Connection of Hexpress grid and Autogrid 5 grid

Young G · November 18, 2014, 23:18

Hi guys,

I am trying to connect inlet volute grids generated by Hexpress and stage grids generated by Autogrid in Hexpress.

Structured grid can be transformed into unstructured in Hexpress, and its shape and quality seem OK. But when I try to connect the interfaces of these two parts, I mean the outlet of volute and the inlet of stage, with R/S boundary condition, it fails.

Has someone succeded in doing the similar work?

Young G · November 22, 2014, 00:03

In terms of importing the geometrical file, only Parasolid can be chosen. But .x_t file takes meter as its unit, which means my volute is 1/1000 to my stage. So I have to scale it in hexpress to match my stage.

I doubt that scaling the geometry may be the reason for the failure of creating R/S interface.

However, building a volute large enough is impossible in SOLIDWORKS, because the volute is too big, approximately 1000m long.

I do need your help.

Young G · November 24, 2014, 04:27

After being tortured by this problem for almost a week, I finally solve it.

I will note it here, in case it's helpful to others facing the same problem.

Tip 1:When you are generating the domain form geom file(.x_t), minimize the parameters as adviced by NUMECA. Precise geom will never hurt.

Tip 2: Never leave only one facet on one side of RS interface as the mannual said, neither too many!!! (It seems cutting one surface into 4 facets is also the main reason for former failure. 2 facets seems popular to this code.)

colinda1 · December 1, 2014, 03:53

Thank you for also posting your comments on how to solve it.

Indeed, when creating a domain from a parasolid file, it is good to make sure the triangulation settings are fine enough to define the geometry well. The minimum and maximum length may be divided by 100 and the curve and surface tolerances as well.

Indeed 1 face closed on itself at the rotor/stator interface is not ideal. In general I see no reason at all why 4 faces would not work. It is more likely something specific to your case that should be investigated in more detail if necessary to understand why it does not work.

But most important; it works now

Best regards,
Colinda.

Quote:

Originally Posted by Young G

After being tortured by this problem for almost a week, I finally solve it.

I will note it here, in case it's helpful to others facing the same problem.

Tip 1:When you are generating the domain form geom file(.x_t), minimize the parameters as adviced by NUMECA. Precise geom will never hurt.

Tip 2: Never leave only one facet on one side of RS interface as the mannual said, neither too many!!! (It seems cutting one surface into 4 facets is also the main reason for former failure. 2 facets seems popular to this code.)

November 18, 2014, 23:18	Connection of Hexpress grid and Autogrid 5 grid	#1
Young G New Member Join Date: Apr 2014 Posts: 13 Rep Power: 12	Hi guys, I am trying to connect inlet volute grids generated by Hexpress and stage grids generated by Autogrid in Hexpress. Structured grid can be transformed into unstructured in Hexpress, and its shape and quality seem OK. But when I try to connect the interfaces of these two parts, I mean the outlet of volute and the inlet of stage, with R/S boundary condition, it fails. Has someone succeded in doing the similar work?

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November 22, 2014, 00:03		#2
Young G New Member Join Date: Apr 2014 Posts: 13 Rep Power: 12	In terms of importing the geometrical file, only Parasolid can be chosen. But .x_t file takes meter as its unit, which means my volute is 1/1000 to my stage. So I have to scale it in hexpress to match my stage. I doubt that scaling the geometry may be the reason for the failure of creating R/S interface. However, building a volute large enough is impossible in SOLIDWORKS, because the volute is too big, approximately 1000m long. I do need your help.

November 24, 2014, 04:27		#3
Young G New Member Join Date: Apr 2014 Posts: 13 Rep Power: 12	After being tortured by this problem for almost a week, I finally solve it. I will note it here, in case it's helpful to others facing the same problem. Tip 1:When you are generating the domain form geom file(.x_t), minimize the parameters as adviced by NUMECA. Precise geom will never hurt. Tip 2: Never leave only one facet on one side of RS interface as the mannual said, neither too many!!! (It seems cutting one surface into 4 facets is also the main reason for former failure. 2 facets seems popular to this code.)