Hi Lorenzo,
you can have a look at the regularized material laws to see how the dumux splines can be used. It's a third order polynomial spline. For example, in check out the pc() function in dumux/material/fluidmatrixinteractions/regularizedvangenuchten.hh The spline there is constructed such that it is a continuous and differentiable continuation of the capillary pressure-saturation relationship above a given treshold. As input you give it two pairs of x/f(x) values as well as the desired slopes at these points. But there is other constructors available in case that suits your data better. You can have a look at this in dumux/common/spline.hh Cheers, Dennis ________________________________ Von: Dumux <[email protected]> im Auftrag von lc <[email protected]> Gesendet: Montag, 3. Dezember 2018 15:42:01 An: [email protected] Betreff: [DuMuX] about spline Hello, I have just implemented a simple spline to interpolate raw data of capillarity and permeability but I found that there is already such a function in Dumux. Which type of spline is implemented? Something like cubic monotonicity preserving? How can I use it? For example, would be convenient to call it from the material laws definition in /dumux/material/fluidmatrixinteractions/2p Is there any example? Kind regards, Lorenzo On 03.12.2018 15:41, Gläser, Dennis Hi Lorenzo,DUMUX/dumux/dumux/material/fluidmatrixinteractions/2p regarding your point (3): Let us consider the mass balance equation for one of the phases. Then, for outflow BCs the flux across the boundary is computed by using the current pressure gradients. For a darcy flux this would mean -(K*gradP)*normal is evaluated on the boundary. Afterwards, the flux is turned into a mass flux by multiplying with the mobility and the density, for which we typically use a simple upwind scheme. Thus, these values are obtained from inside the domain, which means that this only works well as long as you really have a flux leaving the domain. If the sign flips (essentially an inflow boundary), mobility and density are not defined. With respect to your question what the difference is: you could achieve the same thing manually by implementing the above mentioned stuff into the neumann() function: But note that especially for cell-centered schemes the outflow BCs are rather tricky to realize and personally I would try to avoid them and restrict myself to Neumann and/or Dirichlet BCs where you actually know what exactly happens. Best wishes, Dennis ________________________________ Von: Dumux <[email protected]><mailto:[email protected]> im Auftrag von lc <[email protected]><mailto:[email protected]> Gesendet: Montag, 3. Dezember 2018 12:37:19 An: [email protected]<mailto:[email protected]> Betreff: [DuMuX] on IMPES, grid adaptation and BCs Hello, I have the following questions: 1) Is it possible to run IMPES algorithm in sequential (not implicit) mode without considering capillarity forces (pressure)? 2) Is it possible to do some sort of grid adaptation, for example locally refine the (unstructrured) mesh where the water saturation front becomes steeper? If yes, how, is there any example? 3) What actually the Outflow BC does? What is the difference with Neumann? Thank you very much! Kind regards, Lorenzo _______________________________________________ Dumux mailing list [email protected]<mailto:[email protected]> https://listserv.uni-stuttgart.de/mailman/listinfo/dumux
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