Björn Kaiser

You can rotate your model by using the Autopilot Panel. The Autopilot Panel enables you to setup and export an animation for the active view window based on a keyframe concept. Four different categories are provided: [b]Simulation Time, Position, Clipping and Visibility[/b] which can be set up along a common presentation time line.

Here is a short example for the Position category: Set a first keyframe of [b]Position A[/b] at time [b]t=0[/b] and a set a second keyframe of [b]Position B[/b] at time [b]t=1[/b]. The resulting animation rotates the model from [b]Position A[/b] to [b]Position B[/b] between time [b]t=0[/b] and time [b]t=1[/b] along the presentation time line.

If you are interested in representing the detailed impact of groundwater abstraction on the river flow dynamics you probably need to couple FEFLOW with external open surface water hydraulic simulators

An interface between FEFLOW and MIKE 11 exists. The interface has been developed within the framework of the FEFLOW InterFaceManager (IFM): http://feflow.info/fileadmin/FEFLOW/content_tagung/TagungsCD/papers/29.pdf. MIKE 11 is capable to solve different approximations of the Saint Venant Equations.

Alternatively, you could use FEFLOW as a standalone simulator. Instead of coupling FEFLOW with an external code you could use a Fluid-Transfer BC within the FEFLOW model. A Fluid-Transfer BC applies a pre-defined reference head combined with a conductance parameter (transfer-rate as accessible as a material property in the Data Panel). This BC is often used for the representation of rivers. If there is a strong interaction between the river and the groundwater you could adjust the transfer-rate accordingly.

Depending on the spatial discretization you probably need to insert more slices/layers. The sketch roughly shows the framework.

Yes, you could use thin layers. Below please find a sketch which schematically illustrates a cross-section. Black lines indicate the input model, blue lines represent “dummy-slices” to model the foundation and the red line is the foundation.

BTW: These dummy-slices are not required anymore with the upcoming FEFLOW 7.0 release. FEFLOW 7.0 will provide the capability to use fully unstructured meshes (e.g. elements of type tetrahedra)

Seepage face Boundary Conditions (h=z and max flow-rate constraint) combined with a steady-state representation of the system needs to be considered with caution. Configurations where the water level h swings around z may trigger in ambiguous constrain activation or constrain deactivation. This situation intensifies if (even small) numerical oscillations are also present.

Accordingly, I recommend switching to a quasi-steady approach by adopting time-constant boundary conditions and time-constant material properties. In this manner, you enable the system more degree of freedom to evolve “through time”. In a steady-state mode you only have one step which may result in a wrong decision on whether or not the constraints are activated. If you switch to a quasi-steady approach FEFLOW has more (time)-steps for the decision and fluctuations may disappear.

To switch the setting please go to the Problem Settings and switch to Problem Class – Transient.
Run the model over a certain period and until a steady-state a solution is reached. If the solution between two different time steps do not change and if the capture and release from the storage is close to zero you may consider the solution as steady-state.

Short correction: A list about bugfixes is still published, but the link is not working at the moment. In the meanwhile, please find the list here: http://feflow.info/html/bugls_62.pdf

Is the vertical discretization fine enough? I suggest to introduce some slices in the “pseudo”-unsaturated zone. Go to the 3D Layer Configurator. If you choose an unrealistic high Distance (999999 m) FEFLOW will distribute all inserted slices equidistantly with respect to the elevations of the upper and of the lower slice.

You could also try to increase the residual water depth for unconfined layers in the Problem Settings – Free Surface as long as the imposed value fits to the hydrogeological architecture.

I guess, after you simulated your model you immediately inspected computational findings without opening a result-file with the extension *.dac. Indeed, FEFLOW allows to look on the results calculated at the last time step only if you go this way. I suggest another workflow. You may write simulated results in a dac-file by pressing on the Record-button in the Simulation toolbar before you start your simulation. When you want to postprocess your data, open the dac-file and browse through the time-steps.

There isn't just one way of doing it.

Apart from exporting to Excel as suggested by Pete you could also export the process variables (e.g. temperatures) as a shapefile and make field calculations using GIS. In addition, the FEFLOW Support provides a plugin, which calculates the minimum, the maximum and the mean temperature after each time-step of a transient model.

If you are interested please contact the FEFLOW support: http://www.mikepoweredbydhi.com/support.

I suggest to update to the latest Patch 9. Patch 9 covers some improvements with respect to the time-stepping. You could also try to adjust some settings in the model (e.g. mesh improvement, applying the fully implicit FE/BE predictor corrector scheme).