Phreatic Mode

Hi,

i´m modelling a 3D heat transport model with unconfined conditions. There are 7 layers for the partially saturated zone, saturated zone and aquitard. I use the phreatic mode for calculation of recharge and heat transport in the unsaturated area. The boundary condition of the atmosphearic boundary is a time series of the ground top temperatures.
I switched the first slice to phreatic and the rest of the slices get the unspecified declaration. The slices with full saturation over the whole simulation time are fixed.
But there´s the possibilty to set all unspecified slices to even phreatic.
The user manual says that all unspecified slices are declared by the first slice above that is specified.

Why there are different results in time series of temperatures of the first combination and a version with all unspecified set to phreatic?
Thanks for responses.

Falk

Falk,
If setting all slices to 'Phreatic', FEFLOW will consider the storage parameter drain-fillable porosity in ALL these layers, not only in the one the water table is currently in. Therefore this solution is definitely wrong. The reason the setting can be done in this way is that FEFLOW - with some restrictions - also supports setups like this:
- phreatic
- fixed
- phreatic
- fixed
This would respresent a system with two phreatic surfaces in layer 1 and 3, with a fully saturated aquitard in between. Practically, however, in such cases a fully unsaturated solution might be the better choice.

Peter