Hi Dmitry,

I will try to answer your questions below:

1.) In Dumux, we consider mass or mole fractions (depending on whether you set the Property "UseMoles" to true or false.
     These fractions are always with respect to a given phase.
      For example x^N2_gas would be the the mole fraction of the component "N2" within the "gas" phase.

      In what context did you encounter "concentration" in Dumux?

2.) This  depends on what you set for the Property "ReplaceComponentIndex". If you set that to a value > numComps,
      you consider one balance equation for each component separately.

      If, for instance, you have a H20-N2 Fluidsystem (2 components) und you set ReplaceComponentIndex = 0,       the balance equation of the 0th component (H20) will be replaced by a total mass/mole balance for the entire phase.       Depending on that is the Neumann flux. For ReplaceComponentIndex = 0, you will inject a certain total mass/mole flow       for eqIdx = 0, while for ReplaceComponentIndex  = 2 ( > numComps), you will inject a certain mass mole/flow for only the H20
     component.


Hope that helps!

Best wishes
Kilian

On 11.02.21 12:14, Dmitry Pavlov wrote:
Hello,

I ran into some strange issue in my porous flow simulation and I think it may come from my misunderstanding of DuMux subtleties of multi-component flow.

Could anybody please clarify things a bit for me?

1. What is a concentration -- is it the mass ratio of a component (e. g. polymer) in the whole wetting phase (solution), or mass ratio of the said component to the 0-th component (water)?

2. When I put neumann() conditions for injection or extraction fluxes, should I assume that the flux that corresponds to the main component is the molar flux of water, or the molar flux of phase (water + polymer + other components if any)? I see examples in dumux/test/porousmediumflow that seem to imply different answers to this question.


Best regards,

Dmitry

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Kilian Weishaupt
Institut für Wasser- und Umweltsystemmodellierung (IWS)
Lehrstuhl für Hydromechanik und Hydrosystemmodellierung
Universität Stuttgart, Pfaffenwaldring 61, 70569 Stuttgart
Email: [email protected]
Telefon: 0049 711 685-60461 ** fax: 0049-711-685-60430
http://www.hydrosys.uni-stuttgart.de
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