Dear Lorenzo,

There is a list of run-time parameters on the Dumux website, e.g. for the 2.12 release: https://dumux.org/doxygen/2.12/a06491.HTML


All run-time parameters are explained there. Does that help you? Additionally, it is always a good idea to have a look at the code to understand what it does. Simply grep for something that you are wondering about, e.g. by typing when you are in the dumux-module folder


grep -r "EnableInitializationIndicator"


The console will print parts of the code, which may be enough to get some understanding, and additionally you can open the files and read through the code.


I do not understand your question about the alugrid.cfg file... I never did anything in particular with it.


Best regards,

Beatrix



Am 05.12.18 um 10:56 vorm. schrieb lc:

Hello,


thanks for the previous answer, it was helpful.


About grid adaptation, I tried but I get strange refinement, as reported in the figure.


In particular, I don't know how to set this block:


[GridAdapt]
EnableInitializationIndicator = 1
RefineAtDirichletBC = 1
RefineAtFluxBC = 2
MinLevel = 0
MaxLevel = 2
RefineTolerance = 0.05
CoarsenTolerance = 0.001


Also, should I use the alugrid.cfg file? At the moment I don't use.

May you give me some hints please?


Kind regards,

Lorenzo


On 03.12.2018 15:41, Gläser, Dennis wrote:

Hi Lorenzo,


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]> im Auftrag von lc <[email protected]>
*Gesendet:* Montag, 3. Dezember 2018 12:37:19
*An:* [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

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--
*******************************************************

Beatrix Becker

Department of Hydromechanics and Modelling of Hydrosystems (LH2)
Institute for Modelling Hydraulic and Environmental Systems (IWS), University 
of Stuttgart
www.hydrosys.uni-stuttgart.de
email: [email protected]
Pfaffenwaldring 61
70569 Stuttgart
Tel.: ++49  711 / 685-60500

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