how to solve instability problem in hec-ras 2D

[mab aba]

Hi, I’m modeling a dam using HEC-RAS 2D, and I have instability issues with a high iteration number (more than 500000 itereation) in the dam area. I tried to reduce time step and refine the mesh but I didn’t improve so much the results. which parameter that I should modify to reduce instability in this kind of situation like dam where the rapid flow changes?

thank you

[Eric R]

Sometimes, reducing the mesh excessively makes the solution even more unstable. Try increasing the dimensions of local cells.

[Chris Goodell]

I agree with Eric. Also, increase your weir stablity and decay exponents to 3 (computation options and tolerance window).

[Author]

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