How to model a drainage

[tobret]

Hello dear helpers,

First of all I like to thank you for your support so far, it was very helpful.

I have a question about modelling a threshold of a door made out of steel (see the picture below).
Modelling this Detail without rain produces no error, but after adding rain the calculation ends after one month (starting at the first of October). I think happens because the concrete marked in the picture below (red square) gets saturated with water. I find this quite confusing, because I thought that the gravel should let the water of the rain flow into the sand below. Is it possible to Change the material proberties of the gravel to "make" the rain flow more vertiacally than horizontally?
What other possibilities do I have in modelling a Drainage?
As gravel I used "generischen Kies" des Fraunhofer IPB and as sand I used "sand" out of the "Nordamerikanischen Datenbank".
As outside surface conditions I used the weather file Holzkirchen, set R1=1 and R2=0 and set he adhering fraction of rain to 0.5 (I think 1 should be the right value here, because the whole rain will be absorbed of the surface).

Thanks for your help.

Tobias

[Christian Bludau]

Dear Tobias,

the calculation broke probably because you supersaturated the material using a tom high amount of rain. As in WUFI Pro there is the possibility to cut-off rainwater and sources, WUFI 2D does not have this function yet and will end in convergence problems.
Further, WUFI is not able to take in account seepage water. So no water will flew from your gravel into the sand.
Wufi can only take in account capillary effects, you can steer by adapting the transport coefficients for suction and redistribution (normally there should not be capillary transport in gravel). If you like to bring some water into your sand, you also can try to do it by using a moisture source there (maybe as a percentage of rain) - but that also may cause calculation problems by too high saturation.

Christian