open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

I use the subroutine CORSTR to impose depth-dependent Chezy Coefficient in a 3D Telemac-3D model (coupled with SISYPHE). The purpose is to impose very small Chezy coefficient (4.9E-03) to dry nodes.





But I still got relatively large velocities (compare to the neighbors) at those dry nodes. So I got high sediment concentration at those nodes. Is there any method to fix this?

Thanks in advance!

Hello,

I looked at the shear stress and there's also very large shear stress in those red spots, actually at all the edges between dry and wet area. We guess that's because the limit of water depth (1.0E-03) is not zero at those dry areas. We're still trying to fix it.

Hello,

I don't think that what you are doing is correct, if you decrease the Chezy, it means that you increase the bed shear stress and there fore the concentrations;

The other thing which is rather strange to me is that you work in a coupled way (Telemac-3d and Sisyphe) so the bed shear stress should be directly calculated by the 3D model and sent to Sisyphe, so the corstr subroutine should not play any role...

What happens if you don't do anything?

Best regards, Cath

Thanks for your advice, Cath.

You're right. The high bed shear stress was caused by very small Chezy coefficient. I have a run in which I used constant Chezy coeffient 65. In this case the maximum value of bed shear stress is around 60N/m2. The "red spots" (nodes with high concentration) become less but still exist in the shallow area.



As far as I know, the subroutine CORSTR was called from telemac3d.f. Then arrays CF, RUGOF and UETCAR (U* squared) are transmitted to Sisyphe.

Best regards,
Qilong