Posted Thu, 04 Jun 2015 13:00:56 GMT by Hamdi Ashur
Dear everyone
Is it possible to simulate unsaturated zones if you use the Standard (Saturated) groundwater flow equation? My set-up is phreatic--> Confined --> Dependent. Even if I use “free” for the top slice, I still have hydraulic head in the top slice.

Furthermore, if I view the hydraulic head in a cross-section I see a potential line going from the top to the bottom, but the top consist of dry cells, so the potential line should first start after the dry cells (i.e. second layer). Is there any way to correct this?

I hope I explained my issues clearly, I appreciate any kind of help.

Best regards.
Posted Fri, 05 Jun 2015 13:56:23 GMT by Björn Kaiser
Yes, you can use the phreatic mode to simulate the unsaturated zone if you intend use the standard (saturated) groundwater flow equation. In a phreatic mode, the model stratigraphy is fixed and, as a consequence, elements may become dry or partially saturated. In contrast, to the unsaturated mode (Richards’ equation), the calculation of the unsaturated zone is simplified. Further detailed are provided by the FEFOW manual, page 51:

If you solve the groundwater flow equations you solve for the process variable hydraulic head on each node including the unsaturated zone. If you want to discriminate the unsaturated zone from the saturated zone in space, I suggest to use the zero isoline for the pressure (=0 KPa). The zero isoline for the pressure represents a visual replica for water table undulations.
Posted Sat, 06 Jun 2015 16:17:22 GMT by Hamdi Ashur
Thank you for the answer! Is there a way in Feflow to plot both the pressure and hydraulic head?

Best regards,
Posted Mon, 08 Jun 2015 07:02:42 GMT by Björn Kaiser
Yes, you can plot two or more process variables, boundary conditions and material properties. Right-click on the parameter of interest and choose [i]Lock Data View[/i] from the context menu.
Posted Wed, 10 Jun 2015 18:07:50 GMT by Hamdi Ashur
It worked perfectly. Thank you!

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