Laurie Neilson

Hi,
Is there any way to project or show pathlines from a 3-D model onto a cross-sectional view?
Laurie

Hi,
I am modelling a 3D saturated (phreatic) multi-slice problem - groundwater flow only.
I want to apply a constant water flux across the top slice (recharge) of 175mm/y.
Can I simply apply this value (with the correct units) to each node (Type II BC), or do I need to adjust it somehow so that the flux is spatially constant at 175mm/y across the whole slice?  Does Feflow take the applied flux value at the node and multiply it by the area associated with that node to get an areal flux rate?  Is that why the results indicate different flux rates for each recharge node?
Also, if the top slice is providing a vertical recharge flux, can I assume that the flux will not be influenced by aquifer thickness in my 3D problem (i.e. I can leave the default setting for nonintegral boundary condition)? 

Laurie

Thanks Peter.
Another question.  I am using phreatic for the top slice and unspecified below.  The results look fine (I have flux out of the top slice where the seepage face should be, my velocity vectors look good and the head contours and water table are reasonable).  My problem is that the budget analyzer indicates I have too much water going in. 
I have set the specific options to unconfined, and the constraints are set to unconstrained as sseepage face if falling dry at bottom or reaching the op surface.  I have tried decreasing the tolerance and refining the grid but I still get the same imbalance.  Is this because my water table crosses many slices? and the slices are not allowed to go completely dry? (I am running saturated mode).
Can I determine how much water is flowing through the system by subtracting the imbalance from the inflow?
Any ideas?

Hi,
I am modelling a layered heterogeneous system in steep topography and thus the water table crosses multiple slices. 
The top slice is phreatic and underlying slices are unspecified. 
Is there a way to determine the resulting water table surface elevation?  (i.e. as it crosses the layers?).  Does the head in the top slice represent the water table surface?  Or does it represent the residual water table in that slice where it has gone "almost dry" and the water table is actually the head at the underlying slice?
Laurie

Thanks Peter,
I just wanted to make sure because in the Feflow Help it says "The layer covered by a fixed slice will always be considered as a confined layer".  Perhaps the wording could be changed there to say "considered as a saturated layer"?

Laurie

Hi,
If I assign a "fixed" slice below a "free and moveable" slice, does Feflow treat the top of the fixed slice as impermeable?  I want to fix the stratigraphy at a certain elevation but I also want vertical flow to be allowed from layer 1 to layer 2.
I am modelling a layered system, saturated, 3D, unconfined. 

Laurie

Hi,
I think my question fits here.
I am modelling a simple seepage face in the side of a hillslope (simple rectangle problem).  I have unspecified (i.e. default no-flow) boundaries in the upslope and lateral boundaries, constant head at the downgradient boundary.  Top slice is free and moveable and has a specified flux with a ground surface constraint.  The model is working well, except I get some groundwater mounding in the area of groundwater recharge, which I think is causing my water balance to show a net inflow.  Any suggestions ?     
Laurie

OK, thanks.
That helps! :)

Hi,
I am having trouble understanding why my boundaries that are set to "no-flow" (2nd type) have flux showing in the budget analyzer and fluid flux analyzer.  Should they not have zero flux?

Laurie

Hi there,
I am doing simulations to show the development of a hillslope seepage face due to precipitation infiltration.  I have started with a very simple 3D domain with 1 layer.  The top surface is set to free and movable (unconfined). I am running transient simulations and saturated flow.
I have applied no flow boundaries at all lateral boundaries and at the bottom slice.
I have applied a flux (type 2) boundary for the top slice and then constrained it when the elevation of water table (head) exceeds the ground surface (imported from a database).  - to allow water to exit at the seepage face.

I have a few Questions:
1:  Confirm that I do not need to actually use the “seepage face” boundary condition for this type of 3D model.  The specified flux boundary at the top slice seems like a better approach.
2. Confirm that I do not need to use inflo/outflow on top/bottom in “materials” to specify precipitation recharge.
3.  My results look OK, but after running for 10000 days I still have a net loss of water from the system.  I assume that if I run for long enough the water budget will be balanced?
4. Can I visualize the streamlines somehow in halt and view results mode?  I would like to do this through a vertical slice.

that's all for now, Laurie