TELEMAC-MASCARET Forum: Tracer die-off in SOURCE

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TOPIC: Tracer die-off in SOURCE_TRAC

Tracer die-off in SOURCE_TRAC 10 years 2 months ago #14065

hydroenvironmental OFFLINE Senior Boarder Posts: 137 Thank you received: 32	Hi , I have tried to program a simple uniform (in depth) exponential die-off rate in the User program SOURCE_TRAC for tracer 1. My programming appears not to be correct and would appreciate any assistance. Regards Tony File Attachment: File Name: TCSource1.f File Size: 3 KB
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Tracer die-off in SOURCE_TRAC 10 years 2 months ago #14066

c.coulet
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Hi Tony

Maybe i'm wrong in the comprehension of you problem, but I think you're complexify a lot your problem.
You have the example with the decay in this source which is working well so I think you could use it directly with only a modification of K.
You could have a look in the Telemac2d where this functionality has been implemented in the default version (with dedicated keyword).

Just a strange point in your program, you modify SOTA and S1TA.
S0TA is for the explicit part of the source, S1TA for the implicit one. In such case, you should use only the implicit part...

Hope this helps

Christophe

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Tracer die-off in SOURCE_TRAC 10 years 2 months ago #14067

hydroenvironmental OFFLINE Senior Boarder Posts: 137 Thank you received: 32	Yes you are correct the example given works but was trying to program it my self so that I may do more complex problems I was trying to have the decay term time centered but I am possibly misunderstanding how to do this and any advice would help
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Tracer die-off in SOURCE_TRAC 10 years 2 months ago #14068

c.coulet OFFLINE Moderator Posts: 3722 Thank you received: 1031	Could you explain what you mean by "decay term time centered"?
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Tracer die-off in SOURCE_TRAC 10 years 2 months ago #14069

hydroenvironmental OFFLINE Senior Boarder Posts: 137 Thank you received: 32	The exponential decay term in the transport dispersion eqn is KC (C tracer concentration and K the decay rate) where = K(t)C(t)/2. (explicit term) + K(t+1)C(t+1)/2(implicit term) and K may be influenced by other tracer concentrations such as Temp, salinity etc. regards Tony
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Tracer die-off in SOURCE_TRAC 10 years 2 months ago #14076

c.coulet OFFLINE Moderator Posts: 3722 Thank you received: 1031	Hi Not sure but as I understand, with a given value for T90 (time for 90% of decay), you should compute K = -2.3/T90/3600 Then you just have to modify the call OS CALL OS('X=C ',S1TA%ADR(1)%P,C=K/2) for implicit part CALL OS('X=C ',S0TA%ADR(1)%P,C=K/2) for explicit part In TELEMAC2D, you should multiply these quantities by HPROP but I think it's not necessary in TELEMAC-3D Hope this helps
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Tracer die-off in SOURCE_TRAC 10 years 2 months ago #14077

hydroenvironmental
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Posts: 137
Thank you received: 32

Thanks Christophe,
I have tried this coding earlier but does not work when I include the Explicit part (I have played around with the sign convention of K also)
CALL OS('X=C ',S1TA%ADR(1)%P,C=K/2) for implicit part
CALL OS('X=C ',S0TA%ADR(1)%P,C=K/2) for explicit part

I can get it to Work correctly for the fully implicit case
with K = +2.3/T90/3600 using the function CALL OS('X=C ',S1TA%ADR(1)%P,C=K).
Perhaps this is the only way that it can be handled in Telemac3d?

From examples I have seen earlier in Telemac2d the treatment of the SOTA term is different and not a mirror image of the S1TA term that works above.

kind regards
Tony

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