Hi Ranjeet,
regarding the formulation: there are no publications using the
poromechanics module of Dumux 3, yet. But, you can have a look at the
PhD thesis of Martin Beck:
https://elib.uni-stuttgart.de/bitstream/11682/10435/3/Promo_MartinBeck.pdf
and in particular the sections 3.1.1 and 3.1.2. Equation 3.6 states the
momentum balance equation of the porous medium right before the
linearization. This is what is currently solved in Dumux. This implies
that you should have knowledge about your initial stress/deformation
conditions, or, solve for them primarily. In other words, if you
initialize your system with non-zero fluid pressures, you will observe
stresses/deformations caused by the initial conditions. If gravity is
neglected and incompressible fluids are considered, you could start your
simulation with zero pressure and zero displacement.
Regarding the deformation-dependent porosities: That depends on your
application. Currently, there is an issue with the coupling derivatives
of the storage term, and thus, if the porosity is chosen
deformation-dependent, the non-linear solver convergence deteriorates
significantly. On the other hand, deformation-dependent permeabilities
work fine.
We are planning to fix this issue very soon and hope that you want to
use Dumux for you application. We will not be able to fix it until the
3.2 release which is scheduled for a few weeks from now. If you want, I
can point you to a fix branch on which the bugfix is done in an
unsatisfactory way, but on that branch you could develop your
application for now. Once we have solved the problem you could switch
back to the release branch.
Regards,
Dennis
On 29.03.20 15:01, Ranjeet kumar wrote:
Hi All,
I want to develop a poroelastic model using el2p module in Dumux 3.1.
As per Dumux2.12 class documentation, soil mechanics sign convention
(i.e. compressive stresses are negative) has been used in el2p module.
However, papers & thesis based on Dumux2 has used opposite sign
convention. Can you clarify which sign convention is being used in
Dumux3.1?
Q2. As a linearised form of momentum balance equation is being solved
in el2p model, the solution effective stress obtained from:
const auto effSigma = StressType::effectiveStressTensor(*this,
element, fvGeometry, elemVolVars, fluxVarsCache);
is the total effective stress or change in effective stress with
respect to initial effective stress?
References:
1. p-3, Volume-Based Modelling of Fault Reactivation in Porous Media
Using a Visco-Elastic Proxy Model. Martin Beck1 · Gabriele Seitz1 ·
Holger Class1
2. p-3, Modelling fault reactivation with characteristic stress-drop
terms. Martin Beck and Holger Class
3. p68-69, Coupling Models of Different Complexity for the Simulation
of CO2 Storage in Deep Saline Aquifers
Thank you,
Regards,
Ranjeet
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