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Hello all,

I am a new Telemac2D user and I built up a part of an estuary (see Figure 1) with 2 WaterLevel boundaries.

In general the model runs and with "Thompson" the result especially the WaterLevel are mostly plausible (The course of the waterlevel and the peaks with "thompson" are ok). But as you can see in Figure 3 and 4 there are still some instabilities, noticeable by the oscillating of the waterlevel and velocity as well.

I have attaced the steering file!

Are there some more parameters which are helpful or has anyone any advices for me?

Thank you for any help

Best regards,

RunkleS

Hello,

These oscillations seem to be due to inf-sup condition, not to Thompson. You can try:

FREE SURFACE GRADIENT COMPATIBILITY : values lower than 0.9, down to 0.

You have also the keywords :

IMPLICITATION FOR DEPTH
IMPLICITATION FOR VELOCITY

which are set by default to 0.55, i.e. rather close to the stability limit of 0.5. You can try values from 0.55 to 1. (it may damp a little the results).

Otherwise H CLIPPING = YES should be removed, it is useless here.

With best regards,

Jean-Michel Hervouet

Thank you for answering so fast! I will try different options and let you know if I have new results!

The results are such better if I reduce the timesteps in general and in combination with IMPLICITATION FOR DEPTH, IMPLICITATION FOR VELOCITY.

Thank your for your advice!

With best regards,
RunkleS