. Only Grid K Unit Normal is meaningful for finite element surface zones; the direction it points is determined by cell right-hand rule. Regards, Scott

 July 31, 2017, 19:00 #4 Senior Member   Scott Fowler Join Date: May 2009 Posts: 112 Rep Power: 16 Grid I Unit Normal and Grid J Unit Normal are only meaningful for structured grids. They represent the normal in the positive I- and J- directions respectively. Grid K Unit Normal is meaningful for both structured and unstructured grids. For structured grids it is the normal in the positive K- direction. For unstructured grids it is the normal for surface cells (triangles & quads) in the direction determined by the right-hand rule. Hopefully that provides a more explicit definition for you. pawansut likes this.

July 31, 2017, 19:14
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Scott: Yes! Indeed. Thanks a lot.
I needed this explanation.

Thanks and Regards
pawansut

Quote:
 Originally Posted by wsfowler Grid I Unit Normal and Grid J Unit Normal are only meaningful for structured grids. They represent the normal in the positive I- and J- directions respectively. Grid K Unit Normal is meaningful for both structured and unstructured grids. For structured grids it is the normal in the positive K- direction. For unstructured grids it is the normal for surface cells (triangles & quads) in the direction determined by the right-hand rule. Hopefully that provides a more explicit definition for you.