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Model wont run - errors/not orthogonal

U
Anonymous, modified 3 Years ago.

Model wont run - errors/not orthogonal

Posts: 1
Hi,

I'm new to using Delft 3d flexible mesh and am just trying to get a simple model running.
I made a grid for my area (SWgridx_net.nc) which when I went to orthogonise came up with a node highlighted in yellow and an error message (pic1).
I couldn't figure out what was wrong and tried fixing it but only thing that allowed me to orthogonise the grid that I could work out was to just delete the offending point, I then added a bed level (.xyz file) and the mesh saved from this grid and bed level (grid28617finish.nc) is shown in pic2. But when i go to run the model it comes up with an error saying not orthogonal (pic3).
What can I do to fix this and get the model to run?

Thanks,Lucy
delft3d flexible mesh orthogonality error

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JZ
Jing Zhao, modified 3 Years ago.

RE: Model wont run - errors/not orthogonal (Answer)

Padawan Posts: 29 Join Date: 7/12/16 Recent Posts
Dear Lucy,

As mentioned in the User Manual, orthogonality is very important for accuracy: advised orthogonality values for your grid are around 0.01. The current threshold is 0.5, already quite high.

You could use RGFGRID to improve your grid orthogonality. You need to make the grid orthogonality satisfied before running the model.

Kind regards,

Jing Zhao

Deltares
LT
Lucy Tilsley, modified 3 Years ago.

RE: Model wont run - errors/not orthogonal

Youngling Posts: 3 Join Date: 6/28/17 Recent Posts
Ok, thanks I'll try to improve the orthogonality

Thanks
Lucy
CG
Camille Grimaldi, modified 2 Years ago.

RE: Model wont run - errors/not orthogonal

Youngling Posts: 1 Join Date: 5/28/18 Recent Posts

Hi Jing, 

I have the same error but I don't see what I need to fix as my grid's orthogonality is 0.01 everywhere (see attached). Any idea of where else that could come from?

Thanks,

Camille

Attachments:

MK
Michal Kleczek, modified 2 Years ago.

RE: Model wont run - errors/not orthogonal

Padawan Posts: 53 Join Date: 10/23/14 Recent Posts

Dear Camille,

I had a short look at your problem and network that you shared with us. Indeed the error is rather confusing since orthogonality is good. There is, however, another problem with your network and that is so-called 'small flow-link'. If you open your network in RGFGRID and you go to the View -> Grid Properties there is an option to view 'Circumcenters are too close' (you may need a newer version of our software with a newer RGFGRID, depending on a version you are currently using). There are four (actually eight) 'corner' cells that have too close circumcenters and as a follow-up a small flow-link (connection between cirumcenters). You should have these points highlighted.
To fix that you should go in the RGFGRID to the Operations -> Grid -> Merge Circumcenters

Please note I have attached a picture on one of the 'corners' that is corrected (automatically removed netlink after using option above).

I hope that will help you to move forward with your model.

Kind regards,
Michal Kleczek, Deltares

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