open TELEMAC-MASCARET The mathematically superior suite of solvers

Hi guys
I am using Telemac3d to model the particles in a stormwater basin.
my basin is made of concrete and I don't expect erosion for its bed.
but the result says that:
TOTAL ERODED MASS : 34.8909570
and this value increases by the time as we have constant flow.

Could you please tell me how can I stop this erosion of bed?

Thank you
Ruli

to be more specific
I think I need to set the BED LAYERS THICKNESS to zero but I can't find the keyword or proper code.



INITIAL MASS OF SEDIMENT BED : 14249999.999997508

but as I said I don't need this, how can I set it to zero...?
Thanks

Hi Ruli,

There are the keywords "INITIAL THICKNESS OF SEDIMENT LAYERS" and "BED LAYERS THICKNESS" but I think it's not the good solution.

If you want to initialize your whole domain with no sediment at the bottom, the easiest way is to modify the subroutine noerod.f, so as to set ZR=ZF (ZR: non erodible bottom elevation, ZF: bottom elevation).

I hope it helps,

Regards,
Laurent

Thanks for the help.
through stting ZR=RF I got rid of that default sedminet layer.

But now I am facing weird rsults.
I defined two phases for my simulation.

1st phase:
PRESCRIBED FLOWRATES =-0.3;0.3
INITIAL VALUES OF TRACERS = 0.001
PRESCRIBED TRACERS VALUES = 0.0 ; 0.001

2nd phase:
PRESCRIBED FLOWRATES =-0.3;0.3
INITIAL VALUES OF TRACERS = 0.0
PRESCRIBED TRACERS VALUES = 0.0 ; 0.0

I can see in BLUEKENEUE that in the second phase I have the deposited mass on the bed which is more than the first phase (obviously as the second phase is computed from first phase).

So I should expect having more deposited mass at the end of second phase simulation. But in output file it is not like that and again as I put ZR=ZF, INITIAL MASS OF SEDIMENT BED : 0.000 and in this output file the deposited mass is not summed with the previous phase.

How can I fix that?
Thanks

Hi Ruli,

I'm not sure too really understand what you mean. If in BK, you see in your results file that the deposit is higher at the end of the second phase than at the end of the first phase, what is the problem?
I guess that when you speak about the output file, you mean the log file. If yes, the INITIAL MASS OF SEDIMENT BED only accounts for the initial conditions and it's normal that is 0, you should look at the mass balance at the end of your simulation instead.

If I missed something in your explanations, please clarify or give more details by providing the log file. Also how do you make the transition between the 2 phases?

I hope it helps.

Regards,
Laurent

Yup, by output file I meant log file.
even in final mass balance, for the second phase, the amount of sediment mass is almost the same as first phase which does not make sense. As you said it should be higher, but it aint.

In addition, I think I have a problem with this keyword: PRESCRIBED TRACERS VALUE,because I also don't see the paticles coming in through the inflow (in BLUEKENUE) and all I see is from INITIAL VALUES OF TRACERS.

for transition of phases, I used COMPUTATION CONTINUED keyword. if I understood what u asked.

I actually want to have constant concentration in my inflow for the whole time of simulation and see how would be the sedimentation for these particles and how much retain in the basin, etc.

Should I use this keyword: VALUE OF THE TRACERS AT THE SOURCES ? if yes how can I achieve the above mentioned goals.
Thank u

I don't understand why you're doing 2 phases, one should be enough.
But your log files seem to be normal. At the end of your first simulation, it seems that you have a deposition of 0.9494420E-02 (MASS LEAVING THE DOMAIN, not in suspension). When you do your restart, I think this previous deposition is not reused (as you provide the same noerod.f subroutine). You can check it by looking at the deposit results of the first time step of your 2nd simulation.
No need to introduce "VALUE OF THE TRACERS AT THE SOURCES" as you don't have any source in your model.


Other remarks:
There is no water flow in your domain, you're just computing the ambient sediment deposit from zero flow. Is it what you want ?
You didn't provide the sediment properties in your steering file: settling velocity, critical erosion/deposition shear stresses.
It's normal that your sediment concentration decreases, as the particles settle on the bottom during the simulation and there is no input by the boundary.

I hope it helps.

Regards,
Laurent

Sorry it seems that I uploaded wrong files. I will upload those with water flow soon. in that simulation, although I have defined the prescribed water flow and prescribed tracer value, I don't see the particles coming in to my basin through the flow. I will upload the file as soon as I get to my working computer.

However, even in this simulation I do not see the deposited sediment on the bed in BLUEKENUE, why ?

Thanks for your help

Now I will make my question simple:

I am going to use now only one phase for this question. Why I don't see the sediment in output or BLUEKNEUE?
before adding other properties to steering file I want to see the particles coming in with my inflow.





Thanks for your support