Question about variable flux BC.

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Estrella
Posts: 2
Joined: Sat Oct 10, 2020 3:50 am
Location: China

Question about variable flux BC.

Post by Estrella » Mon Apr 05, 2021 5:49 am

Dear Prof. Jirka,
I used both variable flux BC and atmospheric BC to model the evaprotion process (no rainfall, ponding and runoff) which have the same results (observation pressure head, vtop, htop). HcritA has same impact on both of these BCs.
Does it mean that the variable flux BC under only evaporation situation is also a system-dependent BC? And I did not find the specific solution in the Code (I only find htop = HcritA in AtmBC, but I did not understand which code make the htop = HcritA in variable flux BC), could give me some advice?

Thank you very much!

Estrella.

Jirka
Posts: 5216
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

Re: Question about variable flux BC.

Post by Jirka » Mon Apr 05, 2021 4:18 pm

The code treats the time-variable flux upper BC the same as the atmospheric BC when a positive flux is specified (since the only other alternative would be that the code would have to crash for the lack of water in the profile to satisfy the specified flux). However, for a negative flux, the code will try to satisfy this flux (by increasing the surface pressure heads, even if those values may become unrealistic), and it may eventually crash. It is up to the users to use only reasonable values. J.

Estrella
Posts: 2
Joined: Sat Oct 10, 2020 3:50 am
Location: China

Re: Question about variable flux BC.

Post by Estrella » Tue Apr 06, 2021 5:14 am

Thank you very much! :D

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