Dear Nicolas,
yes, I can observe lower saturations at the injection points now.
As Timo explained the injection of pure CO2 can lead to a phase change,
reducing the liquid saturation and allowing the brine component to be
transported in the mobile gas phase. When the saturation drops to 0 the
model performs a switch of primary variables to allow the simulation to
continue.
Best regards,
Mathis
On 31/08/2023 12:31, Nicolas Pillardou wrote:
Dear Mathis,
Thank you for your answer.
You are right, I omitted some information, sorry. I am working with version 3.4
with my personal test case, but the decrease under the S_wr is noticeable also
in the master branch on the test CO2.
You also have to modify the final time to:
TEnd = 1e7 # [s]
I have just tested with the box discretization method and it seems to drop
below the S_wr just after 2.4e6 s. I have attached pictures to illustrate this
phenomenon.
Do you observe something similar with this configuration?
Thank you again
Best regards,
Nicolas Pillardou
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De: [email protected]
À: "dumux" <[email protected]>
Envoyé: Jeudi 31 Août 2023 12:00:02
Objet: DuMux Digest, Vol 149, Issue 6
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Today's Topics:
1. Questions about residual saturation (Nicolas Pillardou)
2. Re: Questions about residual saturation (Mathis Kelm)
----------------------------------------------------------------------
Message: 1
Date: Thu, 31 Aug 2023 09:17:47 +0200 (CEST)
From: Nicolas Pillardou <[email protected]>
To: dumux <[email protected]>
Subject: [DuMux] Questions about residual saturation
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="utf-8"
Dear Dumux Community,
I'd like to ask you a quick question about residual saturation, which may seem
trivial to you.
In one of my simulations that considers two-phase flow (CO2 model), I set:
Swr = 0.3
Snr = 0.05
When I look at the liquid saturation solution obtained, it is given between 0 <=
S_w <= 1. Why the minimum value reached by this liquid saturation is 0 ? Shouldn't
it be Sw = 0.3 instead with the residual liquid saturation ?
Is the output saturation represented by the effective saturation instead of the
real liquid saturation ?
I tested the same parameters in the co2 model provided in the Dumux tests and
it appears to be the same behaviour. The saturation exceeds the residual
saturation.
I also noticed that this minimum saturation value is different for several mesh
sizes. Does this seem consistent to you?
Thank you in advance for your answers.
Best regards,
Nicolas Pillardou
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Message: 2
Date: Thu, 31 Aug 2023 10:42:07 +0200
From: Mathis Kelm <[email protected]>
To: [email protected]
Subject: Re: [DuMux] Questions about residual saturation
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
Dear Nicolas,
the volume variables and output should be the real saturations, only
when evaluating the material laws do we use them to compute effective
saturation. Depending on the problem you can have values outside the
range between residual values, e.g. with fully saturated initial conditions.
I was unable to reproduce your error, which version of DuMux are you
using and which of the tests were you using? Testing both the master
branch and release 3.7, if I change the values for in
`test/porousmediumflow/co2/params.input` and run test_co2_box then the
liquid saturation stays between 0.43 and 1.0. So it exceeds Sw = 1.0 -
Snr but doesn't drop below Swr.
If you haven't reached mesh convergence then the solution can depend on
the discretization length. If I'm discretizing a linear solution the
minimum value with naturally decrease with increased resolution. With
refinement your solution and thus the minimum value should converge.
Without further information it's difficult to say if there is some issue.
Best regards,
Mathis
On 31/08/2023 09:17, Nicolas Pillardou wrote:
Dear Dumux Community,
I'd like to ask you a quick question about residual saturation, which
may seem trivial to you.
In one of my simulations that considers two-phase flow (CO2 model), I set:
Swr = 0.3
Snr = 0.05
When I look at the liquid saturation solution obtained, it is given
between 0 <= S_w <= 1. Why the minimum value reached by this liquid
saturation is 0 ? Shouldn't it be Sw = 0.3 instead with the residual
liquid saturation ?
Is the output saturation represented by the effective saturation
instead of the real liquid saturation ?
I tested the same parameters in the co2 model provided in the Dumux
tests and it appears to be the same behaviour. The saturation exceeds
the residual saturation.
I also noticed that this minimum saturation value is different for
several mesh sizes.?Does this seem consistent to you?
Thank you in advance for your answers.
Best regards,
Nicolas Pillardou
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--
********************************************************
Mathis Kelm
Universitaet Stuttgart
Institut fuer Wasser- und Umweltsystemmodellierung
Lehrstuhl fuer Hydromechanik und Hydrosystemmodellierung
Pfaffenwaldring 61, 70569 Stuttgart
Tel.: 0711/685-60146
[email protected]
https://www.iws.uni-stuttgart.de/lh2/
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