open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,
I need your support, please. Sisyphe and Telemac
I would like to simulate an open channel with a trapezoid profile. Focus is to simulate the Formation of the bottom surface in 'Sand dunes'. The channel is 1.4 m wide and 30 m long
Max. speed is ca. (0.9 m/s)
How small should be the element size,So that it simulates the change of the sole surface?

Is (1.00 mm) too small ? I know it depends on the time step too, but I can vary it. (Courant Number)

Thanks a lot
Rima

Dear Rima,
A model as the one implemented in Sisyphe, based on the solution of the Exner equation, is not suitable to simulation the formation of dunes. It can propagate a train of existing dunes, as perturbations in the bottom, but not to properly create them. Morphodynamics structures of a larger size, such as bars, are able to be reproduced and propagated by the Exner equations.
One thing to take in mind, is that your element size must be of a size able to well represent the bedform. A larger size, would lead to a "filtering" effect in your solution.

I hope it helps,

pablo