> On 2. Jun 2020, at 14:15, kenza bouznari <[email protected]> wrote: > > Hello, > > I would like to understand how Dumux estimates the effective diffusion > coefficient Deff and the tortuosity of a soil?
Hi Kenza, it depends on what law you set as EffectiveDiffusivityModel property. For example the 2pnc model (https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/porousmediumflow/2pnc/model.hh <https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/porousmediumflow/2pnc/model.hh>) per default sets this to an implementation based on a paper by Millington & Quirk (https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/material/fluidmatrixinteractions/diffusivitymillingtonquirk.hh <https://git.iws.uni-stuttgart.de/dumux-repositories/dumux/-/blob/master/dumux/material/fluidmatrixinteractions/diffusivitymillingtonquirk.hh>). You can change that by implementing your own model and setting the property to your new class. > I also want to ask you what's the difference between a simplex type and a > cube type of a structured mesh? The difference (as you can see in your results where you show the grid) is that Alugrid’s cube type means quadrilateral elements in 2d and hexahedral elements in 3d, the simplex type means simplex elements (triangles, tetrahedrons). > because the choice of this option greatly influences the behavior of my > results. here is an example in the images below. Knowing that the only thing > that I changed is the type of the mesh (image 1: SET_TYPE_PROP > (HeterogeneousProblem, Grid, Dune :: ALUGrid <2, 2, Dune :: cube, Dune :: > nonconforming>); > (image 2: SET_TYPE_PROP (HeterogeneousProblem, Grid, Dune :: ALUGrid <2, 2, > Dune :: simplex, Dune :: nonconforming>) > P.S. It is an injection of gas into sand saturated with water. What discretisation scheme are you using? Which model? Timo -- _________________________________________________ Timo Koch phone: +49 711 685 64676 IWS, Universität Stuttgart fax: +49 711 685 60430 Pfaffenwaldring 61 email: [email protected] D-70569 Stuttgart url: www.iws.uni-stuttgart.de/en/lh2/ _________________________________________________ > <image.png> > > > <image.png> > Thank you for your time, > > Kenza > _______________________________________________ > Dumux mailing list > [email protected] > https://listserv.uni-stuttgart.de/mailman/listinfo/dumux
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