open TELEMAC-MASCARET The mathematically superior suite of solvers

Dear all,

In order to simulate deltaïc environment (coupling of telemac-2d, sisyphe and tomawac) I need to program a hotstart to help convergence at inlet boundary. However, I encounter difficulties to re-use the result of the previous simulation. Indeed, despite the hotstart, I encounter free velocity problem and don't really understand how to fix them (NB : Froude number is below one so I'm in Fluvial regime). First, I need to specify that I have a difference of elevation between the inlet boundary (385.6 m) and Lake Geneva (372.10m) at outllet of the domain is about 13.5m. Thus I tried difference strategies :

• First to prescribe an initial elevation of 385.6m to fill the domain and let stabilize during a high period. Concerning hydraulics despite the convergence period and the small required timestep there are no problem but when coupling to sisyphe, there are lots of erosion and deposition outside of the river. It creates very high computation costs when coupling telemac to tomawac.
• Secondly, I tried to dig a hole in bathymetry at inlet, it was also a nice solution to help convergence of telemac-2d but it creates a huge trap for the sediments that deposited just at the inlet boundary.
• Third, I tried the hotstart with the real topography (without the hole mentionned above) and I didn't manage to help convergence. That's why I ask for your help.

If you think the solution to my problem is not the hotstart or if you have advices please let me know and I will try also these solutions.
You will find attached to this message my .cas file for the hotstart, and the necessary file to compile it.I Hope it will help you to understand where my problem is.

With best regards,
Alexandre

Please find attached here the link to download the previous computation file :

www.grosfichiers.com/d45qffxnsAe

Best regards,
Alexandre

Hi all,

Reading my post again, I think I was unclear in my message.


Here is the geometry file with the hole in the bathymetry :




Here is the geometry file without the hole on the bathymetry :



And you must adapt the following file to run the simulation with hotstart with and without the hole (with the geometry file with the hole in the bathymetry it runs but with no hole in the bathymetry the hotstart is not running - SUPERCRITICAL ENTRY WITH FREE DEPTH problem) :




Hope it is more clear like this,
Alexandre

Dear all,

Problem solved, it was numerical parameters that were'nt correctly set.
I uploaded hereunder the .cas file that works in case someone encounter the same problem with a steep bottom geometry :





Hope the .cas file will help, do not hesitate to contact me if you encountered similar problem and do not understand how to solve them.

Best regards,
Alexandre