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Dear all,
I am using Telemac 3D, v8p1.
I am running a simple lake model and coupling with Waqtel for Full Balance heat exchange model (WATER QUALITY PROCESS = 11).
From the values given in the output for Mass Balance (in the sortie file, FINAL MASS BALANCE), I have noticed that for the tracer TEMPERATURE, MASS LOSS is always a high percentage of the initial mass (i.e. 70%).
This problem does not seem to relate to numerical issues. Instead, it seems that it is related to the solar radiation or sun ray flux RS component of the heat exchange model. In particular, ERROR ON THE MASS DURING THIS TIME STEP is always peaking during the midday hours while is goes almost zero during night hours (lets say from 20:00 to 05:00).
Further, the peaking of this error is always combined with the daily peak of the MASS AT THE PRESENT TIME STEP.



Could this be an error of the Mass Balance? Could it be possible that the mass balance of Telemac does not account for the heat flux from sun ray flux RS component and identifies it as a Mass Loss (negative, which means that the mass of the model is rising and this cannot be assigned to any mass inflow components)?
Any ideas?
Thanks in advance,
All the best,
Alexandros

Hello Alexandros,

Which release of v8p1 are you using? v8p1r0 or the latest v8p1r1?

In release v8p1r1, a bug for the computation of the mass-balance for tracers has been solved in the BIL3D subroutine to take into account volumetric explicit source terms (which is the case of the solar radiation).

Hope this helps,

Chi-Tuan

Chi-Tuan, hi,

Indeed, I’ve been using v8p1r0.

I have updated to v8p1r1. Now the mass balance seems to be calculated correctly and the mass loss is close to 0.

So, problem solved!

Thanks a lot for the help, and much appreciate the quick response.
Best,
Alexandros