Particle Tracking

Hi there,

Happy to see that this forum is up again and hope you could help me with a question about particle tracking

I have a transient flow model (phreatic mode, 13 layers) where I simulated forward pathlines travelled by particles placed in the same location at different depths (from slice 1 to 8 ), but I noticed that FEFLOW produces pathlines also for particles placed in nodes whose elevation is constantly above groundwater elevation. How is that possible?

Thanks in advance,
Matteo

The handling of nodes above the gw surface depends on the mode you're using for those: 'confined', 'free', 'phreatic', 'unsaturated'. Except for 'free', FEFLOW will calculate also hydraulic head above the GW level, and particles will thus follow the head gradient also at nodes above the surface. You should check what option you are using and what this option means for the handling of the unsaturated zone.

Hi Peter,

Thank you very much for your quick reply.

The model runs in phreatic mode and I am interested in understand the fate of these particles. Do pathlines resulting from particles placed in unsaturated slices make hydrogeological sense? Should I placed particles only in slices that I am sure are saturated throughout the run?

Thanks,
Matteo

I'd recommend to place the starting points in saturated locations only. Due to the simplification for the unsat zone that comes with 'phreatic' mode, it may happen that your particles travel through the unsat zone, though.