Hello everyone,
For now, I am using FEFLOW version 7.4 to simulate groundwater flow to the drain, but I have a problem, so I try to build a box model and figure out this problem; please see the attached picture and help me.
I built a model with boundary conditions like the picture below.
And I want to assign the Cauchy boundary as a Drain boundary, so I assigned the In-transfer Rate = 0(1/s) and Out-transfer Rate = 99999 (1/s) to only let water flow from the aquifer to the boundary.
Although the In-transfer Rate assigned = 0, it still has the water flow from the boundary to the aquifer.
Please help me with this problem, I have tried many ways, but I figure out that the "Transfer Rate" does not care about "In-transfer Rate" or "Out-transfer Rate." How can I assign the Drain boundary condition for the model?
https://www.xmswiki.com/wiki/GMS:DRN_Package
[img width=200 height=150]https://i.imgur.com/n6Qb33I.jpg[/img]
[img width=200 height=150]https://i.imgur.com/9VyuDG8.jpg[/img]
[img width=200 height=150]https://i.imgur.com/68396TD.jpg[/img]
[img width=200 height=150]https://i.imgur.com/8wkLrGL.jpg[/img]

Thank you!
1) I see no point in using Cauchy boundary in this case. Since you are using infinitely high transfer rate, you can simply use fixed head boundary instead.
2) The easiest option to make boundary conditions one way is to impose flow rate constraint.

Flow rate constraint for fluid transfer BCs (option for fixed head BC is equivalent):

1) I see no point in using Cauchy boundary in this case. Since you are using infinitely high transfer rate, you can simply use fixed head boundary instead.
2) The easiest option to make boundary conditions one way is to impose flow rate constraint.

Flow rate constraint for fluid transfer BCs (option for fixed head BC is equivalent):