Posted Tue, 27 Mar 2007 08:10:30 GMT by Boris

I have some questions concerning the unconfined properties.

In which case do we use the free&movable or the phreatic options ?

As the phreatic option is considering, depending on the hydraulic heads, a unsaturated zone, can we use this option instead the unsaturated one ?
In other words, if we know that the aquifer water table is 10m deep for instance, and that we ignore everything about the unsaturated zone, can we use the unconfined phreatic option.

What are the limits (hydrogeologic cases) that we should not use it ?

I would like to simulate heat transport, with surface temperature boundaries and top infiltrations, is this option (phreatic) usable ?

Thanks for the responses

Posted Tue, 27 Mar 2007 09:52:19 GMT by Boris Lyssenko

the main difference between free&movable and phreatic is that in the 'phreatic' case the unsaturated zone is considered with a simplified linear approach. For your heat model that might be required because you'd probably like to consider heat conduction from the surface to groundwater via the unsaturated zone.
Phreatic might be less stable in some conditions because the linear reduction of conductivity for the unsaturated zone leads to very high conductivity contrasts in case of dry cells. In contrast to that, the parameter mapping in free&movable might lead to parameter interpolations in case of steep water tables.
So both options have their advantages and disadvantages and there's no general rule.

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