dvb

Strange because Feflow doesn't stop in transient for convergence reason.

maybe you are looking at the time step instead of the real time ?

Thanks

One questions then:

We can logically reduce the fluctuations by constraining the time steps size. Is there a rule of thumb to say that a certain time step size is still ok in this method ? Not sure if I am clear ... e.g. the model starts to fluctuate when time steps reach sizes > 100 days. If I constrain the time steps to 50 days I reduce significantly the fluctuations. However I am not sure if this is a reasonable approach and if I can validate the model by doing so. After doing so I can run the model in SS, one or two times, after which the convergence is failing again.

In our case we effectively see that fluctuations are more important at pumping wells or along some specific recharge locations (e.g. foothills recharge). However a naked model (no internal bcs) still fluctuates (fluctuations are less important but still exists). We then believe that the geometry combined with the K distribution is the main reason for having such oscillations, but we have difficulties to see how to get rid of the problem (e.g the geometry and K are realistic, the border bcs are very simple constant heads).

Sometime you have a model that converges in SS, that has nice looking heads, but that is not that correct:
- If you run multiple times the exact same model, with different initial heads, you may find different results. In my case I found that the difference is rougly +/- 5 to 10 cm, depending on the nodes (with heads ranging over 30 m).
- In "steady transient" (steady bcs, transient run, high initial heads), heads converge globally toward some "making sense values" however they can fluctuate by an order of several meters, especially at wells but not only.

My model is a phreatic one. What are the rules of thumb to interpret this kind of results ?