• Representing drains

    I am having difficulty with representing drains/interception trenches in my model.

    I am using a third-type boundary condition, h at the drain nodes is set to z, the node elevations, and a minimum constraint h_min set also to z, the node elevations. The maximum constraint is not set (+ INF). Assigning the BC and the contraint is done by joining to a polygon representing the location of the drain. This assignment is made on adjacent slices (slices 9 & 10 of an 11 slice model). I have assigned the OUT transfer coefficient to be very high (for an ideal drain) and the IN tranfer coefficient set to zero. These transfer coefficients are assigned to each element within the polygon on all layers. The elements within the drain polygon are assigned a Kx=Ky=Kz of very high (for an ideal drain) on all slices. The mesh is very refined in the region surrounding the drain.

    My problem is, after the model is done and examine the results in the budget analyzer, I see that that during certain times (transient model) I have water moving from the drain into the domain approaching the same rate that water is leaving the domian into the drain. My expectation is that water should never flow into the model domain from the drains. When there is a preoblem with influx, the in-flowing nodes seem to be consistent, that is, the influx always seems to occur in the same locations.

    The purpose of the model is to detrmine the sustained flow rate into the drain so this precludes using type-4 well boundary conditions.

    What can I do to ensure that the drain never produces water?
  • Recharge budget errors??

    hi again,
    [color=purple]i had a problem with summing the rain recharge to my model.[/color]
    i followed the instructions of previous forum:
    see:  http://www.wasy.de/forum/index.php/topic,182.0.html
    i.e.: mesh centers recive recharge, IDW interpolation 1 neighbour. 
    afterwards, mesh inspector show "0 in/out flow on top" to elements outside the recharge zone. so far, all good.
    however, [color=purple]when i run the model i get recharge to elements which found next to a recharge zone (touch other elements whithin the recharge zone)!!!
    i'm using "budget analyzer" - "elements" - no snap.[/color]

    is it my error? some consideration of the FEFLOW? maybe software errors?

    ??
  • colors in 3D Options

    Hi!

    I'm trying to use the PATHLINE module in 3D OPTIONS

    I'm just wondering how to keep the color settings I had in the postprocessor?!?!?

    thank you!
  • Re: well condition: distributing flux according to transmissivity

    sorry!
    think I forgot to say thank you for your reply... I've read it a while ago now!
    thomas

  • Flow barriers

    What is the most appropriate way to represent flow barriers such as sheet-pile walls?

    I have constructed experimental models wherein I use a single row of low-K elements and a double-wide row of low-K elements. In both cases, these barriers are effective in diverting flow. However, in my model of a real site, I find that versions with single-row, low-K barriers allow particle tracks to pass through as if there was no barrier at all.

    Is there any plans to add the ability to create a no-flow boundary like the HFB package in MODFLOW?

    Dwaine
  • well condition: distributing flux according to transmissivity

    Hi everyone!

    I have a feflow model

    ->multi-layered
    ->3D heterogeneous K field
    ->pumping wells

    I'm using the 4th kind boundary condition for the wells, with well bore condition (specific option setting).

    I initially thought that I would enter a single value as a global pumping rate and that the flow rate would be distributed to the various layers on which the wells have been place with a flow rate proportional to the transmissivity of each layer of the model.

    I realized that I was wrong and entered the pumping for each layer as:

    (total pumping rate / n slices = slice pumping rate).

    This way, all of the slices have the same pumping rate... even tough it makes no sense in a heterogeneous K field setting...

    My question is : ''Do I have to calculate transmissivities by hand and enter the 4th conditions on each slice as a transmissivity related proportion of the whole pumping rate?''

    Or is there some built-in function?

    Any help or suggestions appreciated!!!

    Thanks!
    Thomas
  • Re: well with 2nd BC

    hi!
    by using the constrains of 2nd type boundary (Max=0) you design the boundary as outflow only,so you solve the "injecting" problem.
    transfer in/out will only goes with 3rd. type boundary. so that won't help you.
    consider changing the Kz of the well cell to infinite number so once water will enter the "well cell" they will be run quickly upward.
    good luck!

    Elad Dafny
  • Re: Lake on an island

    I looked at the cross section.
    1) why do you enter flux only to the  lower half of the boundary? and not to all the boundary (left and right)?
    2)to get a head which is about the topography on your island you need to enter lower K's in the island domain, so water level could be rise.  either do it by change the isotrophy 1:10 at the island domain.
    but you'll need a good excuse for that ...

    3)after you raise the levels, you can enter a lake. you can do it by head boundary on the surface of the lake.

    Good luck
    Elad
  • Junk topics in the General Forum

    Can anything be done to remove/filter/or block the spam posts in the General Forum?
  • Re: who can help me!

    for first aid-
    did you use the constrains?
    for "flux" inflow only boundary mark the "Min" checkbox and input 0 to the box near it.