Martin Stewart

Hi,

i'm having some trouble getting a stable solution for an open-pit slope. I am trying to get a simple 3D model to mimic flow to an inclined pit wall with constant head boundaries to input flow from outside the model and seepage faces at pit bench toes on different slices at different bench elevations.  this works well except when i try to add recharge to the upper slice (in/out flow on upper slice).  the free space of the mined out zone is represented by high conductivities and low drainable porosity to try to get the water down to the top of the pit benches to recharge the bedrock.  I've tried setting the upper surface to free and moveable  as well as phreatic, but neither solution will converge in steady state.

Am I using a reasonable strategy or does anyone have an alternative?

Martin

I noticed in a model I am working on that if I have a boundary condition that is supposed to change at a specific date, it can change early.  For example, I enter a time varying function where head goes from 1400 to 1100m at 100 days using a constant curve function.  When I run the model to 99.999 days I find that the change in head is already included at some point in the latter stages of the transient run (not sure exactly when, sorry).  Is this a rounding error in feflow and if so what is the tolerance for error?  I need to be able to capture the moment when that boundary change is implemented so I can change timesteps accordingly to minimize instabilities with such extreme head changes.

Martin

Is it possible in FEFLOW to deactivated nodes/elements as you can in modflow?  I am modelling dewatering of steep mine pit faces that cut flat lying strata and am having trouble staying true to the oblique geometries. Does anyone have any good strategies out there for this type of situation?
Thanks,
Martin

Does anyone have experience/success using discrete feature elements in transient models? I am using an existing model which is stable in transient mode with complex arrays of multilevel wells and varying  boundary conditions. I am trying to add into the model vertical open boreholes which have been drilled to drain an upper perched aquifer through to a lower partially saturated one.

I have tried using discrete feature elements as single nodes connected vertically across several layers. I am using Darcy's law with a high conductivity (1 m/s) and a 1m2 cross section (they are BIG boreholes). My nodal spacing is a minimum of 1m and is tightly discretized around the discrete elements and I'm using extremely small timesteps to start, but the model is unstable. Any suggestions why it might be unstable? is there an alternate way I can model drainholes that will provide a stable transient solution?

(The instability is particularly apparent at the free and moveable upper surface which is also a seepage face boundary condition)


Thanks
Martin

Does using a free&moveable surface or a phreatic surface change the storage properties (Storativity/specific yield) of my model as cells change from saturated to unsaturated? Which material properties are varied in response to degrees of saturation for these two methods, do they both simply scale volume and conductivity directly by the saturation? What equations are used to calculate these relationships if not?

Thanks
Martin

Will the new version 6.0 (standard) support visual C++ GUI's?

Martin

Peter,

I missed that reference, thanks for pointing it out. Will the same batch file formats work for the new version 6.0 classic and standard?

Also there is a note I don't understand in the instructions, it states that "the -dac and -dar have to be used alternatively!". Does that mean I can't save consecutive .dac files for each .fem file in the batch?

Thanks again,
Martin

Is it possible to run an external module that can initiate FEFLOW, run a simulation then save the results? I would like to create a routine that is capable of running multiple .fem files in sequence. I don't think IFM can handle this, although please correct me if I am wrong. Anyone have any experience in this regard?

i would like to be able to run  a routine where I input a list of .fem files that are pre-configured, and let it run all the simulations in sequence automatically (so I don't have to come in continually over a weekend to save and start new model runs :P)

thanks
Martin

Hi,

I'm trying to put together my first IFM code and am looking for commands to ask FEFLOW to run a simulation and then save the results to a .dac file (starting the IFM code in +presimulation mode). It is a simple code that runs the simulation, loops back to automatically change parameters, then run itself again until all the parameter configurations have been exhausted (essentially a sensitivity analysis). Any suggestions from the programming crowd?

Thanks
Martin

I am a feflow 5.4 user. I see in my reference manual some very slick looking 3D diagrams showing pathlines as nice thick tubular paths in section 25 (e.g. figure 25.6 in "3d anisotropy and patterns of groundwater whirls"). Can someone tell me how to produce such diagrams, is it done in Feflow explorer or directly in Feflow?  I'm trying to improve on the presentation of my results.

Thanks
Martin