Dear Sebastian,
you can't use everywhere Neumann when solving an incompressible 1p
problem, because then
your pressure solution is only defined up to some constant.
Why didn't you set everywhere Dirichlet according to your initial
conditions?
Best regards,
Martin
On 14.09.21 09:32, Alexander Sebastian Hogeweg wrote:
Dear Martin,
Attached you can find the corresponding files. Additionally, I forgot
to tell you that I am now using Neumann no-flow boundaries at all
boundaries.
Thank you in advance and if you need further data, just let me know.
Best Regards
Sebastian
*Von:*Martin Schneider <[email protected]>
*Gesendet:* Dienstag, 14. September 2021 09:15
*An:* Alexander Sebastian Hogeweg
<[email protected]>;
[email protected]
*Betreff:* Re: AW: AW: [DuMux] Heterogeneous cornerpoint grid -
Pressure drop/increase in scattered cells
Dear Sebastian,
could you please also provide the header files of your test case.
It would help to see the boundary conditions, etc.
Best regards,
Martin
On 14.09.21 08:36, Alexander Sebastian Hogeweg wrote:
Dear Martin,
First of all, thank you again for your time. Now, I built a 1p
(liquid) cornerpoint model to find the origin of the problem.
However, now I am observing a pressure change in the complete
structure. The attached images represent the pressure initially
and after the first timestep (100s). The initialization is done
using the hydrostatic pressure (simpleH2O):
values[0] = globalPos[2] * 1000 * gravity()[2];
The petrophysical properties are defined as homogeneous (k=1mD,
phi = 0.2). The structure's thickness is approximately 190m which
should induce a pressure difference of ca. 19 bar along with the
structure. After the first time step, the pressure difference
increases to 66bar, which I do not understand. Do you have any
ideas about what is causing this problem?
Thank you in advance.
Best regards,
Sebastian
*Von:*Martin Schneider <[email protected]>
<mailto:[email protected]>
*Gesendet:* Freitag, 3. September 2021 11:43
*An:* Alexander Sebastian Hogeweg
<[email protected]>
<mailto:[email protected]>;
[email protected]
<mailto:[email protected]>
*Betreff:* Re: AW: [DuMux] Heterogeneous cornerpoint grid -
Pressure drop/increase in scattered cells
Dear Sebastian,
I just checked the tpfa darcylaw:
https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/flux/cctpfa/darcyslaw.hh
<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
<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]>
<mailto:[email protected]>
*Gesendet:* Freitag, 3. September 2021 09:37
*An:* DuMux User Mailing List
<[email protected]>
<mailto:[email protected]>; Alexander Sebastian
Hogeweg <[email protected]>
<mailto:[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
_______________________________________________
DuMux mailing list
[email protected]
<mailto:[email protected]>
https://listserv.uni-stuttgart.de/mailman/listinfo/dumux
<https://listserv.uni-stuttgart.de/mailman/listinfo/dumux>
_______________________________________________
DuMux mailing list
[email protected]
https://listserv.uni-stuttgart.de/mailman/listinfo/dumux
