Large continuity error

Hi OGS-Users,

I'm simulating a section of river sediment modeled by a structured mesh
with a sinusoidal pressure boundary on top and a source term at the
bottom. When I calculate the interfacial flux over an arbitrary
horizontal cross section, I expect it to be equal to the source term at
the bottom (3.667e-6). What I actually get for the 25 layers of my
structured mesh is:
layer flux through layer
24 0.0107254663517 (pressure boundary)
23 0.000146936095482
22 7.15915546532e-05
21 4.38169573139e-05
20 2.43636480998e-05
19 6.28636072463e-06
18 3.4735641863e-06
17 3.64290608001e-06
2-16 ~3.667e-6
1 3.66709237359e-06
0 0.0176977869523 (source term = 3.667e-6)

i.e. the uppermost layer (neglecting the boundary layer itself) has a
continuity error of 40 * expected flux. Unfortunately, this layer is the
most interesting to me. Do you know a way to reduce this error?

Find the case attached. Sorry for 5MB attachment, but well, 21st century...

I calculated the interfacial flux via python
("") but similar effects can be seen using

Any ideas?

Best regards

Gerrit (4.9 MB)


Gerrit Laube
Department Hydrogeologie
Department Hydrogeology
Helmholtz-Zentrum für Umweltforschung GmbH - UFZ
Helmholtz Centre for Environmental Research GmbH - UFZ
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