open TELEMAC-MASCARET The mathematically superior suite of solvers

In my case study, there is many negative water depth in my domain.

I already used:

TREATMENT OF NEGATIVE DEPTHS = 2

CONTINUITY CORRECTION = YES

H CLIPPING = YES

MINIMUM VALUE OF DEPTH = 0.00001

But the negative water depth still appeared in my simulation.

Does anyone know the reseason and the solution?

Thanks a lot

Best wishes,
Qiang MA
2014-3-9

Hello,

You can check if it works with:

TREATMENT OF LINEAR SYSTEM : 2

but it is probably not the reason.

H CLIPPING = YES is not necessary and should be removed (it may spoil mass conservation). However it is strange that with this option you have negative depths.

You should also check your initial conditions or the previous computation file if it is a computation continued.

This is what I can say for the moment, but I see no obvious reason so far,

Regards,

Jean-Michel Hervouet

Thank you very much.

I will try your suggestion, and let you know it works or not.

Best wishes,
Qiang MA
2014-3-10

Dear Jean-Michel:

Firstly, I removed the Keywords "H clipping = Yes " as you said maybe there is some mass balance problems. And I input the keywords of "TREATMENT OF THE LINEAR SYSTEM = 2", but the negative water depth still there.

Secondly, my initial condition is 0.002m and my "MINIMUM VALUE OF DEPTH" is equal to 0.00001m. It worked before which gave me the minimum value of water depth equal to 0.00001m in the simulation results. But now it doesn't work, I don't know why

My results is here, the minimum water depth is still negative...




And this is my cas file :




I don't know how to solve this problem, seems there is some insteability problems in my model.

Thanks a lot

Best wishes,
Qiang MA
2014-3-10

Hello,

Can you try to add the following keyword with this value: MASS-LUMPING ON H = 1.
It is recommended such a value in the TELEMAC-3D user manual.

Hope this helps,

Chi-Tuan

I will try that.

Thanks a lot.

Best wishes,
Qiang MA
2014-3-10

I input the keywords as you told me "MASS-LUMPING ON H = 1"

the negative water depth was decreased, but still in my simulation results.

Best wishes,
Qiang MA
2014-3-10