open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

I'm working on a very narrow river and have a doubt about the accuracy I would get with a 2D telemac model of it.

The "river" is not more than 2 meter wide, its slope is around 1%. Its flood field is ~50 m wide, so 1D modelling would not work at all.

To correctly represent the main channel's topography in a 2D-model, the mesh should not be more than a few centimeters, and therefore the time step should not exceed a few hundredths of a second.

Do you think a 2D model is still indicated under those conditions ?

Hello Benoît,

I am doing something similar where the bottom width of my channel is 2.5 m wide. The mesh resolution is around 0.10-0.12 m and the time step is 0.05 s, which gives a maximum Courant number at the outlet just under 1 (but it is much lower across the domain) with my velocities. It seems to work fine, but it should be mentioned I am using T2D coupled with GAIA.

Hope this helps,

André Renault

Hello,

In addition to André's answer, TELEMAC-2D or 3D are used to model scale experiments. Not the most usual, but it can model such scales. Sometimes, some hard coded values or values of keywords have to be changed (in 3D in particular).

When using TELEMAC-2D, you should always think if the fundamental assumptions of Shallow Water Equations are OK:
- hydrostatic pressure,
- negligible vertical velocity and accelerations.

Hope this helps,

Chi-Tuan