Björn Kaiser

Thanks Christian. I will check it.

Great Olivier, give it a try and please let me know if you have further questions.

Since the EP is solved as a process variable you have a remarkable degree of freedom to automatize the post-processing component of modelling. On top of that, you may intersect nodal EP's distributions as derived by multiple simulations you carry out with geological units by using boolean operators. That's a "nice" alternative to overlaying vertices of field lines over a fixed raster and calculating the frequency.

Thanks for the note Christian.

Yes, copying nodal or elemental properties from one FEFLOW instance to another FEFLOW instance by using the clipboard of the operating system is not possible. Alternatively, you can use the Quick import option or the Parameter Association as you already indicated. I will try to reproduce your observation. Could you please let me know which FEFLOW Update you are using? Could you please also let me know the number of mesh nodes?

Thanks Adam. Yes that's correct, if you call PostTimeStep the geometry will be updated.

The bug has been confirmed by the development which will be fixed with the next Update. Please let me know if you need a hotfix. In this context, the display update for geometry changes will only work in the callback PostTimeStep. This is intended to reduce overhead during the numerical simulations.

I did not test the fieldline (e.g. pathlines) computations in FEFLOW 5.3. But newer FEFLOW versions definitely support fieldline computations.

Thanks for the note, Adam. I was able to reproduce your observation. For me it seems to be a bug. I will let you know as soon as possible about any updates.

An automation to generate particle tracks is not possible with the current FEFLOW 7.0. This missing feature makes a PEST calibration impossible in case you want to use fieldlines.

As an alternative, I suggest to use Age-based simulations you can directly use in FEFLOW/FePEST. On top of that, age-based computations are more accurate in a physical sense than generic particle tracking techniques.

While standard streamlines are solely based on advection, other processes as such as diffusion and dispersion are simply neglected. Of course, Random Walk Particle Tracks (RWPT) mimic the additional effects diffusion and dispersion. However, both methods are based on a flow solution, because no advective-diffusive transport equation is taken into account. Moreover, these methods provide a visual inspection only. A quantitative evaluation can only be indirectly derived (second order).

Age-based computations provide a powerful alternative. Age computations do not only allow a visual inspection, but they also take budget quantities into account as driven by advection, dispersion and diffusion.

Let’s assume you are interested in delineating catchment zones. In this context you may work with the age-species Exit Propability (EP). You may prescribe Dirichlet BC’s for the EP (equal to 1.0) to nodes where water leaves the system (e.g. wells). A value of 1 at exit points corresponds to an exit probability of 100 %.

The EP is taken into account as a concentration, because internally FEFLOW solves a mass transport equation involving advection, dispersion and diffusion. During the computations FEFLOW reverses the flow field (vectors) in the advective terms of the transport equation. Accordingly, extraction wells become injection wells. These “injection wells” inject water with a “unit concentration” of 1 for the EP. This “concentration” is then transported within the porous medium and a plume may evolve. This plume can be used to delineate the capture zone.

The EP is available in FEFLOW as a process variable and in FePEST as an observation.

[b]For fluid flow, I was planning on using a well BC, with the pumping rate divided by 2*pi as recommended in the online help. However, the help says that in the case of axisymmetric models a specified flux boundary is preferred. What is the reason for this?[/b]

NeumannBC's are usually applied to have an "areal" inflow or outflow. The value for the assignment can be calculated according to the pumping rate Q, filter section B, radius R: q=Q/(2*pi*R*B).

[b]Could someone with experience modelling density-dependent flow provide some insight as to whether these BCs are best suited to this particular problem?[/b]
The selection of these boundary condition is not related with density-dependent flow. The principle is the same for non-density-dependent flow.

[b]And potentially comment on whether the divergence or convective form of the transport equation should be used?[/b]
If you solve the convective formulation of the transport equation and if you use NeumannBC’s or WellBC's for flow plus NeumannBC's/Nodal mass source sink for mass you specify only the dispersive transport component. The advective transport component remains unspecified. Accordingly, you cannot control the advective component and most likely you observe larger budgets to what you expected.

In contrast, if you apply the divergent form you specify all mass drivers (advective, dispersive, diffusive). As a result, calculated budget quantities will satisfy your expectations. The disadvantage of the divergent form is a more difficult handling at outflowing boundaries. Artificial accumulation of the concentration distribution may also occur in particular if the advective flow field is heterogeneous.

Each stored node selection in the Selection panel can be used as a separate budget group for which the calculated rate and period budget can be displayed as time series in the Rate Budget and Period Budget charts.

If you want to compare the Rate Budget chart with the budget shown in the Rate Budget Panel you need to use the same selection. The screenshot you provided from the Rate Budget Panel uses the selection [b]Tuneles Completos[/b]. I suggest, to show solely the budget of this selection in the Rate Budget chart. You can hide the other charts in the [b]Properties[/b] (right-click to open the context menu). The last value of the chart for the selection [b]Tuneles Completos[/b] must be the same as the value you show in the screenshot of the Rate Budget Panel .