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Hello,
For the last couple of weeks, I have been struggling with an issue on my model. I use Telemac2D v8p3r1.
I observe oscillations on the time series of velocity and water elevation at low tide (see the second last peak in this figure: current_velocity.png image. Of note, oscillations during the first 24h are due to the model spinup).
After several tests, it appears that it is probably due to the presence of tidal flats near the area of interest. I tested different combinations of parameters to solve this, but without great success.
The lastest configuration is in the attached .cas file.
The cells have a size of 10 meters near the shoreline and in the studied area. Currents are high (3 - 4 m/s in the study zone). The purple dot is the point of extraction for the time series.
I wonder if there is a better way to handle the tidal flats?
Thank you,
Best
Nicolas

Hello Nicolas,

Have you tried to decrease your time step, e.g. 0.5 s rather than 1 s (or even less). Do you have smoother results for low tides then or the same as 1 s?

What about the output file/listing, do you have messages like:
POSITIVE DEPTHS SOLVED IN XXX ITERATIONS = MAXIMUM
INCREASE MAXIMUM NUMBER OF ITERATIONS FOR ADVECTION SCHEMES
?

If yes, and if it often occurs, you should increase the default value of the keyword MAXIMUM NUMBER OF ITERATIONS FOR ADVECTION SCHEMES (e.g. 100 or even more).

What you describe does not surprise me if the location where you look at time series is closed to shallows or in particular tidal flats or dry areas.
When it occurs, I try to draw figures at a location a little bit farther with deeper bottom elevations to avoid a kind of capping of the low levels (or disturbances).

I do not have more advice for your steering file at the moment.

Hope this helps,

Chi-Tuan

Hello Chi-Tuan

I have tried to decrease the time step, but the results are not smoother.

I don't have either any message concerning the number of iterations for advection schemes.

I will continue to work on it.

Thank you for your answer.

Nicolas