3rd type boundary conditions

Hi,

I assigned zero to the Transfer Rate In, but the Budget Analyzer still showed that flux in through 3rd type boundary conditions is much larger than 0 (like 400cubic meter per day). Why is that? Thanks a lot in advance for your reply.

Zheng

1) how much does 400 m3 makes in % of your total budget?
if it is just a small percent you can ignore it!
2) when you set the 3rd. kind boundary you can constrain the in and out flux.
    maybe you haven't done that?

all the best,
Elad Dafny

I am having the same issue as above.

Cauchy boundary inflow rates are large and do not change with in-transfer rate.  Even when it is set to zero.  How do I scale the stream conductivity (in this direction)?? I used the constraint method.. but this is undesirable. I still want to have inflow from streams, but just need to scale the magnitude somehow.

Thanks in advance for your reply.

Blair.

Hi,

I had also some case where setting a Transfer Rate to 0 does not restrict the flux to 0. I think this is because of some small numerical errors. Also you have to keep in mind, that you have to assign this value to all surrounding elements, which may cause some problems with neighboutingnodes.

I also would prefere the constrain method.

To my experiences the flux constrains do work quiet well for transient models. There maybe some problems in steady state model runs. The constrains are not checked every iteration. You should (maybe several times) rerun the model and check the water balance.

Zebra

Hi,

I am also having a similar problem (see pictures attached)

I have set different 3r kind BC (Cauchy) in a 3D model (on the top slice and with all the nodes in the river's vicinity selected). All the condition are suposed to be an exit of the model for the water: so the in-transfer rate is set equal to 0, and the out transfer is set to a positive value.

What I find in the rate budget is that there is a very high value for both in and out rate on the Cauchy BCs bar. The difference between these values is sometimes an exit rate that I could interpret as the real water leaving the model in that area, but many other times it just doesn't make any sense... I really need to understand how much water is leaving the model to validate it.

Also, by checking the head distribution it doesn't seem that there is any place where the water is entering the model through the BC.

Thank you very much,

Guillem

From only looking at the images it is hard to tell what is going on. I'd recommend that as a next step you plot the rate budget on all the transfer nodes to see where the inflow occurs.