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RE: ERROR : network is not orthogonal

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ERROR : network is not orthogonal
unstructured mesh irregular grid
Answer (Unmark)
11/28/17 4:29 AM
Hi,

I am using Flexible Mesh for modelling tidal currents. I have generated irregular/unstructured grids from a polygon, and set up boundary conditions and initial conditions. I ran the model and immediately received the following error.

** ERROR : network is not orthogonal

I used RGFGRID's feature to orthogonalise grids, and re-ran the model. I received the same error again!

Could you please give me suggestion to resolve this issue?

Thanks,
Reza
RE: ERROR : network is not orthogonal
Answer (Unmark)
12/3/17 4:37 PMas a reply to Reza Shafiei.
Dear Reza,

Preparing a proper network is indeed very challenging task and often requires many extra steps.

First of all I would like to refer you to the ScreenCast to the one called: Advanced Grid generation Unstructured Grids for the Sand Engine
Please note that these screen-casts were prepared in the older version and some of the names could be different.

Secondly as described in the Delft3D User Manual and RGFGRID User Manual the ortogonalize action may require more than one running and modification of some settings. This depends on your grid, polygon in which you created a grid, grid complexity etc.

Now concerning issue you are reporting.
Did you inspect your network? Does the orthogonality of your network is around preferred 0.01 or perhaps you exceed the threshold of 0.5? Did you run any extra steps or you execute 'Orthogonalize" operation only once without any modifications?

My suggestion is following:
- Please follow the ScreenCast and check out the manuals.
- Afterwords use the option "Orthogonalize" with perhaps extra actions of "Flip edges" and "Merge Circumcenters" to avoid so-called small flow links.
- If needed run again "Orthogonalize" operations or modified the settings for orthogonalization

Please let us know if you got any further after following the suggestions above.

Kind regards,
Michal
RE: ERROR : network is not orthogonal
Answer (Unmark)
12/8/17 3:32 AMas a reply to Michal Kleczek.
I went through the following process which resolved my issue.

1- Instead of generating grids from polygon, I generated grids from splines
2- Converted regular grids to irregular
3- Orthogonalised grids

Done!