Removing discrete element flow from the model

Question regarding discrete elements. We are simulating a network of old mine galleries, that are draining the surrounding reservoir. To linke all together those galleries which are at different levels/slices, we use vertical elements. Upgradient the galleries outlet there is a flow that is consistent with the reality, however we can't find a way to remove that flow from the model, either with the source/sink editor of the DE parameters panel, or by linking the DE with one of the proposed BC. We would like to avoid using an IFM module if possible ...

Thanks, Didier

Hallo, I have the same problem. I tried linking the DE with a 3rd kind BC, but doesn't seem so elegant...

Since the date I wrote my post I can give some elements of reply:
- they aren't solutions to remove flow from DE except by linking them with a BC
- you may play with the arbitrary element to simulate plain pipes that are not directly linked to the aquifer except at the entrance and outlet of the pipe
- you should use a seepage face at the outlet of the pipe if you know the elevation of the outlet. Otherwise you can consider a flux, equal to your flow rate/pipe or gallery area, and watch for the quality of your piezometric contours around your outlet. You may see mounding or depressurisation if your flux BC is too low or high respectively.
- to use the 3rd type BC you have to assign In and Out flow rate in the DE parameter panels (I think).

It's just guess .... feel free to share your own ideas :) !
Didier

Try a 1st-kind BC with constraint set to allow only outflow; should work fine.

Pete

Hello,
I tryed both 1st and 3rd-kind BC; in this way I can quantify the discharge of the DE, but the flow still remains inside the system... in my case water flows from the confined aquifer into the unconfined above, instead of leaving the system as a spring...

Any suggestion?

Maybe try a specific flux BC at the outlet. If your DE has more flow than your BC, you will see water mounding around your outlet, because the model doesn't expediate all the flow that you want to. If your DE has less flow than your BC, you will see the inverse (the model has to extract more water than the flow from the DE, thus creating a drawdown cone around your outlet).

yes, I have that using a well BC, but it is very unconfortable, since I'm interested in monitoring the variable discharge of the spring under different scenarios...

Sure. The constrained flux will only help you to justify or correct your DE parameters. Once you reach a satisfaction, I believe you can switch it back to the estimated head, and simulated scenarios which affect your flux.
Cheers !
did

Francesca,  from your description it seems the flow is never sees the light of day.  Its not really a spring...?  If the flow is internal, your model should have a hydraulic connection between the two aquifers that is perhaps localized.  Perhaps discrete features or 3d elements that have large K. Check the flow between the two aquifers using the flux analyzer rather than the budget analyzer.  If it is a spring, you'll need to separate boundary conditions to simulate the discharge and the subsequent recharge.

Hi Pete! It is a real spring. Water comes from a deep confined aquifer, crosses the shallow aquifer with no interaction, and hopefully leaves the system.  I can obtain that in different manner, for istance putting a constrained constant head node exactly "above" the DE. It works, but I have continuosly to adjust the elevation of the BC, in order to catch the water from the deep aquifer spring and not to catch the water from the shallower! I also tried other solutions, but I have to respect other heat flux conditions...
I was just wondering if there was a cleaner way to achieve this result...

I see, Perhaps and additional layer or elements or localized zone of elements to help isolate the DE and BC from the shallower aquifer would help.