Unstable dam break model with variation of manning

[Romero]

Hi everyone,

I have 24 km extension model with and i want to compare the influence of manning in a dam break simulation. The model runs stable with manning 0.02 and 0.015, but if i alterate them to 0.18 and 0.0135, the model goes unstable, and i can not perform the analisys of variation of manning in a dam break scenario.

Anyone knows why the model runs unstable if i just altarate the manning? Or if there is some method i can adopt to run the model with another manning without the model keep unstable?

Thanks

[Chris G.]

Your model is not robust enough to take a wide range of n values. I’d say an n value of 0.0135 is way too low, anyway. Even if on concrete, a dam break flood wave will be very turbulent with a lot of debris-higher n values are warrented. Try very high n values. Get the model stable. Then slowly lower the n values, running the model between each change. When the model crashes, find and correct the source of the error, then continue on lowering your n value.

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