open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

I'd like to model 2 tracers in one T2D simulation:
TRACER 1 = SALINITY
TRACER 2 = Dissolved Organic Carbon (conservative tracer)

If I set 'DENSITY EFFECTS = YES', does T2D know that this applies only to TRACER 1?

In other words, will my DOC input affect velocities in the same way that SALINITY will?

Many thanks!
Peter

Hello,

Good question, and the answer is that Telemac-3D checks the tracers names and looks for SALINIT (last letter discarded because different in French and English) and TEMPERATURE to know what is what, then the rank of salinity and temperature in the list is recorded. So be sure to give correct names of tracers in the steering files, in 32 letters, the first 16 for the name and the last 16 for the unit (but we do not check yet the units for temperature and salinity).

Best regards and nice week-end,

Jean-Michel Hervouet

Thanks!

Do you mean T3d, or T2d?

Hello,

Excuse me, I really meant Telemac-3D, I did not imagine that it was in Telemac-2D, where the salinity effects are only due to horizontal gradients, so a rather rare application (though I was told it is important in the North sea). In Telemac-2D the salinity must be the first tracer (see subroutine valro.f in library telemac2d).

Regards,

JMH

Thanks JHM,
All working now with 2 tracers, allthough I have 2 further issues:

1) Version 6 manual states (page 60) that PRESCRIBED TRACERS VALUES order is: tracer 1 at boundary 1; tracer 1 at boundary 2;...; tracer 2 at boundary 1; tracer 2 at boundary 2;...
BUT, for me (V6P1), the order is: T1 at B1; T2 at B1;...; T1 at B2; T2 at B2;...
Seen this before?

2) If I run a simulation with 2 TRACERS (SALINITY, DOC) and use COMPUTATION CONTINUED, where the PREVIOUS COMPUTATION FILE only had 1 TRACER (SALINITY), the INITIAL VALUES OF TRACERS is used by T2D. So my storred salinity distribution is lost for the new simulation. Whats the best way to keep the storred salinity distribution, while introducing a second tracer?

Many thanks, Peter

Hello,

On point 1: I agree with you, for example in function TR we see that the rank in the list of prescribed values (stored in array TRACER) is:
IRANK=ITRAC+(I-1)*NTRAC for boundary I, so the order is: all values of boundary 1, then all values of boundary 2, unless I am wrong somewhere. I'll check documentation.

On point 2: it should not be as you say. See subroutine rescue.f, only the tracers that have not been found are re-initialized. They are recognized by the tracer names declared. So if you really see that salinity is reset to 0, it is a problem somewhere, e.g. if the tracers names change (or if we have a bug somewhere, in which case I would need your files).

With best regards,

Jean-Michel Hervouet

Hi again,
Problem 2 is now fixed. I actually changed 'SALINITY' (first computation) to 'SALINITY kg/m3' (second computation), which T2D didn't recognise as the same variable. I have now changed back to the original name and the storred salinity distribution is resumed!
So all fixed, thank you!
Peter