Bottom flux when lower boundary condition is variable pressure head BC

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OULIGEI
Posts: 2
Joined: Mon Nov 16, 2020 10:56 am
Location: China

Bottom flux when lower boundary condition is variable pressure head BC

Post by OULIGEI » Wed Mar 31, 2021 2:50 pm

Dear all,
To study the flux into/out the model;Firstly,I use hydrus-1d build a model,the upper boundary condition is atmosphere BC with surface layer( from field data); the lower boundary condition is variable pressure head BC( from field data);initial condition is water content (from field data);I run this model and get the bottom flux
Secondly,I change the model lower boundary condition BC,let it become variable flux BC(the value is from the first model bottom flux) ;I run this model and get pressure head,but it is not same as the pressure head in the first,my question is:what is the bottom flux in variable pressure head BC?does it represent groundwater into/out the model?
regards,
ouligei

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

Re: Bottom flux when lower boundary condition is variable pressure head BC

Post by Jirka » Wed Mar 31, 2021 4:30 pm

Yes, it does. However, it is likely quite variable with time. Whenever you changed the bottom pressure, you will get a large inflow or outflow as the system reacts to this change. You would likely need to describe this detailed dynamics to get similar results with head or flux bottom BC. J.

OULIGEI
Posts: 2
Joined: Mon Nov 16, 2020 10:56 am
Location: China

Re: Bottom flux when lower boundary condition is variable pressure head BC

Post by OULIGEI » Thu Apr 01, 2021 2:33 am

very thankful!I understand what you mean,I will change the data numbers and try it again :D

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