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TOPIC: downstream and upstream

downstream and upstream 6 years 5 months ago #30479

  • jonatan
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hello
i have two boundaries. How to define ustream and downstream in telemac2d ? is there a keyword ?
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downstream and upstream 6 years 5 months ago #30482

  • riadh
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Hello

The order is defined based on the order of appearence in the boundary condition file (.cli).
Ohterwise, if you run your case, Telemac will write in the first steps of the listing header how many solid and liquid boundaries in the domain with their order.

I hope this helps

with my kind regards

Riadh
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downstream and upstream 6 years 5 months ago #30486

  • jonatan
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I tried with bluekenue. But the downstream is the first in the boundary condition file. I tried to change the order of choosing the boundaries in bluekenue but the downstream is always first in the file.
Can i change it manually ?if i copy and delete the lines of downstream and paste them in the end of the file will it be okay ?
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downstream and upstream 6 years 5 months ago #30491

  • shenh
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No, you cannot change the order of boundaries in BlueKenue and there is no need to change their order. The order is dependent on the geometry of the mesh. Node numbering starts from boundary point with minimum x + y coordinate and goes anti-clockwise along the boundary. Once finished, the inner island boundary nodes are numbered in clockwise direction. However, there is a difference in which island nodes to number first between BlueKenue and Fudda (another software to generate boundary condition file). I am not sure the difference though. This difference does not impact the model results as long as your boundary usage agrees with the boundary conditions file (eg your case file and boundary conditions file both know which boundary has order 1, 2, etc).

Once numbering is done, the order of boundaries is determined. As Riadh suggested, the first open boundary has order 1, the second open boundary has order 2, and so on.

Hailiang
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downstream and upstream 6 years 5 months ago #30492

  • jonatan
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Understood. Thanks
But i still don't understand how does telemac knows the direction of flow. From boundary num 1 to boundary 2 or from boundary 2 to boubdary 1
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downstream and upstream 6 years 5 months ago #30493

  • c.coulet
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It depends on the situation.
There is no direction of the flow (from 1 to 2 or 2 to 1).
There is just water on a digital elevation model and physical process.
On earth, water goes from upper points to lower points...
Positive value given to boundary limit with impose discharge means water enter into the domain...

Regards
Christophe
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