Posted Thu, 05 Jan 2017 22:08:07 GMT by tempest
Hello all!

I am working on a problem that would be great to be able to automate; I am running particle tracks for about a hundred different conductivity schemes. I have figured out how to call feflow from a command line and automate every other aspect of the process other than exporting the particle track data that is generated during each simulation. I've come to this forum seeking the sage one who might tell me if this functionality is even possible. Please let me know what you can!

Posted Fri, 06 Jan 2017 11:03:20 GMT by Björn Kaiser
An automation to generate particle tracks is not possible in FEFLOW. In contrast, workflows to post-process computational findings as derived by age-based computations can be automatized. 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 delineation of catchment zones can be automatized if you query the concentrations at the computational nodes.

Please let me know if you are further interested in automatizing workflows to post-process age-based computations. In this case I could provide required API functions.
Posted Fri, 06 Jan 2017 17:14:01 GMT by tempest
Wow! This is a very helpful response. It seems like it might take me some significant time to implement this, but I am interested. I will speak with my adviser to see if it is something that would be worth working through; if we are only doing one or two more sets of these particle tracks then I might as well do them by hand for all the time I will spend figuring out the coding for all that post-simulation (I am not a classically trained computer scientist, just an engineer sadly) I will certainly get back to you if we plan to automate using your post-process idea! Thanks a lot!
Posted Wed, 18 Jul 2018 19:44:20 GMT by S Heermann
Are diffusion/dispersion  reversible processes?
Posted Wed, 25 Jul 2018 12:46:32 GMT by Björn Kaiser
Diffusion is an irreversible process. Accordingly, in age-based backward simulations (Exit Probability, Life-Time-Expectancy) only the advective components of the advective-diffusive transport equation is reversed.

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