computationalgeography / lue

LUE Scientific Database and Environmental Modelling Framework
https://lue.computationalgeography.org
MIT License
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Finetune `kinematice_wave` #703

Open kordejong opened 3 months ago

kordejong commented 3 months ago
saeb-faraji-gargari commented 3 months ago

-Just as an idea, the Newton-Raphson method may diverge when lateral_inflow is negative. In this case, I would suggest using discharge_guess as new_discharge (new_discharge = discharge_guess;) since discharge_guess is the solution to the linear discretized version of the kinematic-wave equations.

-The following criterion needs to be satisfied for the convergence of the Newton-Raphson method: | fq * d2fq| < |dfq|^2

Ref: https://math.stackexchange.com/questions/3136446/condition-for-convergence-of-newton-raphson-method

When lateral_inflow < 0, − _known_terms (-C in Chow's book) becomes positive, may lead to a large positive value for fq. This can violate the convergence criteria of the Newton-Raphson method. This issue can be considered in the future to improve the kinematic-wave operator.