Dear Lorenzo,
generally for cell-centered discretizations in Dumux, Dirichlet boundary
conditions are weakly enforced on the boundary. Your first degree of
freedom is half a cell away from the boundary, so it doesn't necessarily
have to be the same as the Dirichlet value.
In order to see if this is actually a mistake or not, we would need at
least a picture of the saturation and pressure fields. If you have some
gradients and varying saturation close to the boundary it's perfectly
normal that the cell values are different than the boundary values.
For example, does you flow field have finger effects close to the
boundary? That would explain why the profile in the first cell looks
like it does.
Best wishes
Timo
On 27.03.19 14:24, lc wrote:
Hello Dumux team,
We are, finally, in the post-processing phase, aiming at publishing
soon ... but we observed a scaring issue concerning the verification
of the BC at the inlet.
I'm using Dumux 2.12 with the 2p sequential model for a rectangular
domain discretized with a cartesian structured grid with water inflow
(q_w = 0.0001446759 kg / m^2 - s). At the inlet I also impose a
Dirichlet condition on water saturation, s_w = 0.7856 (smax).
The observed issue is visible in the png file
(boundary_condition_t=500_kern1.png):
the horizontal axis in the figure corresponds to the y axis of the
simulation domain (m) and the vertical axis in figure reports the
saturation levels, (s_w).
We see at t = 500 days from the start of the simulation which runs
until 688 days.
So, as we can see, the Dirichlet BC at inlet, s_w = 0.7856 is not
verified. At t = 0, it is ok, but at every later step not any more,
getting a bigger and bigger discrepancy.
May you help me to shed some light on this, please?
I enclose all necessary files to reproduce such behaviour, in case you
have the possiblity to do it.
Kind regards,
Lorenzo
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Timo Koch phone: +49 711 685 64676
IWS, Universität Stuttgart fax: +49 711 685 60430
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D-70569 Stuttgart url: www.hydrosys.uni-stuttgart.de
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