open TELEMAC-MASCARET The mathematically superior suite of solvers

Dear Jean-Michel Hervouet,

Parallel to my previous posted work, I am working on prototype model as well by using Telemac 2D for now. I am facing some issues need your help as well. I attached pics showing the mesh, and boundaries. In my case, I have upstream inflow hydrograph, and I set the water surface elevation at the reservoir at 779.5 m ASL; however, defined the inlet liquid boundary is at an elevation 786 m ASL. In the subroutine CONDIN, I defined the water depth upstream of the dam is at 779.5m-ZF(I), so the distance between the inlet and the place where the water surface is starting probably dry. I would like to ask how to define water level between reservoir starting at upstream and tributary river that has know hydrograph? another issue is I dont have any information about the outlet except the bed elevation, I assumed the water depth is about 1m at the beginning. Is there any opinion? when I run, it gives me an error.

With Best Regards,
AMANJ

here is steering file

Hello,

In both cases of Telemac-2D and 3D, what is given to Sisyphe is the friction velocity.

Regarding your latest post, it is a common problem, you can try to give a special initial condition done with Blue Kenue. Starting from dry is also possible, but in this case you must think of boundary conditions and prescribe velocity and depth when the flow is supercritical.

Regards,

JMH

Hello dear Jean-Michel Hervouet,

I tried to run my model for more than 3 days and the result what I got is that when we activate the bed roughness predictor, it seems to me the Telemac 3D doesnt send data such as shear velocity or water depth to sisyphe and hence no sediment transport calculated; however, the model doesnt show any error when running. I dont know what was the reason but the overtopping flow occured and erosion is zero. here is the video about output 23 minutes duration of numerical run and the steering files. I hope this may help to figure out and help in solving this issue. I think the reason why the model is stabilized after the last time when we activate bed roughness predictor is that no sediment transport was calculated.



Thanks
AMANJ

log

Hi Amanj,

with the bed roughness predictor option Sisyphe calculates the Nikuradse roughness height according to your specified diameter 0.000245 m and sends it to Telemac-3D. However in your Telemac-3D steering file you specify TURBULENCE MODEL FOR THE BOTTOM =1. I can hardly imagine that you have a hydraulically smooth regime at the bottom, so I would adopt TURBULENCE MODEL FOR THE BOTTOM =2. Maybe this is also the reason why you have too low friction velocities. Be also aware that in Telemac-3D with a smooth wall specification the friction laws are not being accounted.

I'm a little bit pessimistic that the bed roughness predictor will solve the problems. We tried this option in reservoir flushing cases and it rather introduced instabilities than stability. But I'm curious.


Best regards,
Clemens

Hello dear Clemens,

I tried with option two, rough condition but it creates instability in the model. I dont know actually what will cause this instabilities but probably related to bed shear velocity or shear stress. In smooth case, hydrodynamic model is working well;however, the sediment transport doesnt work i means doesnt calculate bed evolution, but when change in to rough, it creates huge instabilities in both hydrodynamics and bed evolution.

Sincerely,
AMANJ

Hello,

I think the problem inc. solution which JMH mentioned in
#17248
could be a good approach. Actually this problem is shared by some of the available CFD+sediment transport models, like SSIIM.

Best regards,
Clemens