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Dear members,

I would like to ask about the duration of simulation using TELEMAC2D coupled with SISYPHE. The model has only
discharge and free bed evolution boundaries (in .cli file) since we doesn't have discharge measurements.
What would be the suggested duration of the simulation?. Please find attached a screenshot of the process, and also a reference screenshot of my bed evolution, essentially I need to know when those erosion and sedimentation
values will be stopped changing. Does I need to wait until the flux boundary 1 and 2 become equal?

Don't hesitate to request more details if you need or the model files by e-mail.

Thank you for your help!

Magaly

Hello Magaly,

The min. and max evolution is already very small (0.8E-6 / -0.2E-6). Depending of your aim of modeling this could be declared as zero evolution.

Nevertheless there is still an incoming bedload flux. Is it right that you have only one open boundary for the bedload? (only bedload flux 1) As long as there is an incoming bedload flux (and no outlet of bedload) I would expect (at least small) bed evolution changes inside the model.
Regards,
Rebekka

Dear Rebekka,

Thank you for your response,

I attached my .cli file. Actually i think i run the model with imposed boundary conditions (5)

Could you please give me some orientation just to run again, please?.

Regarding to the evolution, when i se that those values of evolution are smaller, it means that the model got equilibrium and i can stop it?

Dear Magaly,

according to your cli-file you have an inflow and an outflow for the hydrodynamic but only an inflow (equilibrium sediment discharge) for the sediment. This means you will have no bottom change at the inflow boundary and according to your hydrodynamic more or less sediment inflow. At the outflow boundary you should set a 4 for the type of boundary condition of the evolution in case the outflow boundary is open also for sediment.
Please see user manual section 2.7.3
5 4 4 0.0 0.0 0.0 0.0 40.0 0.0 0.0 ... 1


I don't understand your aim of study so it is hard to propose something. You wrote that you are looking for zero bottom changes. Do you want to have a constant discharge for the hydrodynamic? Is your model a river with one inflow and one outflow? Do you expect steady state for the hydrodynamics? Why do you expect that the bottom changes will decrease to zero?

Regards,
Rebekka

Dear Rebekka,

We are studying the hydrodynamics and sediment transport of a river bend. I am currently doing steady state simulations (one inflow discharge and and outflow boundary condition using a known water level).In regard to my question, i will follow your suggested change, however i don't know when the bed change must be in equilibrium (i suppose the changes never stop), because if i set any duration, i get changes at every print time in an increasing trend. Does it related to the "sum of evolutions" in the simulation (screenshot i attached in my post).

Thank you for your patience and time.

Magaly.