Denim Umeshkumar Anajwala

Hi Guiseppe,

This sometimes happens in case of a relatively large abstraction for a single well. You probably see an overshoot of head values at the nodes around the well nodes - on regional scale then everything is OK again. The reason for this is in the default handling of storage, that involves the neighboring nodes. To fulfill the required steep gradient towards the extraction nodes, the solution then generates a higher water level at the surrounding nodes. You can try to switch to 'Lumped Mass' on the 'Numerical Parameters' page of the 'Problem Settings' dialog to overcome the problem.

Good luck!
Peter

... and then just use  'Save as' and choose .fem as the format.

The latest version FEFLOW 6.2 will tell you. In general, the flow simulation in most cases leads to a symmetric equation system, the transport simulation to a nonsymmetric one. There are exceptions, though, e.g., depending on the solution scheme unsaturated flow may lead to a nonsymmetric flow equation system.

Hi Mark,

The bottleneck is clearly the overseas connection in your case. The server is hosted in a server farm that is directly connected to an internet backbone, so that there should be no relevant limit on the server side. There are currently no mirrors. And you are right - the 'Patches' are indeed full downloads at the moment. There were some technical reasons a couple of years ago that made us switch to this solution (we had small patches before). We will, however, as soon as possible (I don't want to promise anything regarding timing here and now) have a look into it to see whether the problems of back then have been overcome.

It would be good to know if others are facing the same problems.

Best regards,
Peter

Recharge is in the unit [L/T] (or - equivalent - [L³/(TL²)]), representing a volume of water per time and area. Thus you can basically use the same values, no matter what the element size is.

Indeed I'd also typically use slices 1 and 2. In case of a thick top aquifer, it might be worth putting an extra slice at approximately the depth of the river bed. You should be aware, however, that your model assumes that the location of the river is a perfect groundwater divide in this case - which might or might not be true.

Hi there,

I have a question understanding the modeling of a river. Let's say we have a river as an outer model boundary in a 3d-model with ten layers, all slices are horizontally constant. So for example the rightern model boundary is the river. River bed in reality would be located within the second layer of the model area. Top sliced is phreatic, model is unconfined. I would like to connect the river with the aquifer via fluid transfer bc. with constraint (head = river bed). To make it simple, let's say river bed and even the head in the river is constant within the model area.

--> So do I use the fluid transfer bc on all slices? Or just on slice 1 and 2? Or in general, all slices from top slice to the river bed, but not below??

I guess I shouldn't use the bc on all slices, coz results show an outflow from my model below the river bed (below layer 2, where the river bed is located) in that case. I expected a vertical flow towards the river in the lower layers, and not a horizontal model outflow in those layers.

The flowfield in cross-section corresponds to my expectation, if I use the bc only on slice 1+2.

Could someone please confirm?
Thanks a lot....
h.

There are different options that may lead to the model showing no significant reaction to a variation of the BC values. For the river, the main factor besides the transfer rates is the drain-/fillable porosity. If this is large, the aquifer has more ability to buffer water level changes in the river. Are you sure that the system is perfectly phreatic? If there is one (or several) low-permeable layers (e.g., thin clay layers) on top or within the otherwise phreatic aquifer, the system may in reality be (at least partly) confined, leading to the fast reaction on river levels.

As an alternative to re-doing the entire mesh generation (in case your model would require a lot of data input to be done again in this case), you can manually refine the mesh around the new well location and use the move and smooth options to ensure both perfect positioning of the well and good mesh quality. All these tools are located in the Mesh Geometry toolbar.

In case you apply an automatic time-stepping procedure, it will make sure that all the time stages in the time series will be considered as time steps. This means that no time step will be larger than 10 minutes, possibly leading to long simulation times. Inputting water levels on a 10-minute interval will thus also ensure that you'll get output every 10 minutes.