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TOPIC: boundary conditions

boundary conditions 8 years 3 months ago #23034

  • shahirah
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hi everyone,

i'am a beginner in this field and hopefully someone can explain in detail the steps for setting the boundary.

i have been followed the tutorial manual of blue kenue for my mesh(estuary). and luckily my mesh works in telemac2d but the velocity result is zero. is it my boundary condition setting is wrong because i had go through back to the manual it also said that the boundary code for LIHBOR (for depth), LIUBOR (for velocity u), LIVBOR (for velocity v) can be define manually. by editing the HBOR, UBOR and VBOR perhaps??? or just left it to be zero??


regards

shahirah
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boundary conditions 8 years 3 months ago #23037

  • shahirah
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here with attach my work for your comments.
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boundary conditions 8 years 3 months ago #23038

  • shahirah
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here with also attach my work for your comments.
Attachments:
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boundary conditions 8 years 3 months ago #23041

  • jmhervouet
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Hello,

Pahang sounds like a state in Malaysia... kamu dapat berbahasa Malaysia ? Apa kabar? selamat pagi! (tetapi saya dapat berbahasa sedikit sedikit saja...).

I looked at your boundary conditions file and it looks correct with an exit (5 4 4) as boundary 1 and an entrance as boundary 2 (4 5 5). You can let 0. for HBOR, UBOR and VBOR if you then use keywords like PRESCRIBED DISCHARGES=...

However in your case you want to use the tpxo database and this requires to have prescribed velocities, not discharges, thus 4 6 6 instead of 4 5 5. It is also recommended in this case to use the Thompson's boundary conditions, hence:

OPTION FOR LIQUID BOUNDARIES : 1;2

it is set here for your boundary 2, that I suppose to be the offshore boundary. It is probable that you should even use 5 6 6 instead of 4 5 5 (thus prescribing elevation and velocity, that will be provided by tpxo, and then the Thompson's theory will select what is relevant following the theory of characteristics). Also check what is your boundary 1 declared as an exit, if it true you should give at least PRESCRIBED ELEVATIONS = ...

With best regards,

Jean-Michel Hervouet
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boundary conditions 8 years 3 months ago #23080

  • shahirah
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hi Jean-Michel Hervouet,

selamat pagi, saya khabar baik. and i'm malaysian and my 1st language was bahasa Melayu (Malaysia). yup Malaysia..Pahang is one of state in Malaysia.


i will try with your tips. hopefully it works..

thanks
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boundary conditions 8 years 3 months ago #23179

  • Don
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hello there Jean-Michel Hervouet,

im actually facing the same problem as Shahirah where when i run the simulation,,there is no velocity observation.

im trying to do a coastal current simulation with TIDES as its only forcing. I did mentioned my tide.txt in the steering file but still there is no velocity observation.

Previously, before adding the "MAXIMUM NUMBER OF ITERATIONS FOR SOLVER: 60000" my model would fail and end with "exceeding maximum iteration" .
I suspect there is some problem with my steering file and i did test with some factors like the "imlpication for velocity/depth", "diffusion coefficant", "solver accuracy" and etc to increase the stability but would still fail.


Please bare with me because im still very new with this software. Really hope you could help me too...Thanks

Don
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