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Publications
Publications (7)
We investigate the fluid flow field in a fractured granite core sample. Sequential imaging with Positron-Emission-Tomography (PET) allows direct reconstruction of flow streamlines, thus providing a unique insight into the fluid dynamics of complex fractured crystalline materials. Pulse migration experiments using the positron-emitting radionuclide...
The modeling of fresh concrete flow is still very challenging. Nevertheless, it is of highest relevance to simulate these industrially important materials with sufficient accuracy. Often, fresh concrete is assumed to show a Bingham-behavior. In numerical simulations, regularization must be used to prevent singularities. Two different regularization...
Surface chemistry of mineral phases in aqueous environments generates the electrostatic forces involved in particle-particle interactions. However, few models directly take into account the influence of surface speciation and changes in solution speciation when the diffuse layer potential profiles of approaching particles overlap and affect each ot...
Reactive transport modeling contributes to understand geophysical and geochemical processes in subsurface environments. Operator splitting methods have been proposed as non-intrusive coupling techniques that optimize the use of existing chemistry and transport codes. In this spirit, we propose a coupler relying on external geochemical and transport...
Reactive transport modeling in porous media involves the simulation of several physico‑chemical processes: flow of fluid phases, transport of species, heat transport, chemical reactions between species in the same phase or in different phases. The resolution of the system of equations that describes the problem can be obtained by a fully coupled ap...
Questions
Questions (5)
The extended law of Darcy (without gravity term) will look like:
q1 = (kr1k/u)*grad(P1)
q2 = (kr2k/u)*grad(P2)
After discussing with a physician, he tells me that if we are considering the multiphase flow we should take into account the cross term, namely the influence of the gradient pressure of the phase 2 over the phase 1 and reciprocally. Therefore the equation for 1 (either for 2) should look like (more or less):
q1 = (kr1k/u)*grad(P1)+(kr12k/u)*grad(P2)
This term is usually not taken into account in the modelization of multiphase flow. I am wondering why? Do you know any article where it is taken into account in the Darcy scale?
Thanks
A part from comsol that can be called from MATLAB, java, etc.
Which other software exists?
Which other software do batch reactions (for geochemistry) with an equilibrium constant based method? Are they providing a COM interface like iPHREEQC?
I am coupling COMSOL with iPHREEQC in a 1D problem through MATLAB, but due to the obtained results I am not sure if what I am doing is correct. The process is as follows:
Set up:
In COMSOL I create an interval with the following boundaries conditions in the edges (upstream: constant concentration value, downstream: no flux). I use the "Solute Transport" equation of COMSOL. The velocity is 0 (Therefore there is not dispersion), the pore volume fraction is 1, all sorption parameters are 0, and the diffusion value is the same for all the transported species. The tortuosity factor is drawn from Millington and Quirk model, as the system is saturated and the porosity is one, the diffusion phase of liquid is equal to the effective diffusion.
At each node of the interval (Except for the edges where I have the boundary conditions), I run a Batch Reaction. These batch reactions are composed of a Solution Block and a Equilibrium_Phases Block. So, It will look like:
Solution
units mol/kgw
Si 2.223e-6
C 6.466e-6
pH 12.465 charge
Cl 7.27e-4
Ca 2.057e-2
Equilibrium_Phases
Calcite 0 130.68e-5
CSH1.6 0 10.87e-5
Portlandite 0 11.6e-5
SELECTED_OUTPUT
-high_precision true
-pH true
-totals Si C Ca Cl
-equilibrium_phases Calcite CSH1.6 Portlandite
Followed Process:
As I just have Diffusion and I trying to emulate PHREEQC reactive transport I do the following process: Chemical Process --> Transport (just Diffusion) --> Chemical Process (for each Operator Splitting time step). I am using a SNIA (sequential non-iterative approach).
So, I run my batch reactions, drawn the values from the selected output (look example of the set up) and modified the old values for the new. Then I do a Transport step for the mobile species (Solution), replace my old values for the new ones and run a new batch reaction.
Problem:
I have noticed that every time that I decreases the operator splitting time step the amount of mineral that I precipitated or dissolved varies, even though the concentration values are equal. What can be the cause of such problem?
