Dear Sebastian,
I just checked the tpfa darcylaw:
https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/flux/cctpfa/darcyslaw.hh
and it seems that you can't use my previous suggestion and simply use
absolute values in the functions of
https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/discretization/cellcentered/tpfa/computetransmissibility.hh
<https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/discretization/cellcentered/tpfa/computetransmissibility.hh>
because there in the darcylaw we calculate the transbissibility t_j
related to the neighboring element as:
|-1.0*computeTpfaTransmissibility(....)
Did you try to change
||https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/flux/cctpfa/darcyslaw.hh
such that all transmissibilities for the flux calculation are positive.
|
Maybe you could also start setting up a 1p problem and try if it works
there.
Best regards,
Martin
On 03.09.21 11:11, Alexander Sebastian Hogeweg wrote:
Dear Martin,
thank you for the fast response. I followed your recommendations and
changed the cell center location based on the arithmetic mean
(|HACK_CELL_CENTROIDS)|. Here, I am still facing negative values for
the grid block transmissibilities (ti).
Additionally, I use the absolute value for the transmissibilities
leading to positive values. However, the pressure drop/increase in
some cells is still observable.
Do you have other ideas, which could cause this behavior? Thank you in
advance.
Best regards,
Sebastian
*Von:*Martin Schneider <[email protected]>
*Gesendet:* Freitag, 3. September 2021 09:37
*An:* DuMux User Mailing List <[email protected]>;
Alexander Sebastian Hogeweg <[email protected]>
*Betreff:* Re: [DuMux] Heterogeneous cornerpoint grid - Pressure
drop/increase in scattered cells
Dear Sebastian,
for CP-grids it might happen that the centroid is located out of the
cell such that the currently implemented
transmissibility calculation yields negative values.
Did you check if all the transmissibility calculated with the
functions in the following header
https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/discretization/cellcentered/tpfa/computetransmissibility.hh
<https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/discretization/cellcentered/tpfa/computetransmissibility.hh>
are positive?
I guess you will observe negative values. There are two solutions to
overcome this
1. Try to use another cell center instead of the centroid.
2. Try to use the absolute value of the transmissibility (corresponds
to switching the normal vector of the corresponding face)
I hope this solves your problem.
Best regards,
Martin
On 02.09.21 18:15, Alexander Sebastian Hogeweg wrote:
Hello everyone,
I am facing a problem during the simulation of an underground gas
storage scenario. The used grid is a cornerpoint-grid with a
heterogeneous distribution of permeability and porosity.
Additionally, the structure contains a fault connecting a lower
part of the formation. The used fluid model is 2pnc (h2on2o2), and
the initialization is based on the example 2p_cornerpoint
(hydrostatic pressure and pores fully water-saturated). At the top
and bottom of the structure, Neumann (no-flow) boundaries are
defined (Dirichlet at the sides with initial). In the present
status, the molecular diffusion is deactivated, and additionally,
the centroid cell center location is used.
After the initialization (looks all right), the pressure in some
cells of the lower part increases while neighboring grid blocks
show a lower pressure. Attached you can find some images showing
the problem (Image 1 and 3: t=0; Image 2 and 4: t =6000s (timestep
8) and the problem file. Other (more conforming)
cornerpoint-grids do not show this behavior.
Overall, I would like to know if somebody else observed a similar
situation and could help me with the problem.
I appreciate any help you can provide, and please let me know if
you need further information.
Best Regards,
Sebastian
Dumux Version: 3.4
Model: 2pnc
Grid type: Cornerpoint
Fluid system: h2on2o2.hh
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