• Connect BHE arrays with one another

    Hello there,

    I'm working on a model with a field of BHEs and trying out different flow patterns through the field. The options in the BHE connection editor are really good but it seems that there is one thing you can't do or I just can't figure it out. I want to have 2 or 3 "rings" of BHEs. First ring would be all the outer BHEs parallel, then connect the over all output of them to the input of the next ring of parallel BHEs and so on. Unfortunately it won't let me connect the output of one array to the input of another :(

    Am I doing something wrong or is it just not possible? Maybe a good idea for the next patch?
  • Re: Setting groundwater table to xx m below the surface

    Thanks a lot for the answers guys, your help is greatly appreciated :)
  • Re: Setting groundwater table to xx m below the surface

    Yes initial conditions primarily. When I set up the hydraulic head to -20 m for all nodes it looks fine. Except that the pressure above the water level is negativ when I set it up via hydraulic head IC. Is this negligible? Because when I change the pressure above manually to 0 it the hydraulic head looks like the pictures above.
  • Setting groundwater table to xx m below the surface


    I'm relatively new to FeFlow and I thought that this is an easy problem which I could solve after a bit of research but I can't figure it out. So what I'm trying to do is pretty simple, basically I just want the groundwater table of my 3D (8 layers each 25 m) model to be at 20 m below the surface. I've tried a couple of things to achieve this but none of them yielded the results I am looking for.

    First of all I went to Problem settings > Problem class > Free surface and chose 'unconfined aquifer' (unsure about constraint vs unconstraint head?). When I display the 'Pressure' of my model it transitions smoothly from 0 at the very top to 1961 kPa (200 m depth) at the very bottom. So far so good. Now for my purposes it should be 0 at 20 m depth and then 1765 kPa at 200 m depth. I know that pressure is just calculated from the hydraulic head input but I read in the tutorial files that you can use the pressure as input as well and FeFlow automatically calculates the corresponding hydraulic head. Sooo I went to the top slice and put 0 kPa, then to the second slice (25 m) and put 49 kPa because there would be a 5 m water column at 25 m depth and then finally to the bottom slice and put the 1765 kPa. Now that looked perfect when I displayed the pressure but once I switch to the hydraulic head view it's really messy (see attachment). This is the closest I got to what I'm looking for. How do I fix this?

    I used the hydraulic head IC and set it to 180 m at the bottom slice but then the pressure at the bottom is at 3726 kPa (=380 m water column) which is way too high. It would be nice to set it up in a way that I can just change the hydraulic head BC at the left/right borders a little bit to generate flow but to have the water table at 20 m below ground is more important.

    (Also what EXACTLY does the hydraulic head define? Say I set the hydraulic head for a node in 10 m depth to 5 m what does that mean? I understand it as 'There is the pressure of 5 m water column at this point' which would mean that the water table is at 5 m below surface at that point. Is this right? The tutorials don't really go into much detail.)

    There should be an easy solution to this and I hope someone can point me in the right direction.