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Hello,

I run a 2D model using TPXO values as boundaries conditions.
With my first model which is quite small, everything works well. But with a second model much larger (500km of coastline and 300km offshore with depths reaching around 5000m), big oscillations of the sea level appears.
I add the following key words:
OPTION FOR LIQUID BOUNDARIES = 2
FREE SURFACE GRADIENT COMPATIBILITY = 0.5
Nothing changes.
When I put TREATMENT OF THE LINEAR SYSTEM = 2, the solution is quite good.
I don't understand why. Is someone can explain me why?
Thank you.

Hello,

The free surface gradient compatibility is meant for the pseudo-wave equation (TREATMENT OF THE LINEAR SYSTEM = 2), this is why it works when you add your last keyword. With the primitive equations (TREATMENT OF THE LINEAR SYSTEM = 1) you would have to resort to quasi-bubble element to prevent wiggles, but it is more expensive.

With best regards,

Jean-Michel Hervouet

Thank you Jean Michel.
Actually, I made a mistake using quasi bubble element.

Best regards,

Florence